Testbench Power Supply Unit (PSU) for Rpi

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I’ve owned Pi’s since the first generation and have had various test rigs made from what I had to hand including stepping the voltage down from 12v and various bits of lego holding the components in space. Whilst good fun it is not the safest approach for humans, animals and the components.

I have purchased a Pi 4 with official touchscreen which will become an Android Auto car PC (nicknamed Otto). Otto will eventually live in a custom made enclosure in the vehicle but while he is being configured I would like him to be cosseted on a nice test bench with a 240v AC supply going to the 12v DC to 5v DC 3amps that will be the input for all Otto’s power needs.

What recommendations would you make about the 240v to 12v power supply and avoiding static so I don’t end up baking my pi? Should I bear anything else in mind (I am neither an electrician nor an electrical engineer) such as a capacators to smooth his power supply and cut out alternator noise?

  • 1
    I use a laptop supply which conveniently produces 12V. To generate 5V from the 12V I use a UBEC. Not sure of the relevance of the Pi to this question. Probably the wrong site. – joan Nov 13 at 17:41
  • 1
    @Mike Poole, Ah, let me see. I would suggest an AC220/240V to DC12V 5A PSU, something like this: imgur.com/gallery/G3gc5T9 – tlfong01 Nov 14 at 3:40    
  • @tlfong01 many thanks for that. I will get one similar to that. Do you think using a capacitor would be a worthwhile or does the Pi generally not mind if the supply is a little noisy? – Mike Poole Nov 14 at 3:46
  • @Mike Poole, By pass capacitors are usually not necessary, unless in noisy industrial environments. You might like to read my answer to the following question about by pass capacitors: raspberrypi.stackexchange.com/questions/98116/…. – tlfong01 Nov 14 at 3:54   
  • And in the old days, car engines generate a lot of “sparks” related back EMF, EMI inside the car compartment, but there were no electronic things inside the car, so no problem at all. But now if there are noise interferening the auto pilot guy, who might pilot you into wrong direction, hit a big white or blue wall etc. So to play safe, noise filtering is a good idea. But let me see if your Android Auot/Otto is strong enough to shield off noise. / to continue, … – tlfong01 Nov 14 at 4:08   
  • (1) Android Auto on Raspberry Pi: OpenAuto – Lucy Hattersley, MagPi 2018 magpi.raspberrypi.org/articles/android-auto-openauto (2) Add Android Auto to Your Car with a Raspberry Pi and Touchscreen – Cameron Coward 2017 hackster.io/news/… (3) Crankshaft Android Auto for Raspberry Pi driving demo – 2018 youtube.com/… – tlfong01 Nov 14 at 4:09   
  • @tlfong01 many thanks for that. From what you’ve said I’m swaying towards adding a capacitor because of the alternator. – Mike Poole Nov 14 at 4:28
  • @Mike Poole, I also have a small footprint dual purpose 200VAC/12VDC 1A and Lipo 11.1VDC power bank, so I can carry it to my rooftop garden for field testing: (1) imgur.com/gallery/fhgnRXG. Other ideas you might also be interested: (2) raspberrypi.stackexchange.com/questions/102115/…. Cheers. – tlfong01 Nov 16 at 3:09   
  • @tlfong01 thanks for that too. I am getting rather into this and your comments are helping a lot. As a separate project I have been building a 12v leisure battery box (codename = Zeus) that could also power Otto. I have also ordered a 5v 3.1amp electrical socket faceplate. Can you forsee an issues about me using that to power Otto? I think I would need a very good USB cable if I were to do that so I’ll open a separate question about that as I am sure the answers would be of interest to others. – Mike Poole Nov 16 at 11:07

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