General > General Technical Chat
Show your favorite and most used benchtop PSU
Rolo:
My second post in this thread, on September 20 2014 my favorite PSU was a Delta Elektronika E030-3. This one is gone from the bench now and in its place is the GWInstek GPD-4303S. Great unit, four channels but only a bit bigger footprint compared to the Delta.
@Badvoc, this is the same unit as your ISO-TECH IPS-4303S, but the channel led's on the display are different, I have a clear indication of wich channel is controlled.
emax:
I can not really say which one I use most. Actually, each of my PSUs has its own work to do. Over the years I have most used this one, just because it is so very old.
It was my first PSU and I had build it myself - 35 years ago. I had no clue about design, no clue about electronics, there was no internet and no help far and wide. The only thing which was there, was an old transformer, a big 33000µF cap, a recitfier and some heatsinks.
So I looked for a schematic and scaled it to what I thought was sufficient. Since the only transistor I knew in that time was the 2n3055, I took a bunch of them and mounted them on the heatsinks I had, went for a case to 'Conrad', which was -I guess- so to say the german RadioShack. And so I tacked it all together. :palm:
BUT: It worked out of the box. It still works after 35 years, and you can short it at 25 amps. It stands like a rock with no thermal issues, for an hour as well as for a day or longer. If you switch it on, it sounds like a welding-transformer, and the noise intensifies under load.
I used it for cutting foam, charging car-batteries and everthing which neede a controlled voltage or current. I've no idea about ripple. :-DD (and don't in fact want to know it).
I decided to make some photographs, and especially for eevblog I've taken it apart after 35 years to take some pictures for you.
Please, don't berate me for the "design". I was so proud of it and It did its job for more then three decades - and still does: I sometimes use it a a source for a 500W RC-airplane battery charger.
SInce then, I have bought other PSUs, which are of course much better. I will show the most important ones in another post.
The pictures show
1. Front view. Pots: voltage fine, voltage coarse, current
2. Rear view. Heatsinks for eight 2n3055
3. right side, heatsink for rectifier
4. Inside. 35 years in the dark ...
5. LM723, self-echted pcb, load-resistors
6. Transistor provisioning with load-resistors.
7. Front plate inside, volt meter, amp meter w. shunt.
emax:
I have too many PSUs, but these are the other most important ones which I use really often or have a special relation with. ;)
First picture: With more income, I could afford a linear 2-channel supply, 2x40V/2.5A, separately, parallel or serial. I still have it in my workshop and use it for many purposes. In that time, it was a hell of money for me. I used this one most for my beginning electronic carreer (though I am still an analog-agnostic).
Second: A decade ago, I started with electric RC-airplanes. They are real power devices and slurp up to 200 Amps of current (even more, but these guys are a different league). So I needed a bigger supply for battery-charging. It is a switched supply from "Elektro Automatik", a german high-quality brand. The supply is frequently used for charging and can provide 0-80V with currents from 0-60A at a maximum output of 1500 Watts. To load two or more 22V LiPo batteries of 15Ah with up to 30A each is not unusual and is an easy exercise for this thing. VERY high quality, good old german engineering. Absolutely short-circuit-proof and with sense-inputs.
Third: For my work desk, I wanted a simple supply, this one delivers 0,5 to 32V, up to 2.8A. There are additional outputs with 5V and 12V. This little thingy is programmable with presets and is capable to run programmed sequences. For 128 Euro at Reichelt this is really good value for the money. The knobs are single digital-encoders, no fine/coarse separation, they only look like that but work ok. I use it often whenever I test something on the desk, arduinos, pocket-lights or whatsoever.
Fourth and fifth: My king of PSUs 8). With 10Kg of weight this is a real nugget (pun intended). I wanted four channels, programmability, and high quality - of build and of output as well. Alone the name guarantees both. FWIW: specs are here.
In face of money-devaluation this was so to say an investment and a tax-saver as well. ;)
You can set electronic fuses which switch off any dependend channel you have configured if an overvoltage or -current occurs on one "co-fused" channel. Of course, you can define arbitray signals for each single channel - independently. Every channel is capable of 0-32V and 0-10A, per channel limited to 160W. Total voltage in serial is 4x32V = 128V, total current in parallel is 4x10A = 40 Amps. The total device-limit of output is at 384W. Enough, I guess.
This thing has no touch-screen, no klicki-bunti buttons, no unnecessary gimmicks. It's a bone-dry machine and just does exactly what it's supposed to do. And it's worth every cent.
I love this hulk. ;D
JacquesBBB:
--- Quote from: Satbeginner on March 19, 2017, 05:14:18 pm ---My power supplies are both Chinese.
The linear 30V, 30V and 5V one has current limiting.
But I changed both voltage adjust potentiometers to proper 10-turn ones, so now at least I can get the values I want.
--- End quote ---
Which value are the 10-turn pots you put in. Did you changed the original 6.8k to 10 k ?
capt bullshot:
--- Quote from: emax on January 06, 2018, 08:11:23 pm ---It was my first PSU and I had build it myself - 35 years ago. I had no clue about design, no clue about electronics, there was no internet and no help far and wide.
--- End quote ---
Is it all the same with us EE's? Must have been around 1988 when I built my own lab supply - from similar prerequisites than yours.
I had a transformer, some electrolytic caps, fan heatsink and a few other components as a starting point. So I made this one from scratch:
The enclosure and digital meters were from Conrad, other parts purchased at a local electronics shop at Darmstadt (where I was an EE student then). All the electronics was build on perfboard, I didn't bother to draw a schematic diagram. Nobody told me a 250VA / 2x24V is not sufficient for a dual channel 24V / 5A lab supply, so built it to this spec. And, yes it worked. One can overload the transformer, I've attached a thermal sensor to it to keep it from overheating. I can't remember the details, but some way I've made a output stage out of 2 2N3773 and a BD139 that required only a bit more than the transistors Vbe drop to regulate, so the 24V goal was reached (with some ripple at max. current). I vaguely remember charge pump based auxiliary voltages of 5V below GND and 5V above input rail to do the trick.
The fan is temperature controlled (on/off) by temperature sensors mounted on the heat sinks, same sensors shut down the output in case of over temperature (this happens if you short the output at max. current setting).
The thing served me well until I found my way into TEA a few years ago, starting to buy fancy power supplies like the HP6632 and a quite unknown "Powerbox" that replaced my unit. It's still alive, but over the years some quirks found their way into it (e.g. the "---" display on one of the digital meters, or the not-always-working current limiting on one channel). Quite difficult to repair, since I never made a schematic and one needs to remove a lot of single wire to board connections to access the perf boards and the electronics. The voltage displays have a special feature: Auto-ranging between 9.99V and 99.9V fs range for better display resolution at lower voltages.
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