EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: Terabyte2007 on June 18, 2016, 01:55:55 pm
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I thought this could be handy so I picked one up! It's a small handheld PS with a large bright easy to read screen, decent V/A capability and so far in my testing surprisingly stable. It supplies 0 - 3.75A @ .3 - 30V. It has two USB ports with adjustable current and fixed voltage @ 5.10V. The controls are pretty easy to navigate and the small multimeter compact size is great! Since I have only had a day or so to test, For 99 US dollars, its not a bad deal for what you get! I'll post a follow-up to this with some more results. Here is the Amazon link below:
https://www.amazon.com/Tekpower-TP3016M-Portable-Handheld-Variable/dp/B015OA1J82?ie=UTF8&ref_=cm_cr_arp_d_product_top (https://www.amazon.com/Tekpower-TP3016M-Portable-Handheld-Variable/dp/B015OA1J82?ie=UTF8&ref_=cm_cr_arp_d_product_top)
It also claims to have a software calibration mode with some basic cal instructions in the manual.
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That looks interesting and useful. As a portable though - it would be even more useful if it had a battery powered option - at least for the lower voltages.
I've been impressed by the Tekpower multimeter I own -for the low price the accuracy and build quality is impressive. I'll look forward to more info. How about a teardown?
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I've been impressed by the Tekpower multimeter I own -for the low price the accuracy and build quality is impressive. I'll look forward to more info. How about a teardown?
I'll see if I can do a quick teardown with some pics this week.
Eric
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Terabyte2007 , if it's not too much trouble can you also zoom in on the output of the ac switcher if there is one?
I like the idea of these gadgets but its only 110v ac in for you people over there , checking the ac switcher output might give us the info needed for running off cells or some type of battery setup (it would have to be "over" 30vdc i guess) .
The above really is if TP do not make a 240vac in one of course .. , cheers ...
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Terabyte2007 , if it's not too much trouble can you also zoom in on the output of the ac switcher if there is one?
No problem! I'll try and get to it today if not tomorrow.
Eric
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+1, would be nice to see if there's a way to switch it to 220V operation by changing a link or so (it is sold under the Velleman brand in 220V version, but at twice the price).
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An interesting product.
For me, an internal picture is a must in order to assess the design and quality. You have to have confidence in a power supply as it has the potential to fry the kit you connect to it.
I like the compact format that breaks the mould of bulky bench power supplies, but I suspect that this is just the next logical step on from universal variable voltage laptop PSU's that are now common.
I found the 220v version of this unit available for sale in Germany at 199 Euro's so it looks like the US version is the one to go for if it can be changed to a higher voltage input. Much depends upon the input circuit configuration.
I look forward to hearing more about this unit
Fraser
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I look forward to hearing more about this unit
Fraser
I agree! Sorry for the delay, I have been extremely busy since the last post and have this on my todo list! I'll try and get to it by the end of this week...
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A review is here:
https://www.youtube.com/watch?v=dI4i4TVhkF0 (https://www.youtube.com/watch?v=dI4i4TVhkF0)
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Wow, looking forward to your teardown. It looks like it could be really handy!
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Same thing seems available in Europe under different branding
http://www.circuitspecialists.eu/power-supplies/handheld-power-supply/portable-handheld-switch-mode-variable-dc-power-supply-with-lcd-display-0-30v-csi-2002h/ (http://www.circuitspecialists.eu/power-supplies/handheld-power-supply/portable-handheld-switch-mode-variable-dc-power-supply-with-lcd-display-0-30v-csi-2002h/)
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Wow, looking forward to your teardown. It looks like it could be really handy!
I'm looking forward to some tear down photos as well. I'm curious how easy it would be to add battery power.
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Same thing seems available in Europe under different branding
http://www.circuitspecialists.eu/power-supplies/handheld-power-supply/portable-handheld-switch-mode-variable-dc-power-supply-with-lcd-display-0-30v-csi-2002h/ (http://www.circuitspecialists.eu/power-supplies/handheld-power-supply/portable-handheld-switch-mode-variable-dc-power-supply-with-lcd-display-0-30v-csi-2002h/)
Nice, good pricing too. There's a discrepancy in the specs as it both says 220-240V and 90-265V though, sounds a little fishy. Model number brings nothing.
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Just got one of these tonight and thought I'd post a few pictures of the insides. One of the pictures is the control board (top) with a thin white plastic panel to separate the delicate side from the business side. Pretty thin sheet doubt it's going to do much if something decides to pop on the high side. :scared:
Haven't had much time to play with it. Hooked it up to a load and tested maximum output (30v, 1.666A), displays for voltage and current were very accurately, spot on compared to my 34461a. Also it didn't get very warm at all after running at full load for about 15 minutes, guess that's expected with a switcher. So far seems like quite a bargain for $99. :-+
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Good to see a conventional fuse plus a self resetting 100C thermal fuse in the supply input.
The input capacitors are rated at 400V and there are 2 of them. This makes me wonder if the unit has a conventional 110/220V input design.
Regarding the safety barrier insulator plate. Much depends upon the material used as some very thin materials can still be very effective in this role.
Fraser
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Thanks! Is that supposed to be the 110V Tekpower version?
I should be receiveing a 220V version, but that on the same page also had a 90-265V rating pretty soon for comparison and trying to find out what's what in the end... hopefully the below is right :)
The input capacitors are rated at 400V and there are 2 of them. This makes me wonder if the unit has a conventional 110/220V input design.
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Really doesn't look that bad, will definitely get one! Do have a strong itch in my fingers to replace those two Chang caps though.
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Same thing seems available in Europe under different branding
http://www.circuitspecialists.eu/power-supplies/handheld-power-supply/portable-handheld-switch-mode-variable-dc-power-supply-with-lcd-display-0-30v-csi-2002h/ (http://www.circuitspecialists.eu/power-supplies/handheld-power-supply/portable-handheld-switch-mode-variable-dc-power-supply-with-lcd-display-0-30v-csi-2002h/)
Nice, good pricing too. There's a discrepancy in the specs as it both says 220-240V and 90-265V though, sounds a little fishy. Model number brings nothing.
Have ordered one anyway, and it just got there. It's specced at 90-265V on the box and appears mostly identical inside to msquared's, but there are a few subtle differences on both PCBs, and mine doesn't have the thermal fuse, his seems to be the newer rev as the marking on the control PCB suggests. Solder pour on the bottom is a bit meh, looks like a volcano >:D
I like the detailed silkscreen, seems whoever wants battery power with full capabilities might need to supply 38V.
Photos here:
http://s18.photobucket.com/user/Kilrah/library/PSU (http://s18.photobucket.com/user/Kilrah/library/PSU)
After taking it apart I also turned it on ;) , and it's really pretty good from the basic testing I can do here i.e. accuracy of the voltage and current measurements and load regulation, no good scope here but that was already looked at anyway. The software DOES use max power to set the envelope i.e when setting current limit to the 3.75A max then increasing voltage you'll see the current limit gradually go down, no "big step" as specs could suggest.
Could find a little bug, the 5 memories default to "-0.01" both for V and A, if you load one then press SET and UP to increasse voltage the current limit will set itself at 5.005A. I've put a photo with my startup screen that seems to show the SW rev for comparison.
When output is off voltage is around -0.35V, but will only push 0.17mA so shouldn't damage anything.
All the secondary side control seems to be done on the "user interface" PCB by an STM32F100, the silkscreen says what the helper comparators/opamps are used for and the interface to the PSU board as well as the SWD port and a serial interface are all labelled, so it seems like it could be a perfect candidate for some alternative firmware development ^-^ :popcorn:
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...aaand it's perfectly happy to run on DC, dropout under 20W load is just under 2V :)
The 2 photos below were taken with a 16V input. Neither the switcher nor the controller complain when asking for a higher voltage than it can achieve ^-^
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Thanks for the pictures msquared and Kilrah?
Looks like there's plenty of room to add a power on/off switch. And easy to battery power...
Hmm, may have to get one of these.
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Looks like there's plenty of room to add a power on/off switch.
Actually came across one that's not to badly suited in a drawer while looking for something else... bit crude, but meh
Seems like I might be able to fit an XT60 DC plug on the left side just below the board to board connection, but that would be a pain to hold in place, more thinking needed
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Very good thread. Thank you guys.
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You can add this to the power cable.
UK 6A/250v Inline Lamp Lighting Light Rocker Through Switch
if you not happy with cutting the enclosure:
http://www.ebay.co.uk/itm/like/UK-6A-250v-Inline-Lamp-Lighting-Light-Rocker-Through-Switch-for-3-Core-Cable/262515283187?hlpht=true&ops=true&viphx=1&_trksid=p5197.c100068.m2280&_trkparms=ao%3D1%26asc%3D20140211125758%26meid%3D3bf1fefb3eb74d75bd23a68c3ac2cc32%26pid%3D100068%26clkid%3D119103332966092214&_qi=RTM2108002 (http://www.ebay.co.uk/itm/like/UK-6A-250v-Inline-Lamp-Lighting-Light-Rocker-Through-Switch-for-3-Core-Cable/262515283187?hlpht=true&ops=true&viphx=1&_trksid=p5197.c100068.m2280&_trkparms=ao%3D1%26asc%3D20140211125758%26meid%3D3bf1fefb3eb74d75bd23a68c3ac2cc32%26pid%3D100068%26clkid%3D119103332966092214&_qi=RTM2108002)
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Can anyone confirm if the model in amazon support 220v?
https://www.amazon.com/gp/product/B015OA1J82/ref=reviewsLightboxvoterdr?ie=UTF8&asin=B015OA1J82&noCache=1502744023654&thanksvoting=cr-vote-R1KZU7MIOH2AZ4#R1KZU7MIOH2AZ4.2115.Helpful.Reviews (https://www.amazon.com/gp/product/B015OA1J82/ref=reviewsLightboxvoterdr?ie=UTF8&asin=B015OA1J82&noCache=1502744023654&thanksvoting=cr-vote-R1KZU7MIOH2AZ4#R1KZU7MIOH2AZ4.2115.Helpful.Reviews)
Thanks!
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The spec shown in the supplied images suggests it is 110V 60Hz only.
It would be best to contact the seller to gain confirmation of voltage capability as then you have some comeback if it is only 110V when it arrives.
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Tekpower branded units are 110V only as far as we know.
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Has anyone managed to look a bit deeper at the current limit functionality?
I found in my initial testing that it would turn off output most of the time instead of holding current at its limit, depending on the load.
I also wonder if there are undocumented features when holding certain buttons.
I've been using the supply occasionally for over a year without any issues.
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Current limit is very poor, it's not a real CC like one would expect from a lab PSU. If you approach the set limit slowly it will somewhat behave like it but with very poor precision, but if you come too fast or the required voltage reduction becomes too important it just shuts off.
If I need proper CC (and more generally these days) I use RD regulators with a generic power brick I have around as source:
https://www.aliexpress.com/store/product/RD-DPS3005-Constant-Voltage-current-Step-down-Programmable-Power-Supply-module-buck-Voltage-converter-color-LCD/923042_32684316119.html (https://www.aliexpress.com/store/product/RD-DPS3005-Constant-Voltage-current-Step-down-Programmable-Power-Supply-module-buck-Voltage-converter-color-LCD/923042_32684316119.html)
https://www.aliexpress.com/store/product/RD-DPH32305-Constant-Voltage-current-Buck-boost-Programmable-digital-Power-Supply-buck-Voltage-converter-color-LCD/923042_32762131242.html (https://www.aliexpress.com/store/product/RD-DPH32305-Constant-Voltage-current-Buck-boost-Programmable-digital-Power-Supply-buck-Voltage-converter-color-LCD/923042_32762131242.html)
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On the control board there is an UART connector which caught my attention. I was hoping to control the voltage level & measure current to do some automation (e.g. battery charger over bluetooth). But unfortunately it did not respond to my requests. I have just tried to send AT commands and some random characters but without any response. It just sends some debugging messages over uart when some button is pressed:
https://gist.github.com/gabonator/946b20c0fa0aeda0a3ee96a85d7abbef
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This power supply is also being sold in the US at Marlin P Jones (MPJA.com) under the QJE brand model PS2002H. That's where I got mine.
I have accidentally erased the calibration at one point so that the voltage/current setting and readings were completely off. The manual seems to suggest using a 10 ohm and a 3 ohm resistor to calibrate the unit. However, (at least with my PS2002H), the proper resistances for calibration turned out to be 20 ohm and 6 ohm. When doing the voltage bias/gain adjustment, use the 20 ohm. When doing the current bias and gain adjustment, use the 6 ohm.
I ended up buying a 20 ohm 1% and a 6 ohm 1% 50W power resistors for this, as the test loads gets pretty toasty. After recalibrating, the output measurement and the CV/CC limits track fairly close to each other and to external meters. Better than 1% probably around 0.3% or so. Enough to be off by a few counts in current mode, and usually one and sometimes two counts in the voltage mode.
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This unit seems to be not sold anymore almost anywhere, so I wonder if there is a new model with maybe some of the things criticized here improved, anyone aware of that?
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I found it in different EU stores for about 100€ with the PS2002H model
https://de.elv.com/tragbares-labornetzgeraet-ps2002h-03-30-v-dc-0-375-a-max-124569 (https://de.elv.com/tragbares-labornetzgeraet-ps2002h-03-30-v-dc-0-375-a-max-124569)
Review from element14 that proposes a fix for the negative voltage when off
https://www.youtube.com/watch?v=HHxEYZaU2V0 (https://www.youtube.com/watch?v=HHxEYZaU2V0)
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I purchased one of these a couple of weeks back (Jaycar in Australia) as they had them on special. The reason they were on special is they are now discontinued. Whether that is just at Jaycar Australia or if the model is to be discontinued entirely I do not know.
The Jaycar device I purchased did not have the 'negative voltage' modification, so i went searching for a remedy and found this thread. Seeing as it was fairly recent I thought I would add...
This unit is sold under various names, but they all (apart from branding) look identical:
MP-3844 : Powertech
PS2002H : QJE
TP3016M : Tekpower
72-2660 : Tenma
LABPSHH01 : Velleman
If I kept looking there is little doubt I would find more.
Anyway, the -0.6 volt output when off is not a nice feature of a power supply, so I wanted to correct it. The Tekpower site says in the notes to remove a transistor and replace two capacitors with 50 ohm resistors. But the photo on their site shows 50 kilo-ohm resistors! [actually 49.9 kilo-ohm, but close enough] The video above also mentions 50 ohms, so that is what I am going to go with (by the way, these are 1206 size, which is handy to know if you need to order them).
I decided to have a bit of a play since it was the holidays, thinking the 0.6 might be caused by the fact the transistor is a standard BJT (NPN). After checking voltages I replaced it with an N-channel MOSFET, but I was surprised (and disappointed) it made no difference, and the off-output was still in the order of -0.6 volts. Dang!
The output also strangely does not remain "tied" to the internal ground of the unit when the output is switched off, and it floats up to about 9 volts.
I could not find a schematic anywhere on the web, and don't feel inclined to reverse engineer the PCB back to schematic to find out why the output is 'released' on 'output off' and why there is a -0.6 volt output when off. Maybe someone somewhere has a schematic of this thing?
Although a little noisy, it is a nice supply for portable use and will undoubtedly fill a very useful niche in my tool bag. I might even get another one.
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Not satisfied with the recommended modification, I decided the worst that could happen is a bit of smoke gets out, so I looked at the waveforms and scratched me head a bit...
[attach=1]
For a device that is completely floating, it made no sense that the output was 'released' when turned off. Why wasn't Vout- connected to the internal ground reference? When the output is switched on it is, so why not all the time? So I connected the internal GND to Vout- and... no smoke got out, and that nasty 0.6 volt offset is gone. However, the no-load output-turn-off took ages to discharge back to zero volts.
[attach=2]
The "design intent" (continuously harped on about at work) is likely for Q8 to quash the output to zero volts as soon as the output is turned off. So tombstone Q8 so the drain is free and connect it to Vout+... again no smoke, and the output discharges nice and quick.
[attach=3]
Sealed back up and we'll see how it goes long term...
PS: The silly-scope images refer to Q8-C and Q8-B, which are replaced with Q8-D and Q8-G respectively. I used an SI2308DS as I happened to have one in my parts drawer.
EDIT: Attached photos of mod.
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Tested my PS2002H using several voltage settings: 5V, 12V, 19.7V, 30V. Both with and w/o load (resistors, max 3A). Max ripple, measured with Hantek DSO 1202B (running on battery) with 20MHz filter was ALWAYS <20mV, which adheres to specs.
So, noise results vary.
PS2002H was running on 230V/50Hz, connected thru APC SmartUPS SUA 750 "line conditioner" with RF/spike eliminator (good old, not Schneider crap).
Serial number is 6078xx.
P.S. Unfortunately, -0.5V is present when output is switched off without significant (<1MOhm) load. Current supplied seems to be several milliamps only, so it is OK for me.