EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: Liv on March 04, 2015, 08:38:12 am
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Features:
• output voltage: 0…36 V
• output current: 0…4 A
• voltage resolution: 10 mV
• current resolution: 1 mA
• operation modes: CV, CC
• down programmer circuit
• remote voltage sense amplifier
• pure linear design
• multilevel output stage supply
• synchronous rectifiers
• digital calibration
• interface: USB (optocoupled)
• case type: Z-2A (Kradex, Poland)
To minimize dissipation power output stage uses 4-level supply. It provides high dynamics, while conventional circuits with transformer tap switching or preregulator need time for bulk capacitors charging. This power supply also uses MOSFET synchronous rectifiers. Fast discharging of load capacitance provided using down programmer circuit. High dynamics and very small output capacitor prevents current spikes at CV-CC transition. Power supply circuit ready for remote voltage sensing. Control system based on ARM-microcontroller STM32F100C8T6B. User control elements – incremental encoder and 4 pushbuttons. Settings -via local menu or via USB interface.
1-ampere and 2-ampere versions here: PSL-2401/2 (https://www.eevblog.com/forum/projects/diy-bench-power-supply-psl-24012/)
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PCB project for manufacturing:
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Nice try!
Good to see you here :)
I've made several devices by your design and I'm completely happy with them (though minimalistic amount of controls was discussed elsewhere :)
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I seems to be a nice unit. Is there a place fore someone to buy it?
Alexander.
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Nice project! Clean mechanical build, too.
The toroid is custom manufactured I guess?
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that looks pretty sweet mate.
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Thanks Liv for sharing all details with us. Schematics looks awesome, I have some questions if you're are willing to address it. Some details is far beyond my comprehension.
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Nice try!
(though minimalistic amount of controls was discussed elsewhere :)
Thank you!
Minimalistic control - this is real drawback. Mainly concerns of my sinal generators projects. The power supply has enough balanced controls: separated buttons for V, I settings, and encoder with adaptive speed and "Fine" mode allows edit setpoint quickly.
Is there a place fore someone to buy it?
I don't know. Project is open, somebody probable produce it.
The toroid is custom manufactured I guess?
Toroid based on 105W transformer for halogen lamps. Secondary winding (12V) was removed and replaced by 4 windings 2 x 8.5V and 2 x 10V.
Schematics looks awesome, I have some questions if you're are willing to address it. Some details is far beyond my comprehension.
Schematic has been designed to meet the high dynamics and precision (if you apply more precision opams and resistors with low TC). Very low output capacitance provides very low current spikes. I can set 36V, 0.005A and connect LED to the output. There in no even visible light flash, of course, no damage of LED. ADC uses oversampling to increase resolution. DAC uses addition sigma-delta part using DMA to increase resolution to 16 bits. For example, Agilent U8002 uses 12 bit DAC, voltage steps is not equal. This power supply does not have such a drawback because of increased DAC resolution. Any questions can be sent to e-mail wubblick@yahoo.com, just hard for me to speak in english.
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That is a pretty amazing power supply, congratulations! Could you tell me how you made the front panel?
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That is a pretty amazing power supply, congratulations! Could you tell me how you made the front panel?
Take a printer, print on paper (I use "silvery" looking paper), laminate. "Cold laminate" film seems to be the best option.
Use double-sided scotch tape to glue it.
As for the palstic carving - alsk LiV
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I used the blank panel of Z-2A case, that represents the polystyrene panel thickness of about 3 mm. Holes done using desktop milling machine, although it can be done using a drill and needle files. For display window I used a dark plexiglass. The sticker is printed on the film Oracal, cut on the plotter and laminated in the firm, engaged in advertising.
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Thanks. Very nice finish.
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Cool ! Thanks for sharing.
Really appreciate if you can share few captured scope's shots at it's dynamic performances like :
- Load transient response and recovery
- Over load/short circuit performance and it's recovery
- Over/under-shoot at CV->CC transition and vice versa.
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I have only analog scope, it's hard to make screenshot. I have about 150$/month, I can't buy digital oscilloscope. But I observe good compliance between Spice model and reality. Spice diagrams show the following: 1 - step from 2A to 4 A and back (C_load =100 uF); 2 - short circuit (0.01 Ohm, C_load =1 uF); 3 - CV->CC transition and vice versa (I = 3A, R_load transition 18 Ohm->6Ohm, C_load =1 uF).
For example (last image), in debug process (tuning frequency correction for CC-CC step) I compare real scope image with Spice diagram and found good compliance.
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Lovely work.
One question - you use a discrete synchronous FET bridge rectifier - did you consider using one of the monolithic ideal diode bridge controllers like the LT4320(-1) ? - cuts out a load of components and real-estate, plus its cheap, good to 72V and inputs from DC-600Hz.
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I know about LT4320, but it's two different universes - price LM393 and price LT4320. My version of synchronous rectifier is very inexpensive.
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I have only analog scope, it's hard to make screenshot. I have about 150$/month, I can't buy digital oscilloscope. .... <snip>
Ah .. don't worry, just build the circuit below and it should be cheap & easy, especially with your building skill there :-+.
Designed by one of the well respected member here, and this circuit should be handy to verify DC power supply whether it has a decent "dynamic performance" or not.
Click here -> Dynamic Electronic Load Project by Jay_Diddy_B (https://www.eevblog.com/forum/projects/dynamic-electronic-load-project/)
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I know about LT4320, but it's two different universes - price LM393 and price LT4320. My version of synchronous rectifier is very inexpensive.
LT4320 is about USD 4 here - you save a whole bunch of components by using something like that, plus a load of board real-estate (under the FETs) - I can't believe that its more expensive to use the 4320 than the discrete solution... over twenty components replaced by each single driver.
Not in anyway a criticism of your design, just you use other integrated solutions in the design, not least the uP... just seems a bit odd...
Cheers
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I can't believe that its more expensive to use the 4320 than the discrete solution... over twenty components replaced by each single driver.
You should believe it, at certain part of the world, for example mine :'(, say on a few bucks purchase on few chips, the shipping & handling charge sometimes can be as high as $70 to $100 like from well known Digikey/Mouser etc, or purchase it directly at the manufacturer e-shop like Linear Technology which sometimes even worst. |O
Oh yeah, we're not discussing about the local custom import tax yet and bla..bla... :palm:
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just build the circuit below
I'm just designs electronic load (see attachment), a project to link too primitive.
LT4320 is about USD 4 here
Very expensive. But you can not do without a microcontroller. We have completely different conditions in terms of money.
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The unit looks very professional and clean.
My $400 Agilent power supply will let the smoke out of an LED if connected at 36 volts and set to .005A!
I would like to hear more about how you used the Oracal film - did you get a small piece and use and inkjet printer - how did you do the front panel?
Good Work.
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how did you do the front panel
First, make all the necessary holes in the blank panel. Then the glass is made from smoked acrylic. You can use a transparent acrylic and film for window tinting for cars. Then stick label. Label ordered the firm engaged in advertising. They are printed on the Oracal film, laminated and cut on the plotter. One label is worth about $ 0.2. Install a circuit board through the glued plastic spacers - panel ready.
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Do you happen to have a bill of materials for the components (specially the mechanical things like that heatsink)? I'm interested in this, looks very nice. I have been looking to build a power supply for years, but I am never satisfied with the projects out there, many times they are too simple, others are too much hassle for the outcome and the rest never have what I need but yours seems to be so professional that I might put the effort into it. Also, it would be great to share the Gerber files, since the design is open :-+
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Do you happen to have a bill of materials for the components (specially the mechanical things like that heatsink)? I'm interested in this, looks very nice. I have been looking to build a power supply for years, but I am never satisfied with the projects out there, many times they are too simple, others are too much hassle for the outcome and the rest never have what I need but yours seems to be so professional that I might put the effort into it. Also, it would be great to share the Gerber files, since the design is open :-+
+1 on the BOM, I've already managed to convert the files to gerber :D I also agree, this looks like a great addition to the lab.
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Do you happen to have a bill of materials for the components (specially the mechanical things like that heatsink)?
Mechanical things are custom. For heatsink I used aluminum profiles with the treatment on the milling machine.
Attach several documents and control software.
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There are manual, but to translate it into English - very hard work for me. So I just translated table of contents. Interesting paragraphs from the Adobe PDF Reader can be copied and pasted into the Google Translate.
Attach a two-volume archive, as the size of the document 1.4 MB.
First, extract PSL-3604_v2e.z01 from PSL-3604_v2e_z01.zip and unzip PSL-3604_v2e.zip.
(ext .z01 not allowed this forum)
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Hi,
Any progress with your electronic load project LD-8020 ?
Looks very interesting and impressive !
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Progress is weak, with little free time. But gradually do.
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Very nice and professional project Liv.
Do you consider the data here as final ? Are there some bugfixes ?
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This is the final version. Circuits and boards have version 3 with all patches. Perhaps in the future there will be a new firmware with some additions. Current firmware version - 2.02.
Firmware update: version 2.03.
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Hi LiV,
So after one year later is there any progress with your very promissing LD-8020 electronic load project ?
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Currently, only the layout of front panel board is ready.
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Great! This is a step forward ! :-+
Any progress in power stage ? Can you give us some informations about your experiments ? (Stability, thermal behavior etc.)
Maybe some detailed schematics ?
I 'm working in a similar project this time, and any collected experience from others will be useful and appreciated !
Thanks.
Simon.
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The power stage in the design phase. I am now researching the scheme of Agilent N3304A.
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Thanks for your quick response
Excellent work. Very professional !!!!!
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Hi liv,
really great work:) it is a very nice power supply.
I had only one short question, over sw settings I saw it is possible to switch off the down programmer.
How did you realize that ? Cause I see no switched signal in the down programmer.
Thanks
Sven
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Thank you! When the output is enabled, the DP is always active. When the output is off, the DP can be enabled (DAC = 0, ON = 1) or disabled (DAC = 0, ON = 0). Of course, it would be better to have a separate DP control, but here it is not provided.
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Hi liv,
i have a sho question to your current limiter which is implemented with the components around vt9.
Will that work ? I ask me the question by myself cause over the current sensing resistors r27,r28,r25 and r26 it will not reach the 0,7 volts base emitter voltage at for example max 6 amperes or do I'm going wrong ?i try now to solve that via adding a additional 15k resistor between collector and base. That should work than.
Cheers
Sven
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Current protection on VT9 used in special cases and in normal operation the PSU never works. For example, it protects the output stage in case of short circuit the OUT+ terminal to the GND (not OUT-) when adjusting or repairing the device. Protection threshold set by a BE voltage (about 0.7V) and R25-R28 resistors values. This threshold should be higher than the guaranteed maximum PSU output current.
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Hi liv,
thanks for the answer. I see now a little bit clearer.
I have now build one prototype with a similar analog stage as yours. Only that I use
one voltage which comes from a switching power supply and is pre regulated 1,2 volts higher than the output voltage.
The control stage with current mirrors and op amps is the same as yours only I use max 44246 as op amp and op27g for voltage and current amplifiers.
I have the problem that I cannot go to 0 volts. My design goal is to adjust voltage in 1mv steps.
I don't know if that will work with the design.
I can only reach 0,3 - 0,4 volts as a minimum.
What I have not implemented is the higher ground which you have realize with op amp (com).
Could that be the problem?
Thanks sven
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I have now build one prototype with a similar analog stage as yours. Only that I use one voltage which comes from a switching power supply and is pre regulated 1,2 volts higher than the output voltage.
Using a switching preregulator has two drawbacks: a high level of high-frequency noise and poor PSU dynamic when adjusted upwards due to the need to charge the capacitor at the regulator output.
I have the problem that I cannot go to 0 volts. My design goal is to adjust voltage in 1mv steps.
If you do a precision power supply, it must be purely linear. Or use low-noise preregulator working at mains frequency. An example of such amateur PSU with 1 mV step here (http://koyodza.com/PSA2/index.php?lng=EN).
I don't know if that will work with the design.
I can only reach 0,3 - 0,4 volts as a minimum.
The PSL-3604 does not have such problems. There are two conditions to ensure zero output voltage: opamps supply voltage must be bipolar and unipolar DAC and ADC scale should be shifted up to a few hundred millivolts.
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Hi liv,
thanks for your quick reply.
I use for all op amps +- 15 volts.
I try to find out what the problem is.
Cheers
Sven
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The control voltage to set the voltage and current to be formed with respect to a level of 100 - 300 mV. The PSL-3604 is a signal COM, which is obtained from the reference voltage using resistor divider. Because unipolar DAC can not provide output voltage near zero.
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Hi liv,
for testing I use at the moment a analog pot which is connected between ground and 5volts.
I not test it with the Dac at the moment.
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How close to zero are you now when connect control input to the ground?
EDIT: sorry didn't see some of your previous post. Anyway I go down to zero even without using Liv's trick with shifting COM level to few hundreds mV.
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for testing I use at the moment a analog pot which is connected between ground and 5volts.
I not test it with the Dac at the moment.
Opams have a offset voltage. Therefore, accurate PSU output voltage can be achieved only after digital calibration. To compensate for both negative and positive offset with unipolar DAC, control signals must be level shifted by few hundred millivolts. Pots similar unipolar DAC, they can not provide the control voltage below zero.
Anyway I go down to zero even without using Liv's trick with shifting COM level to few hundreds mV.
This is not my trick, a similar solution is used, for example, Agilent U8002. If the offset is not done, the digital calibration of the zero point is impossible. The error at zero is dependent on the accuracy of the used opamps.
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Did anyone make BOM for this bench psu. I opened attachments in posts but i couldnt find it?
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Bom:
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Hi Liv
Thanks for posting this - it looks like a good design and I want to try out a modified design. I really like the output stage design; I think the the automatic range switching and missing auxiliary supply protection (using U3) are very nice. So much better than a tap changing relay!
There are some aspects of the design of the Power Supply Board that I would like to know more about.
- In the regulator control board, VT9 and VT10 obviously pull current out of the driver stage to adjust the output voltage. I can see why they are used in this way, but can you explain why their bases are connected to the voltage divider (R73+R74) / R77? What advantage does this offer compared to connecting to ground?
- What protection does the Remote Sense Protection circuit (VT11, VT12, VT13 etc.) offer?
- What do C28, C29, R42 and R54 do? Are they for damping of output voltage transients?
- What do C51 and R98 do? Are they for damping of CC to CV transition?
Cheers
jbb
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So much better than a tap changing relay!
Multi-level output stage provides a good dynamics in the full output voltage range. Using relay takes time to switch on the relay and charging filter capacitance. When the complexity of the load when the PSU must sharply raise the voltage during CV-CC transition, power failures are possible. For external programming via USB, this PSU is able to change the voltage up quickly, which may be important in automatic measurements. PSU with switching preregulator has similar drawbacks as the PSU with the relay. Additionally added interference. At the same time, the PSU with multilevel output stage also has disadvantages: the increased complexity, the relatively low efficiency. This solution is good if, when you need a low-noise power supply with good dynamics and average efficiency.
In the regulator control board, VT9 and VT10 obviously pull current out of the driver stage to adjust the output voltage. I can see why they are used in this way, but can you explain why their bases are connected to the voltage divider (R73+R74) / R77? What advantage does this offer compared to connecting to ground?
This divider forms a local negative feedback. It is good for the dynamics and stability of power supply.
What protection does the Remote Sense Protection circuit (VT11, VT12, VT13 etc.) offer?
This scheme is similar to the Agilent 6622. This limits the output voltage if the SENSE inputs are very different from the output.
What do C28, C29, R42 and R54 do? Are they for damping of output voltage transients?
These chains form the PSU frequency correction. This is a very delicate question. If we use a differential amplifier to produce a voltage feedback signal, then we have no right to connect the frequency correction circuit to the PSU output. It can only be connected to the output of the differential amplifier. The required depth of the correction can be achieved only in the case of inverting error amplifier (see. Agilent scheme). But this complicates the PSU. So I compromised - has set up two symmetrical frequency correction chains, bypassing the differential amplifier. In general, all questions about frequency correction is better to look at PSpice, where I spent a lot of time.
What do C51 and R98 do? Are they for damping of CC to CV transition?
This chain was added later. It eliminates the overvoltage in the transition between the two levels of current in CC mode. Initially, in the simulation, I missed that. The action of the chain shown in the figures below.
[/list]
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I like the design a lot. I may borrow a few ideas for my own projects.
That said, I hope someone out there will put this (or something similar) together in kit form for purchase. I'd buy one.
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hope someone out there will put this (or something similar) together in kit form
Hi Inteljoe,
I am working on this. PCBs and some components are already available, but I am not ready to send full kit yet. Will keep you informed.
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Firmware update - version 2.04.
Fixed setting of V, I values and OVP, OCP, OPP thresholds for TOP_V more than 36 V or TOP_I more than 4 A.
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Hi there Liv, let me tell you: this is a great project!
I have started one for myself [ https://www.eevblog.com/forum/beginners/mosfet-linear-regulator-circuit/ (https://www.eevblog.com/forum/beginners/mosfet-linear-regulator-circuit/) ] which I would like you to take a look at it and help if you can. I hope I can get enough knowledge to complete it! that thread contains the main mosfet regulator circuit only, other stuff will be added later as my problem is that it is not stable and I can't get it to behave well in low currents below 80mA as well as it doesn't accept input voltages higher than say 3v of output voltage which is just funny.
anyway, I have some questions:
1- where is the main regulator transistor in your design? I didn't see it.
2- please tell me how did you make it stable? I mean the diode+caps+resistors in every feedback loop and op-amp circuit. This is a nightmare for me right now as I don't know how to choose them.
3- how did you make it behave well and stable in low currents like 1mA range?
4- what is the drop voltage of your linear regulator (I aim for 1v only to make it efficient, may not be good for dynamic loads).
5- your voltage sensing is interesting. is "remote sensing" the default way or is it an option? I see resistors from out+ and out- to the diff amp but I don't know their job.
6- You used TL082 opamp for critical stuff like current diff amp, is it sufficient? in my thread they suggested LT1678 which is a lot pricey. as for comparator op-amp they are not critical thus something like lm358 or lm324 is good enough in my opinion. As for TL072 they suggested not using it because it will need a negative voltage rail unlike single supply ones like LT1678.
I have some ltspice circuits in my thread but none of them is stable over the whole range. I appreciate your help and looking forward to learn skills like yours.
your friend,
VEGETA
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1- where is the main regulator transistor in your design? I didn't see it.
I am using the stacking transistors in order to reduce power dissipation. This is equivalent to switching voltage ranges, but it happens automatically and quickly.
2- please tell me how did you make it stable?
Sleepless nights in the PSpice.
3- how did you make it behave well and stable in low currents like 1mA range?
I do not see any problem with small load currents. Sometimes, problems may arise from loads that have a complex impedance. In such cases, my PS is not stable, due to the absence large capacitor at the output. But this capacitor can be added directly to the output terminals, while PS becomes stable.
4- what is the drop voltage of your linear regulator (I aim for 1v only to make it efficient, may not be good for dynamic loads).
I have a multi-level power, if we take the intermediate levels, the minimum drop is very small. But at the upper level it reaches of several volts.
5- your voltage sensing is interesting. is "remote sensing" the default way or is it an option? I see resistors from out+ and out- to the diff amp but I don't know their job.
Remote sense is optional. My copy of PS without separate sense terminals. The sense signal is internally connected directly to the output terminals. But you can make separate terminals. The resistors are needed to ensure that when broken sense wires output voltage does not greatly increased. This is a standard solution that can see the circuit Agilent PS.
6- You used TL082 opamp for critical stuff like current diff amp, is it sufficient?
This choice has been made to reduce the cost and simplify the search component.
in my thread they suggested LT1678 which is a lot pricey. as for comparator op-amp they are not critical thus something like lm358 or lm324 is good enough in my opinion. As for TL072 they suggested not using it because it will need a negative voltage rail unlike single supply ones like LT1678.
My scheme will not work with a single supply with any opams. Such a scheme can be done, but I do not aspire to it. PS quality will be worse. Get the negative power supply is very simple with the main winding, I just connected a rectifier bridge through capacitors.
I have some ltspice circuits in my thread but none of them is stable over the whole range.
That's a very difficult question. When calculating the stability of the circuit need to use load parameters. For a power supply they are not known, because the load can be any. Therefore, to make stable power supply is impossible in principle. For example, Agilent draws graphics with PSU stability area for different load inductances and capacities.
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I am using the stacking transistors in order to reduce power dissipation. This is equivalent to switching voltage ranges, but it happens automatically and quickly.
You mean VT11 to VT14? while VT7 is the gate driving transistor? if so, then they are in series with each other.
Then it is fed from "out" to "out+" and "out-" which are the true output terminals while the current sense resistor is connected between out- and the true ground, right?
Sleepless nights in the PSpice.
On that we agree xD.
I meant for example, why picking 10nf+10kR as compensation (with that diode like VD19), instead of 1nF+10KR or something else? is it trial and error or is there a guided method for doing so? both will yield sleepless nights as well. I don't have PSpice thus I will rely only on LTSpice.
I do not see any problem with small load currents. Sometimes, problems may arise from loads that have a complex impedance. In such cases, my PS is not stable, due to the absence large capacitor at the output. But this capacitor can be added directly to the output terminals, while PS becomes stable.
it is common to have this low currents issue, I mean when you put a current limit of 10mA or so... not when it is in CV and the load draws 10mA. By large capacitor do you mean something like 100uF aluminum (electrolytic) capacitor? or do you mean you have some circuit to add it when necessary?
What is the minimum load current that your supply can set in CC mode? does it suffer from high capacitive or inductive loads?
I have a multi-level power, if we take the intermediate levels, the minimum drop is very small. But at the upper level it reaches of several volts.
You mean V1,V2,...etc rectified from the transformer taps? But you still got to pick an output voltage and this is where the drop is determined.
Remote sense is optional. My copy of PS without separate sense terminals. The sense signal is internally connected directly to the output terminals. But you can make separate terminals. The resistors are needed to ensure that when broken sense wires output voltage does not greatly increased. This is a standard solution that can see the circuit Agilent PS.
As far as I can tell, out+ is connected to R83 and R84 in series... after that it is "sense+" which is fed into R70 and R61 in series which form the positive input of the op-amp (and the same for the negative one) while R57 is for the gain. R75+C33 are compensation for stability.
Now what I meant is why not connecting "sense+" directly to the out+ since it gives /10 gain via the op-amp? why there are R83+R84? without this you won't be able to sense the voltage thus what is the remote sensing here which is optional? you mean the "sense+" and "sense-" external connection via XP3 (to be able to sense the voltage outside of the supply)?
My scheme will not work with a single supply with any opams. Such a scheme can be done, but I do not aspire to it. PS quality will be worse. Get the negative power supply is very simple with the main winding, I just connected a rectifier bridge through capacitors.
And why is that? what is the gained benefit of using negative voltage rail? and why it will be worse quality supply? someone mentioned that it will be slower CC response with single supply op-amps like mine but I don't know why while your design seems fast which gave you the freedom to pick lower quality op-amps. Is there a reason for this?
That's a very difficult question. When calculating the stability of the circuit need to use load parameters. For a power supply they are not known, because the load can be any. Therefore, to make stable power supply is impossible in principle. For example, Agilent draws graphics with PSU stability area for different load inductances and capacities.
And how stable is yours? people mentioned the trials of putting different types of loads especially low current ones and high capacitive ones as well as pure inductive loads. So you mean I should finish the design then try these loads one by one?
As for stability, I just learned stuff about ac analysis with bode plots and it does seem the key to make power supplies stable. what points do you test to determine that?
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thanks!
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You mean VT11 to VT14? while VT7 is the gate driving transistor? if so, then they are in series with each other.
Then it is fed from "out" to "out+" and "out-" which are the true output terminals while the current sense resistor is connected between out- and the true ground, right?
Yes.
is it trial and error or is there a guided method for doing so?
I watched the phase margin for different loads. It was necessary to solve complex optimization problem that just happened by trial and error.
By large capacitor do you mean something like 100uF aluminum (electrolytic) capacitor?
Yes. Most PSUs are 470 uF output capacitor. I would do without it.
What is the minimum load current that your supply can set in CC mode?
1 mA, it is limited by the resolution of DAC. Analog circuit can provide arbitrarily small current (within the OPAmps errors, of course).
You mean V1,V2,...etc rectified from the transformer taps? But you still got to pick an output voltage and this is where the drop is determined.
I do not understand what the question is.
Now what I meant is why not connecting "sense+" directly to the out+ since it gives /10 gain via the op-amp? why there are R83+R84? without this you won't be able to sense the voltage thus what is the remote sensing here which is optional? you mean the "sense+" and "sense-" external connection via XP3 (to be able to sense the voltage outside of the supply)?
My copy of the PSU has no external sense terminals. XP3 internally connected to the Out + and Out-. In this case, the R83-R86 are not needed, as VT11 and VT12. But if you add external sense terminals, these elements are desirable.
what is the gained benefit of using negative voltage rail? and why it will be worse quality supply?
In single supply PSU is difficult to provide a precise work near zero voltage or current. Since even the Rail-to-Rail op amp output voltage can not reach the ground. It will be necessary to shift all the signals. I also shifted the signals, but for a different reason - unipolar DAC and ADC can not be calibrated at zero.
And how stable is yours?
I use the PSU for almost 3 years, during which time the two times met the oscillation. And it was not inductive or capacitive loads. For example, when connected as a load current source using MOSFET. It was necessary to add a capacitor on the output. I can not do absolutely stable PSU.
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Hi Liv,
This is a nice power supply, well done! I have no insights in the software (yet!), but the design and execution of the hardware is impressive! I have two (small) questions here:
The toroid is custom manufactured I guess?
Toroid based on 105W transformer for halogen lamps. Secondary winding (12V) was removed and replaced by 4 windings 2 x 8.5V and 2 x 10V.
Why are the voltages different for the two sets of windings? Why not make them all ~9V? Just wondering. If one has a transformer custom made it might be easier if all windings are the same number of turns (AFAIK they are usually wound together, thats why I'm asking).
This is how it seems they wind toroids:
video (https://www.youtube.com/watch?v=82PpCzM2CUg)
If you do a precision power supply, it must be purely linear. Or use low-noise preregulator working at mains frequency. An example of such amateur PSU with 1 mV step here (http://koyodza.com/PSA2/index.php?lng=EN).
Is this yours too? I am seeing the same style of case here... ;-) It looks like they sell this case in in NL too, they seem to be dirt cheap (<€2,00 for 5+). Don't know the difference between Z-2A and Z-2AW, but I might just buy one and check what I'll get. ;D I have had issues finding decent affordable cases here, so this is good news.
Really respect the work you did!
Regards,
Crumble
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Why are the voltages different for the two sets of windings? Why not make them all ~9V? Just wondering. If one has a transformer custom made it might be easier if all windings are the same number of turns (AFAIK they are usually wound together, thats why I'm asking).
I wind the transformers myself, so it does not matter what the windings are. The design of the PS allows the use of identical windings.
(http://ic.pics.livejournal.com/leoniv/12037956/599397/599397_900.jpg)
Is this yours too?
No. This project was made by one developer from Ukraine.
they seem to be dirt cheap (<€2,00 for 5+). Don't know the difference between Z-2A and Z-2AW
The quality of these cases is not very good, but it is adequate to such a price. Typically, the letter W denotes the presence of a ventilation.
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I wind the transformers myself, so it does not matter what the windings are. The design of the PS allows the use of identical windings.
Is the handwinding the reason the windings are different, or did it have some technical relevance? I can imagine the dropout of 4 mosfets (when outputting a high voltage) is more than for only 1 (at low voltages), and that you would use the higher voltage windings for the higher ranges to compensate. I could not find the way the windings were connected in the schematic though. It is good to hear the supply is not critical about some variation in voltage. I think serge_m must have noticed this too preparing the kit he proposed making.
The quality of these cases is not very good, but it is adequate to such a price. Typically, the letter W denotes the presence of a ventilation.
Ok, that is usefull to know, at least I won't have to worry about the size. Think I'll order one and check how I like it. I bought a case from Banggood (http://www.banggood.com/Electronic-Plastic-Shell-Cartridge-Handle-Project-Case-Desk-Instrument-200x175x70mm-p-1035473.html) recently, but the quality of the plastic was only mediocre, it had minimal ventilation slots and it had some play in it. It also took €10 rather than €2, so even if this case is the same quality I'd be quite a lot better off.
Regards,
Crumble
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Is the handwinding the reason the windings are different, or did it have some technical relevance?
In theory, this PSU structure allows you to arbitrarily select all 4 voltage levels. In practice, the lowest stage is used to obtain a voltage of 5 V, it must provide this taking into account the drop on the LM317. Another limitation is the simplification of rectifiers - pairs of windings should be the same. If completely separate rectifiers are used, this requirement is eliminated. The voltage levels of the individual stages can be selected based on the practical conditions for using the PSU. When the output voltage is close to the voltage of one of the stages, the power dissipation is minimal.
I can imagine the dropout of 4 mosfets (when outputting a high voltage) is more than for only 1 (at low voltages)
In a linear PSU, the voltage drop across the pass transistor is much higher than on an fully open transistor. Therefore, the additional fully open transistors in the chain have almost no effect.
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Hi everyone, and thanks Liv for sharing this awesome project. I have wanted to build the PSL-3604 for quite some time.
I have already gathered all parts, soldered PCBs, flashed STM32 and I am left with winding my transformer, wiring it all together and screwing it to heatsink (I also have the same Z-2AW enclosure).
So I have a question regarding the transformer windings.
Do I understand correctly, that those recommended "2x 8.5V" and "2x 10V" windings as You have mentioned should be 8.5V and 10V in amplitude when the maximum load is applied? So that after synchronous rectifier and filters, the highest tap would be (close to) 37V with respect to GND and that there would be 1V headroom for 36V regulation. Is this high enough for losses in the path and operate normally ?
Or should I actually wind ~8.5V and ~10V windings (effective value), such that after filter caps the highest tap would be around 2 * (8.5V + 10V) * sqrt(2) = 52.3V ?
And if my transformer allows such power, could I potentially go (by rewinding transformer) from 36V to for example 40V (as long as the output protection diode allows it and I am able to modify firmware accordingly) ?
Cheers,
Zigmars
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My transformer: 2 x 8.6 V + 2 x 10.2 V effective without load. Rectifiers out: VN = -13 V, V1 = 11.1 V, V2 = 22.4 V, V3 = 34.8 V, V4 = 47.2 V, VG = 58.6 V (all boards connected, no output load).
You can make any voltage stages. The first stage V1 should provide sufficient voltage for +5 V regulators. The rest can be chosen arbitrarily. The maximum output voltage, which is supported by program, is 99.9 V. But you need to change the gain of U9: 1, so that the full scale corresponds to 3 V at U9:1 output. The same is true for the current scale, which can be up to 9.99 A.
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Olá, não sou muito experiente na eletrônica to apenas começando e too precisando de unidade de fonte de alimentação gostei muito do seu projeto tá de parabéns tou pensando em fazer passo a passo. essas pci você fez manualmente ou mandou fazer numa fabrica especializada em pcis é possível fazer em casa.
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The boards for the PSL-3604 are made at the factory. But I made boards for similar PSL-2401 and PSL-2402 manually using a laser printer and an iron. For beginners these PSUs can be too complicated.
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Olá amigo esse display de 7 seg onde você comprou eu não acho ele é catodo ou anodo o buzzer eu não acho nem um deles da lista que você deixo em loja nem uma
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7-seg LEDs - common cathode.
Buzzer either of the two shown in the schematic diagram.
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Olá amigo vou manda fabrica as minha placa pela seeed studio ou easyEDA mais o aquivo gerber não funciona não aparece as medidas ta dando erro por que o arquivo gerber
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I dont know. These gerber files were given to the PCB manufacturers in Ukraine, everything was fine. You can try to send the PCAD-2006 files to the PCB manufacturer.
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Hello friend, how are you? these leds REC-S3461CG-G / REC-S3461CSR-G has no where to find it does not have the easiest model to find that I can use psl-3604 this leds is a special model thanks...
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Any leds with a common cathode and suitable dimensions will work. For example, Toyo E40361-L.
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Thank you very much for sharing this great project. Congratulations. :-+
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Hi!
Afternoon Liv, how's the LD8020 Electronic Load Project getting along?
I'd love to make your completed design rather than buy a Chinese one - in my opinion, Chinese gear needs to be taken apart, examined for safety issues and corrected where necessary, a set of schematic diagrams drawn out and a B.O.M. written up (and if possible!) the firmware extracted before it can occupy a permanent lab place in my opinion, whereas all your excellent projects have all the documentation on hand before you begin!
Chris Williams
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Unfortunately, the LD-8020 electronic load project has not yet progressed. Now I have difficult times, there is no way to do hobbi projects.
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Hi,
I really like the power supply design, specs and the simplicity. Thank you for sharing the all the details to us and its really very helpful to understand working of it. Please keep such a good work up :box:.
May I know that is that product still active and where can I buy that (online)? Is it available in India anywhere please?
Cheers,
- Pradip
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I made this product for myself in one copy.
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That Is a beautiful project Mr. Live, and I too would be interested in buying one if it becomes available. Price considered of course.
Best,
George KG5TKY
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Hallo Mr. Liv and all who follow this tread.
I'm looking for someone who has a spare set of PCB's that i can purchase?
If no one has, then maybe someone is willing to place an order for a small production together to minimize cost and waste?
Third option would be for someone to be wiling to purchase a finished PSU or a kit from me?
Any help would be greatly appreciated.
Thank you all in advance :-+
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Oof, I would have loved to, but I'm in Belgium and my experience is that sending stuff through Europe usually turns out more expensive than just placing two individual orders from China. If I were you I'd just order at a cheap Chinese manufacturer, and sit back and relax.
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Yes, i think you are right. I found a thread on the topic on the best and cheapest places to buy PCB's and have found a very affordable site in Japan. On top of that they actually have almost all the parts even though a lot of them are obsolete.
Anyway, i should receive some bords and parts in the near furture if anybody should be interested in PCB's, a full kit or a completed PSL-3604!
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In Japan? :o That kind of surprises me, I guessed it would be a Chinese site like seeedstudio (https://www.seeedstudio.com/fusion_pcb.html) or jlcpcb (https://jlcpcb.com/). Which site are you using?
Which parts do you see which are obsolete? Most parts either have a more modern equivalent or are still available. I don't see that many outdated parts to be honest (but I did not check the entire BOM for availability, bit tedious ;D).
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I would be interested in set of PCBs (if price is right). (EU-Germany)
;)
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I am checking if I can get a set of boards made now for the fun of it, and two details came to my attention:
- The voltage is too high for the rectification MOSFETs, they are rated 25V, but with 10V windings the'd have to cope with >28V, so I consider that risky and will use 30V parts and try to make the transformer 4x8V or so. I will likely use the 30V IRLR8726, which is very cheaply available at lcsc.com: product link (https://lcsc.com/product-detail/MOSFET_International-Rectifier_IRLR8726TRLPBF_International-Rectifier-IR-IRLR8726TRLPBF_C67280.html);
- The holes for the spade terminals are too small, most I can get here (at Farnell: search link (https://nl.farnell.com/c/connectors/crimp-terminals-solder-terminals-splices/pcb-terminals?tab-size-metric=6.35mm-x-0.81mm)) require a 1.4mm end size. I don't have any terminals with this smaller hole size and had issues finding any, therefore I will modify the final design to have larger holes.
This does not mean I am not impressed with the execution of the PCB! :-+ It is a relatively complex design, but the PCB can be produced very easily (0.3mm min track width, 0.2mm isolation distance, 0.6mm minimum hole size, any PCB producer can do this). The legend is organised and all reference designators are printed and there is the facility for multiple variants of some parts.
This is just a hobby thing for me, so future progress may be slow and haphazard, but I thought to start out doing the basic checks and modifications to the design and share my thoughts with you. I will certainly upload a picture when I get around ordering the boards!
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What would be the cost to make this power supply?
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Depends... I have not made a complete BOM yet, and some of the custom parts (mainly the transformer and mechanicals) will be very dependent on where and how you get them. It will not be cheap if you have them custom made. I had a single set of PCBs made here at a supplier I know, but for one-off quantity the PCB would have cost me €100 at regular prices, which may be rather steep. A 225VA transformer (the type that you should use for this design, the one Liv used is actually a bit underrated*) easily costs €50 new, and you will still have to rewind it.
On the other hand, if you can use an existing enclosure with a scrap transformer and cooling you can save a lot of money. I will check if I can get the panel I now ordered here in Europe made cheaper in China (which is quite likely), but the PCBs in a panel are about 150x200mm, so the surface area will count in the final price. I will disclose this information as soon as I have it, but at this point I did not do the boring administrative work yet. ;D
What kind of budget are you on?
*edit: I think the design has a derating system for higher voltages.
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Update: I ordered parts at LCSC, and they were underway for just over a week until they got stopped by the Belgian customs... Paperwork and delays. :blah:
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I had these PCBs made into a panel and I attached the design files to the post. These are .dpf files, they should be readable by any PCB production company.
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Hi Leonid,
I have a question regarding the control loops of the EEZ H24005 Bench Power Supply
What's the advantage of IC5A that sink current, instead of the traditional way where an OP-AMP drive the base of a transistor? Stability?
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Hi there, I haven't heared from Liv for quite a bit, so I don't think he'll reply anytime soon.
But why are you asking this question about an unrelated power supply here? It seems to make more sense to create a new topic with the proper subject, so other people that may know it will recognise it and provide a useful answer.
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Do you think it would be able do build with 2 transformers instead of rewind one?
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One could as well use 2 seprate transformers. Usually 1 larger transformer is a little more efficient, as the power rating about scales with the weight to the power of 4/3. However the difference is not hat big. Transformers with just 1 split seconondary are a lot more common than with 2x split.
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JLCPCB does not open files :(
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Someone asked me about PSL-3604 synchronous rectifier simulation I posted a long time ago on another forum where access is limited. Here I put it in the attachment so that it can be downloaded freely.
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JLCPCB does not open files :(
That's a shame, I did not anticipate that. I will have to check if a converter between .dpf and .gbr files exists, it should have a similar format. I am not giving any guarantees though... :-[ I will let you know when I know more.
Regards.
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Hello,
Can someone please share the LTSpice simulation files