Low Cost PCB's Low Cost Components

Recent Posts

Pages: [1] 2 3 4 5 6 ... 10 Next
1
Beginners / Re: 20v 10A PSU Weirdness
« Last post by FotatoPotato on Today at 05:35:24 PM »
Ok, thanks for the reply. I will make the modifications you pointed out and ill come back to you if it works. And yes I did change the sense resistor, it is 0.1 \$\Omega\$ now and it is in a TO-220 package so that I could mount it directly to the heat sink. Also will I need to get a large power resistor for the 0.22 \$\Omega\$ resistor or will it not pass much current.
2
Also, I think that the optimizations in question are mostly part of the original GCC, not something added by Microchip.

Quote from: technix
Even if it is added by Microchip, the second it is added into GCC code tree it is subjected to GPL

Quote from: Karel
There does not exist something like a "licensed Microchip XC compiler" for PIC16

Unlike all you internet lawyers, I have neither the training nor sufficient knowledge of how Microchip implemented their license scheme to give reliable legal advice on the subject. However Microchip obviously thinks they have a right to enforce their licenses, and I bet they had actual lawyers check it out. Are you willing to challenge them in court?

But hey, if you think you can get away with it then crack away! Then when Microchip moves to fully proprietary pay-only software with onerous EULAs I will know who to blame.
 
3
Beginners / Re: 20v 10A PSU Weirdness
« Last post by not1xor1 on Today at 05:28:57 PM »
Each transistor has slightly different characteristics, vbe, hfe, etc.

You cannot just connect each terminal in parallel  :palm:

you have to put a power resistor (0.22-033\$\Omega\$) on the emitter of each transistor and then connect the other terminals of the resistors to a common point that has then to be connected to the current sense resistor.

The resistors will provide some feedback so that if a transistor has a lower Vbe and let pass more current the voltage through its emitter resistor will increase and will so reduce Vbe so that all transistor at the end share about the same current.

BTW I hope you changed the current sense resistor, 10A squared * 1\$\Omega\$ are 100W.  :scared:
4
Beginners / Re: 20v 10A PSU Weirdness
« Last post by glarsson on Today at 05:25:30 PM »
They are all linked together identically and all their bases are connected as well.
This is not the way to add more pass transistors. They will not share the current equal.

Continue looking at other designs and you will find that they use, for example, small value emitter resistors to balance the currents.
5
Projects, Designs, and Technical Stuff / Re: 150V 1A voltage booster
« Last post by blueskull on Today at 05:25:05 PM »
Does it have an at least 200V MOSFET? Does it have at least 160V output capacitors? Is its voltage sensing resistor 150V+ rated?
6
EEVblog Specific / Re: EEVblog #1039 - Keysight Metrology Standards Lab
« Last post by tautech on Today at 05:17:33 PM »
Very nice video!
Dave, you should go back there and make a similar video about each of the calibration divisions in the lab.

Well they have actually invited me back to bring a bit of kit and film the whole (likely boring to most!) process of having it calibrated.
I'm not sure how exciting a video that would be?
To some boring but to most informative.
But what to take ?

Your best kit (for personal standard usage) or some relatively new equipment to check how accurate factory calibration might be.
7
Beginners / Re: 30v 10A bench supply schematic. Is it any good???
« Last post by FotatoPotato on Today at 05:08:55 PM »
So I just finished building the 0-20v 0-10A linear power supply. Everything works flawlessly and it is almost perfect. If you look at the schematic that I linked you can see that the main transistor is a TIP142 Darlington BJT. The original schematic is only rated for 1A but by adding 4 of them in parallel you can obtain a 10A output. So I did that, the only problem is that only 2 of the BJT's work at any given time. Even weirder is that its random. If you look at a pic of the PSU you can see that they are in groups of 2 (2 on the left and 2 on the right) and randomly only one of those pairs of 2 will work. They are all linked together identically and all their bases are connected as well.

So I have no idea why this is happening, maybe you do. If you have any advice on changes to make for all 4 BJT's to work please let me know!  :)
8
Projects, Designs, and Technical Stuff / 150V 1A voltage booster
« Last post by xmen on Today at 05:06:35 PM »
There is a DC-DC boost module that can deliver upto 10A. But it can only do 80V max and my question is, can I modify it to increase the output voltage upto 150V. And only draw 1A.

Since this module uses UC3843, I believe I can modify the resistor values to adjust the output. But before I do that, I would like to know, will there be any problem ?

Input voltage is 24V.


here is the link to module https://www.ebay.com/itm/10V-60V-to-12V-80V-600W-10A-Boost-DC-DC-Converter-Power-Supply-Step-up-Module/222649153345
9
Hi I got one DC power supply. I set at 24V and current limiting at 2 amp and load is 24V and current draw set 1.5 amp so power supply should work on CV mode but if I check voltage at load it is less than 24V My question is CV mode not working? Display show 24V but voltage across load is less than 24V so what is the meaning of CV mode.  Thanks in advance.

But you have tried to set the power supply at 24 V and the load at 24 V both at the same time. You cannot do that. You have two devices that both will try to regulate at 24 V. You cannot have two control loops trying to regulate to the same value. They will fight each other.

If you want the power supply to regulate in CV mode, set the power supply voltage to 24 V and turn off the current limit (set it to maximum). Now you want the load to regulate in CC mode, so set the load to a current limit of 1.5 A and turn off the voltage limit (set it to maximum). Then you at least have a chance of the setup doing what you intend.
10
Dean2
I got your PM about this product I know little about so all I can offer is to ensure the firmware is the latest version.
Further, when triggering is unstable and settings are apparently correct, examine the period of the 'triggered on' signal and add some trigger holdoff to ensure you do not trigger again until the next event.
Sometimes a 'Single' trigger setting is enough to get the detail/info you need.
Pages: [1] 2 3 4 5 6 ... 10 Next