Build a Small Dual Rail Linear Bench Power Supply.

[@GapRecordingsNamibia]

It is refreshing to find someone on youtube who has actually completed a linear PSU albeit a small one, Congrats and well done!

[@TheStuffMade]

Thanks, yeah you can't beat a linear power supply in low noise and general performance especially if you're working with analog circuits. Switch mode supplies are good when you need a lot of power. Cheers, Jake

[@GapRecordingsNamibia]

@@TheStuffMade WOW! You replied? You are the first one on KZbin that has replied to a comment I've left on their channel regarding ACTUAL BULT PSU,s, what I mean by that is not taking an already made solution and modifying it to suit your needs but actually building it from scratch. I am currently building one for myself, purely because of price and my location, stuff out here costs 10 times what it does in other countries so DIY it is the only way for us I'm afraid. Not that I'll ever get all the accuracy of a bought supply but hey ho, one has to make certain trade offs given ones skills. Which mine aren't the best but I do try. Regards Charles from Namibia

[@carlgradolph9676]

Excellent work from start to finish. I have never built a power supply before, but with the help of this video I think I'm ready to try. Thanks for taking the time to make and share this video. One more subscriber added!

[@karlmartell9279]

I'm very impressed how well build this device is! Very well done!

[@klave8511]

Thanks for this video. I agree with the choice of a ic regulator, known specs known overloading performance. I know it costs more but the work is much less so very much worthwhile, probably cost less when all is considered. I don’t recall the lid but don’t see the venting for heat dissipation for those heat sinks, a small fan and airflow over the heat sink would be very effective. They are huge so maybe not a problem, the 317/337 are designed to shutdown when overheating. I didn’t know about the clear paint over paper, I will use that in future! I like an indicator for overcurrent, the meters are nice, analog is definitely a better choice for a multimeter. I recently made a linear power supply, not too different to yours and I realized that I can’t remember the last time I needed a negative power supply. So many op amps are rail to rail and work off such low voltages that I never need the negative rail. Admittedly I don’t really do audio work, that would likely need the negative rail more often. I also rarely use my switching supply, the noise depends on the load and I don’t want to introduce unknown noise. Even the radiated noise is a problem never mind the noise conducted in the wiring.

[@TheStuffMade]

Thanks, It's been some time since I built this little power supply and I can say it's served me really well without any problems. Using standard regulators really does simplify everything and avoids any nasty surprises. There is about 10 mm spacing between the heatsinks and the bottom of the casing, so even the vents are not perfectly aligned with the heatsinks they still work fine to draw cold air in at the bottom and vent it out at the top. The only thing I wish I had added is a power indicator led or perhaps some backlights in the meters, just to easily indicate that it's switched on, but it's not critical and something I can always add at any time. I've done another video where I put it through various tests and compare with a couple of other power supplies and it performed very well. Cheers, Jake

[@boonedockjourneyman7979]

Great stuff. Thank you. You are paying a serious price by using the LM series “regulators” rather than discrete components. It has been interesting watching the art of transistor based PSUs die over the last 40 years.

[@TheStuffMade]

Thanks, agree, there is both a downside and an upside to using the good old LM317/337, they do ensure simplicity in design and documented reasonable performance but of course they also present some serious limitations. I do however believe the linear PSU still belongs on every bench side by side with the high power (but noisy) switch mode alternatives.

[@BeetleJuice1980]

excellent built! can we use a 7805 as IC3 and a 7905 as IC8? what happens if we remove the lm334, i cant understand how it works. could we use some simple diodes (in combination with the +/-5v rail)for that "more negative/positive" voltage needed to the end of the CC pots? thank you

[@fursino]

I did build the same following your schematics. I had a problem with the negative supply that in particular was not negative keeping the potential difference vout(neg)-gnd= 2.33V. I did remove the lm334 on the negative side and now is regulating down to zero. Current regulations needs to be tested.

[@TheStuffMade]

Hello, that sounds strange, it works fine in my build and you can see in the schematic it's correct. Did you use the circuit board layout I provided or just some perf board? Maybe a wrong connection of the LM334 on the negative side? I recommend you add the LM334 again and make sure it's connected like the schematic shows, also make sure the LM334 isn't faulty. Cheers, Jake

[@fursino]

@TheStuffMade yes, I did follow you schematic, and the more I look, the more I can't see where the error lies. It must be a wrong connection. I did create the schematic on easyEDA and have the pcb delivered. I will let pass sometime before looking again. Anyway, it is a great experience to learn. Thanks a lot.

[@albertvalientecasas3553]

Very nice power supply design.

[@TheStuffMade]

Thanks!

[@RepairRadioLab]

Great video. How the over current protection works, there seems no relay..

[@TheStuffMade]

It used to be common to have overcurrent protection with a relay but in more advanced designs you will have current limiting, as in you set the current limit to e.g. 100mA and then the power supply will never deliver more than 100mA. That is how this power supply works, it's got two modes of operation, either Constant Voltage or Constant Current and it will automatically switch between the two modes depending on the set current and the load. Hope it makes sense. I have another video doing some power supply testing, it might help illustrate how these power supplies operate (kzbin.info/www/bejne/iJW3XquNeJmbas0) Cheers, Jake

[@RepairRadioLab]

@@TheStuffMade thanks for explaining, I have decided to build a bench power supply according to your design.

[@RepairRadioLab]

is it possible to add a led as over current indication? this would complete the design as the best. otherwise i have to use comparator instead of lm334 current sensor.

[@TheStuffMade]

Build a small low noise linear dual rail bench power supply, download details in description.

[@EngineeringVignettes]

Looking good. I have made more than one power supply in my past :) I guess you could put an earth terminal on the back panel... The 2 main filter caps are a bit in the way for 2 of the screws on the TO-220 parts... moving them out of the way for a screwdriver could be a future improvement... Are you going to add a +/- balance trimpot to get both outputs aligned? Have a good new year now, thanks for your contributions in 2019, especially the audio analyzer software... good stuff. Cheers,

[@TheStuffMade]

Thank you, wish you a happy new year as well. I decided to build this little bench supply because my large dual output bench supply is so large I don't really have space for it on my bench anymore and 99% of the time I don't need much current. Well spotted that it's hard to screw in the heatsink for the first two regulators, impressive, I didn't even think of that when I designed the board, but it was the reason I went with hex screws instead of regular phillips screws.

[@EngineeringVignettes]

@@TheStuffMade - Using allen (hex) head screw was a good idea. I have a personal distaste for phillips head screws in audio equipment, when one cannot get a good angle on the head to loosen it; that goes back to my technician days... cheers,

[@adrianm2782]

Beautiful work. Thanks for sharing

[@TheStuffMade]

Thanks

[@tecnisdaimondm.g9321]

Excelente 👌

[@amoontube]

Thanks for a really useful video. Can the pcb's be obtained anywhere? thankyou

[@amoontube]

uploaded gerber to pcbway - 5 on the way

[@BeetleJuice1980]

I am building your circuit and I have a question: c3/c7 film capacitor, you mean mkt or polyester? And c4/5/8/10 are ceramic caps? Thank you!

[@TheStuffMade]

Both regular polyester and MKT will work for c3 and c7. The 100nF are all ceramic, I use multilayer, but the disc type will work as well. Cheers, Jake

[@BeetleJuice1980]

@TheStuffMade Thank you, I am ordering the caps from mouser right now hope I don't do a mistake.

[@BeetleJuice1980]

@TheStuffMade c1/c6 is 2mm pitch, c3/c7 5mm pitch, 100nf are 5mm pitch if I measured correctly.

[@GapRecordingsNamibia]

Hi Jake, Hope you are well? I have a question about your voltage config please if I may ask... Why do you have R13 across your 10K pot? how does this change the resistance, is it now a 15K pot? The same on the negative side? Sorry for bugging, but would like to understand why it is being done. Thank you very much... Have a great day!

[@TheStuffMade]

Hi, actually it changes the potentiometer to around 6.7k (1/R = 1/10k + 1/20k) which is not a standard value and without the 20k across the pot you will not get full use of the potentiometer travel. Cheers, Jake

[@GapRecordingsNamibia]

@@TheStuffMade Thank you Jake, Understood.

[@alexstone691]

What current range would you get without LM334?

[@TheStuffMade]

Hi Alex, without the LM334 you might as well remove the whole current regulation section as it wouldn't work. Cheers, Jake

[@alexstone691]

@@TheStuffMade Thanks a lot for the reply

[@anurasenarathna1703]

Great