Electronics > Projects, Designs, and Technical Stuff
Revive old power supply project or start from scratch
Ford-Prefect:
Hi Folks,
I am new to this forum and came here since I recently watched eevblog on youtube over and over.
The reason for this thread is that I stumbled over the power supply series of Dave and that reminded me of an old small project that became something like an ugly sleeping beauty. I started with electronics some years ago when as a student I helped to set up an after school club for pupils to solder small circuits like blinking led stuff, buzzers, etching PCBs etc. Back than I had the idea that a bench power supply for at home would be nice. I had a rough plan and shopped some parts but then finishing studying became more important and in the end I forget pretty much about it and didn't do a lot in soldering for a long time. But now I am fixed on again and also want to dig deeper and start with micro controllers and stuff. So a power supply would be handy and this brings me right back to the topic.
The Idea back then was quite simple. It would have been a symmetrical power supply with different fixed voltages and an analog ampere meter for each channel.
I got two of these https://www.reichelt.de/schaltnetzteil-open-frame-5-24-v-1-5-a-sp-1500-p57778.html
and two similar to these https://www.luedeke-elektronic.de/Drehspuleninstrument-Amperemeter-0-1A-DC-No-60.html.
I planned to connect the ground of one to the positive rail of the other over a switch to select symmetrical output or seperated output and use some turning switch instead of the setting jumper.
Since it's output shouldn't exceed 1.5A I had planned to put some thermal fuses on the output.
So I could just do it right now but actually I think it's not really a good device. I assume a voltage and current regulated device would be more handy and a bit safer in case a test goes wrong. Also I don't know if I really need symmetrical output. I think it could be handy in case one plays around with opamps. But I also heard that often ground is used instead of a negative voltage. When I saw the video series I thought maybe it could be a good Idea to just use one of this power supplies and set it to a fixed voltage and use it as an dc input for a voltage and current controlled power supply with digital display etc. so doing something similar as Daves supply but not with batteries and not with serial control etc. And maybe with higher voltages.
It's often said that this kind of stuff is a good entry project. However, although I could roughly follow Daves design I think I couldn't come up with something like this. So a design would be more or a less a combination of copying and varying solutions of others.
Does anybody have some advice for a novice where to start?
tkamiya:
I don't know which video or Dave's supply you are talking about. But if you want to do it right, power supply is a very deep and difficult subject. Noise, ripple, temperature coefficient, transient, etc, etc, etc.
On the other hand, there are many easy kits available that mostly use 3 terminal regulators. For many hobby projects, those will do just fine.
If you don't mind old and heavy, HP's variable power supply 0 - 40V 1.5A dual channel types are available for 20 dollars or so, if you can find them locally. I have a stack of them but shipping would be prohibitive. I don't know how old is old, but is there something you need improvement? Is this for fun? Otherwise, usable ones are available cheap on Amazon.....
Ford-Prefect:
Hi tkamiya,
I was referring to this project of Dave https://www.eevblog.com/projects/usupply/. Seems he stopped it at one point. Maybe that should make me thinking.
This is all for hobby and entertainment. I really like programming and technical stuff. It's always like some kind of riddle. This supply units I already have, I assume they are not bad and they are still sold too. But back then doing stuff for this after school project this was all 9V based analog circuit stuff. That made fun but thinking of some private projects for the future it's more about micro controllers and mixed signal. And there something in the 3V range, being regulated not in really coarse steps together with current limitation, might be more handy.
nemail2:
--- Quote from: Ford-Prefect on May 26, 2019, 07:03:12 am ---Seems he stopped it at one point. Maybe that should make me thinking.
--- End quote ---
Dave is working on it, he mentioned in some of his last videos that the µSupply IS happening. He seems to have progressed quite far already.
He is doing it behind curtains because the last project went kinda wrong because everyone was suggesting and criticising things and he tried to implement everything and listen to everyone and so eventually it died of features I guess.
I guess the µSupply will be Daves "next huge product" after the µCurrent and the EEVBlog multimeter. I hope it will be open source.
In the meanwhile you are welcome to take a look at my supply which has been kind of inspired by Daves work:
https://github.com/mamama1/LabPSU_Darlington
I guess my project is too huge to simply rebuild it at home but maybe you can gather some ideas from it. In the end, that's what open source hardware is for.
james_s:
Power supplies can be as simple or as complex as you like, you don't always need something fancy. For many years I relied on simple power supplies I built myself, many times I've just used surplus wall warts. Features like variable voltage and current limiting are nice to have but not absolutely necessary for many things.
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