I built a +-30V supply form the "OP Amp Cookbook" back in early '80. It's right here powering my Dot Star featherwing right now (not much strain on it at 3.3v 😉). The Radio Shack power lamp has long since burned out and the switch failed in the "ON" position, but she's still cooking. These are great learning projects. Thanks for showing yours.
Subbed based on this video alone! i am trying to learn reverse engineering and component uses and this channel ticks all the boxes! i really like how you explain the different sections of the diagram in a brisk but informative way as i get easily distracted. Keep up the good work!
I used a couple of old 741's for U1 and U3, and a TL071 for U2, as that needs the offset adjustment ability. During original testing, I blew up Q4, which I thought was due to inadequate heat-sinking, but with hindsight, that may also have been a fake. I originally went for 10 turn pots, but all the ones I received from China were faulty, so I reverted back to single turn ones.
Def go with the digital gauges. Unless of course you are going for a retro look. I just like that digital ones are usually easier to see and some can be adjusted to correct limits. fun stuff no matter how you build it.
Great stuff, thanks. I love these little power supply kits, and have several. If you have UA741's (and several others), they will substitute fine for the TL081 , too. Since this "Original Hiland" circuit has been out since the '60's, there have been tons of mods to it that are out there, if you search. Did you calibrate the current with the trimmer, first? Maybe i missed that. Oh, and the pdf for construction and current calibration is available on Banggood, if you want it. I can't link to it, though, on here. These are great fun for the money and thanks for covering them. They tend to be often verbally abused, but can work great with decent components and some care.
Can you elaborate on what that trimmer is supposed to calibrate? I'm unable to see any difference in the output current or voltage at all whatsoever when I turn mine. If elaborating means copying a snippet from that PDF you mention, that's fine by me!
@@AnnaVannieuwenhuyse Try putting in your search: " Instruction of Installation of 0-30V Stabilized Voltage Supply" and then scroll through the results until you come to a Banggood result, and that should be the pdf with everything. The reason for calibration is to zero your potentiometer correctly and so that the red led indicator comes on at the right time, showing constant current kicking in. Hope this helps.
Great project, great video. Thats a nice case, should look great when done. The most common Op-Amp these days, for PSU's, is the LM 385. Even the cheap knock-offs are just as robust and accurate. I see them, and use them, in both Linear and Switch Mode units. Personally, I'm Analog Meters, but in this case we're Not eye-balling the guage every 2seconds. The Toroidal transformer, what a shame. It was perfect for this project. I'd be inclined to order another from the same store. Now the important question. Is that a Linear Power Supply, or "Linear Bench", as the title may imply. lol. Happy trails.☺
Do you mean the LM358? IIRC the LM385 is a voltage reference. I have lots of LM358s but they will not work in this design. Yeah, shame about the transformer, but I don't really have the time to wait for another to come from China on this. The Traid one I'm getting is just a regular "E" core transformer, but it should do the job. Thanks for your comments!
You can never have too many power supplies. You’ll use both types of meters eventually. I like those blue cases with the white trim. I’m not sure the one you’re using is big enough for two analog meters, along with everything else.?
Just in case anyone is interested, the TL081 op amp can be switched out with: MC3371 LF351 TL061 TL071 OP42 UA741 amongst others. So, if you have stock, these are pin compatible. Fun to try, too.
I had one of these and had the same issues I think , it was a while so memeory is a little vague. When I tried it a few months later it had almost zero output, I did try replacing TL081 but that didn't fix it or atleast I couldn't check as one of them caught fire very quickly. I do have another kit somewhere I bought it when it was really cheep but never got around to building it.
Just to be fair, this is a kit and it’s based on a Practical Electronics design that has been assimilated by others…just ensure that the transformers ac output when rectified doesn’t exceed the rated rail to rail voltage of generic op amps of 36volts…
If I'm interpreting that correctly, placing a diode from Out+ to Supply+ is the same as placing a diode across Q4's Emitter to Collector, where it clamps thje emitter to collector voltage across Q4 (output transistor) to Out+ minus one diode drop? Which would be within the safe zone of of the emitter to base voltage, preventing the destruction. Current would flow to only a minimal degree, so this could be a small 1n400x rectifier diode or a small SBD. Eager to hear if I've got this correct!
I think that I mentioned in the mail bag episode that these red board 30V/3A PSUs are (all) faulty. You have mentioned most of the known issues. Add bad traces from being copied over and over by different suppliers. I built three; all failed...
@@andymouse Yes, some YT builders have discovered trace errors. One builder bought three boards from different suppliers. Two had two different trace errors. His third board also failed. Due to fake op amps, as I recall. He was trying to find a way to identify sellers offering original kits. This was a recent review, but I forget what channel. If I come across it, I will post the details.
These kits have a very long history. I studied it out, about 10 years ago, when I was getting started. IIRC, the original design was an open post to a forum/blog/etc. It was just a prototype. The over-seas folks grabbed it up and went into production, without fully finishing the design. The under-rated/hot resistor that UB first pointed out is a known original problem that was not corrected and was carried into the rushed production. The remakers have never bothered to up its wattage. It has been down-hill, ever since, and with copies of copies, it seems to be getting worse. No guarantees on my memory. It is old and foggy.
I'm pretty sure that's the same kit as mine so I'll have to check my op amps. Do you have a link to the transformer you bought. I need a replacement so I can get the full 3 amps out of my power supply. Right now I can get about 1.5 amps max with the salvaged transformer I have in there.
If you do get a transformer, try and aim for under 24V AC. A toroidal transformer is therefor quite beneficial, as you can unwind some windings to drop the voltage if need be. This is just to save your TL081CP's from being cooked. Alternatively, fix the issue with the positive supply voltage on the op amps.
@@uni-byte I always try to get used if i can from yard sales or Ebay. I got so lucky with my biggest toroid. It's out of an old audio amp that was 2,000 watts from 220v, so i only get around 1200v from 120v (i imagine?). Anyway, it cost me 35 bucks shipped off Ebay. Amazing deal except i can barely lift the bloody thing...lol. Made a nice case for it, though.
I've always been skeptical of these cheap DIY kits from China. Seems like an easy way to make a buck by shipping them out with counterfeit or faulty surplus components and then pass the buck to the hobbyist builder for a failed unit due to implied improper assembly -- especially since they don't include schematics or instructions. I've also been looking at these boards and in some listings there's the option of buying a pre-assembled board for a couple bucks more. That's the only way I'd buy one, because then you have some refund recourse if it doesn't work... although they might still claim you incorrectly hooked up the external transformer or some other peripheral component. Of course part of the fun of these is the build itself, so I'll be following your progress to see how it turns out before deciding if I want to give it a go!
@@uni-byte Exactly. To be honest, i find the challenge of troubleshooting the problems these can give most fun, too, although, now i tend to know them pretty well, i can figure them pretty quickly. I find it best to keep a supply of my own good op amps on hand, plus a few power transistors and the big shunt resistor. Electronics Repair School has upgraded his by paralleling two of the power resistors (sorry, i meant transistors) . I must have at least ten of the boards now and all the boards work fine apart from the obvious issue with fake op amps (plus some of my own stupidities). These boards are 3.55 bucks now with free shipping (over ten bucks) on AliEx, so i think expecting them to be perfect is a bit much.
that 1/4th watt resistor surely not capable for the job. replaces it with 3x 220E when building it few years ago. and they are still shipping this with 1/4th watt ! also used a 1/2 watt for the resistor next to it. and i m not sure why the capacitor next to it popped after few minutes. just use safety goggles when testing with cheap chinese parts.
I built a +-30V supply form the "OP Amp Cookbook" back in early '80. It's right here powering my Dot Star featherwing right now (not much strain on it at 3.3v 😉). The Radio Shack power lamp has long since burned out and the switch failed in the "ON" position, but she's still cooking. These are great learning projects. Thanks for showing yours.
Nice! Thanks for sharing.
Subbed based on this video alone! i am trying to learn reverse engineering and component uses and this channel ticks all the boxes! i really like how you explain the different sections of the diagram in a brisk but informative way as i get easily distracted. Keep up the good work!
Awesome, thank you!
I used a couple of old 741's for U1 and U3, and a TL071 for U2, as that needs the offset adjustment ability. During original testing, I blew up Q4, which I thought was due to inadequate heat-sinking, but with hindsight, that may also have been a fake. I originally went for 10 turn pots, but all the ones I received from China were faulty, so I reverted back to single turn ones.
Good info, thanks.
Def go with the digital gauges. Unless of course you are going for a retro look.
I just like that digital ones are usually easier to see and some can be adjusted to correct limits.
fun stuff no matter how you build it.
Totally agree!
Great stuff, thanks. I love these little power supply kits, and have several. If you have UA741's (and several others), they will substitute fine for the TL081 , too. Since this "Original Hiland" circuit has been out since the '60's, there have been tons of mods to it that are out there, if you search. Did you calibrate the current with the trimmer, first? Maybe i missed that. Oh, and the pdf for construction and current calibration is available on Banggood, if you want it. I can't link to it, though, on here. These are great fun for the money and thanks for covering them. They tend to be often verbally abused, but can work great with decent components and some care.
Can you elaborate on what that trimmer is supposed to calibrate? I'm unable to see any difference in the output current or voltage at all whatsoever when I turn mine. If elaborating means copying a snippet from that PDF you mention, that's fine by me!
@@AnnaVannieuwenhuyse
Try putting in your search: " Instruction of Installation of 0-30V Stabilized Voltage Supply" and then scroll through the results until you come to a Banggood result, and that should be the pdf with everything. The reason for calibration is to zero your potentiometer correctly and so that the red led indicator comes on at the right time, showing constant current kicking in. Hope this helps.
@@englishrupe01 cheers!
No calibration done yet. I'll try that when I get some op-amps that are not doing crazy tings. Thanks for the additional info.
Great project, great video.
Thats a nice case, should look great when done.
The most common Op-Amp these days, for PSU's, is the LM 385. Even the cheap knock-offs are just as robust and accurate.
I see them, and use them, in both Linear and Switch Mode units.
Personally, I'm Analog Meters, but in this case we're Not eye-balling the guage every 2seconds.
The Toroidal transformer, what a shame. It was perfect for this project. I'd be inclined to order another from the same store.
Now the important question. Is that a Linear Power Supply, or "Linear Bench", as the title may imply. lol.
Happy trails.☺
Do you mean the LM358? IIRC the LM385 is a voltage reference. I have lots of LM358s but they will not work in this design. Yeah, shame about the transformer, but I don't really have the time to wait for another to come from China on this. The Traid one I'm getting is just a regular "E" core transformer, but it should do the job. Thanks for your comments!
You can never have too many power supplies. You’ll use both types of meters eventually. I like those blue cases with the white trim. I’m not sure the one you’re using is big enough for two analog meters, along with everything else.?
You may well be right. They are really small meters, but we'll have a look when they arrive.
Just in case anyone is interested, the TL081 op amp can be switched out with:
MC3371
LF351
TL061
TL071
OP42
UA741
amongst others. So, if you have stock, these are pin compatible. Fun to try, too.
I thought about the 741, but does it get close enough to the power rails for this application? I guess I could try.
@@uni-byte Yes, indeed. It works fine in mine.
@@englishrupe01 Just tried it and it does seem to work much better. Thanks for the info.
@@uni-byte Cool. Glad to hear it, and you are welcome.
I had one of these and had the same issues I think , it was a while so memeory is a little vague. When I tried it a few months later it had almost zero output, I did try replacing TL081 but that didn't fix it or atleast I couldn't check as one of them caught fire very quickly. I do have another kit somewhere I bought it when it was really cheep but never got around to building it.
Let me see if I can get teh bugs out of this one, then it might be worthwhile building up the 2nd one.
Just to be fair, this is a kit and it’s based on a Practical Electronics design that has been assimilated by others…just ensure that the transformers ac output when rectified doesn’t exceed the rated rail to rail voltage of generic op amps of 36volts…
It is. I got the kit for like $4 from AliExpress, but a bunch of changes were made. Did you see all 4 parts?
Add 1A diode from + output to + rail, cathode towards + rail. Will prevent Q4 destruction when output higher than rail voltage.
If I'm interpreting that correctly, placing a diode from Out+ to Supply+ is the same as placing a diode across Q4's Emitter to Collector, where it clamps thje emitter to collector voltage across Q4 (output transistor) to Out+ minus one diode drop? Which would be within the safe zone of of the emitter to base voltage, preventing the destruction. Current would flow to only a minimal degree, so this could be a small 1n400x rectifier diode or a small SBD.
Eager to hear if I've got this correct!
Good idea!
@@AnnaVannieuwenhuyse Yes you got it
Great idea....many thanks.
I think that I mentioned in the mail bag episode that these red board 30V/3A PSUs are (all) faulty. You have mentioned most of the known issues. Add bad traces from being copied over and over by different suppliers. I built three; all failed...
"It is never afraid of the fireworks!"
Are you saying the PCB is incorrect ? if so where please.
@@andymouse Yes, some YT builders have discovered trace errors. One builder bought three boards from different suppliers. Two had two different trace errors. His third board also failed. Due to fake op amps, as I recall. He was trying to find a way to identify sellers offering original kits. This was a recent review, but I forget what channel. If I come across it, I will post the details.
There are a lot of YT videos on folks trying to correct the myriad of problems with these kits. For these, add the term "upgrade" to the search title.
These kits have a very long history. I studied it out, about 10 years ago, when I was getting started. IIRC, the original design was an open post to a forum/blog/etc. It was just a prototype. The over-seas folks grabbed it up and went into production, without fully finishing the design. The under-rated/hot resistor that UB first pointed out is a known original problem that was not corrected and was carried into the rushed production. The remakers have never bothered to up its wattage. It has been down-hill, ever since, and with copies of copies, it seems to be getting worse. No guarantees on my memory. It is old and foggy.
I'm pretty sure that's the same kit as mine so I'll have to check my op amps. Do you have a link to the transformer you bought. I need a replacement so I can get the full 3 amps out of my power supply. Right now I can get about 1.5 amps max with the salvaged transformer I have in there.
If you do get a transformer, try and aim for under 24V AC. A toroidal transformer is therefor quite beneficial, as you can unwind some windings to drop the voltage if need be. This is just to save your TL081CP's from being cooked.
Alternatively, fix the issue with the positive supply voltage on the op amps.
I'll put a link to it in the description.
@@AnnaVannieuwenhuyse The total across the op-amps should be around 38V. A real TL081 should handle that okay.
@@uni-byte Thanks for the link I appreciate it.
Pat, before you go ahead and order that transformer watch some more of the videos on this. There are other problems. that you might want to address.
What do you mean by the primary is open? Broken? As in no continuity?
Yes.
Yep, no continuity. It might just be a rare case. I see lot's of people buy these toroids from AliExpress or Banggood and have good luck with them.
@@uni-byte I always try to get used if i can from yard sales or Ebay. I got so lucky with my biggest toroid. It's out of an old audio amp that was 2,000 watts from 220v, so i only get around 1200v from 120v (i imagine?). Anyway, it cost me 35 bucks shipped off Ebay. Amazing deal except i can barely lift the bloody thing...lol. Made a nice case for it, though.
@@englishrupe01 LOL!
Is this another cheap Chinese copy? I purchased one 2 years ago that had parts missing and was a pile of junk.
It is. No parts missing but the op-amps are NOT TL081s. We'll get it working just for the fun of it.
I've always been skeptical of these cheap DIY kits from China. Seems like an easy way to make a buck by shipping them out with counterfeit or faulty surplus components and then pass the buck to the hobbyist builder for a failed unit due to implied improper assembly -- especially since they don't include schematics or instructions.
I've also been looking at these boards and in some listings there's the option of buying a pre-assembled board for a couple bucks more. That's the only way I'd buy one, because then you have some refund recourse if it doesn't work... although they might still claim you incorrectly hooked up the external transformer or some other peripheral component.
Of course part of the fun of these is the build itself, so I'll be following your progress to see how it turns out before deciding if I want to give it a go!
It is fun to build things for sure. For me it's even more fun when they don't work quite right or can be upgraded.
@@uni-byte Exactly. To be honest, i find the challenge of troubleshooting the problems these can give most fun, too, although, now i tend to know them pretty well, i can figure them pretty quickly. I find it best to keep a supply of my own good op amps on hand, plus a few power transistors and the big shunt resistor. Electronics Repair School has upgraded his by paralleling two of the power resistors (sorry, i meant transistors) . I must have at least ten of the boards now and all the boards work fine apart from the obvious issue with fake op amps (plus some of my own stupidities). These boards are 3.55 bucks now with free shipping (over ten bucks) on AliEx, so i think expecting them to be perfect is a bit much.
that 1/4th watt resistor surely not capable for the job. replaces it with 3x 220E when building it few years ago. and they are still shipping this with 1/4th watt !
also used a 1/2 watt for the resistor next to it.
and i m not sure why the capacitor next to it popped after few minutes. just use safety goggles when testing with cheap chinese parts.
SO far I've had nothing pop on mine, but I did some mods as you can see in this series. I actually use it nearly every day for something or another.
I built one. Very disappointed in its operation
Seems to be a trend unfortunately.
@@uni-byte It would have been easier to use an LM723 and build around that.
@@dannyperry8070 it's a diy kit. that means, you need to do some diy mod to get the desired performance from it. 🤣
@@iceberg789 Yeah I know. I purchased one and I was very disappointed with its performance. Its in my junk circuit boards