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I am considering this 5V regulated PS module. I have a coin acceptor that connects to a board. I am going to cut the coin acceptors 12V cable and put the -ve and +ve behind the regulated power supply below. Then use a USB cable to power the Pi.

Then if all goes well, I need to craft a way to register the coin acceptor pulse via the GPIO.

For now, is it okay to use the above power supply to power Raspberry Pi?

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    "5.0V+/-0.8V" maybe not enough/too much for RPi, that has much stricter voltage tolerance, I believe 5.0+/-0.2V.
    – lenik
    Jun 10, 2014 at 3:11
  • The USB standard is something like 5V +/- 0.25V. The Pi can certainly handle more at the upper end. Your dongle says 4.2V to 5.8V. The 5.8V would be fine, especially as you'll lose a bit going through the microUSB cable. The 4.2V would almost certainly be too low. See if you can find a dongle with a trim-pot so that you can manually set the output voltage.
    – joan
    Jun 10, 2014 at 8:03
  • A good thing to do would be check the voltage output with a voltmeter, so you can establish it before trying it on the Pi. I (accidentally) put 5.8V volts through my Pi (probably in the wrong place anyway), and it melted the writing on top of the SoC...
    – Wilf
    Jun 10, 2014 at 14:16
  • Related question: raspberrypi.stackexchange.com/questions/11917/…
    – Gerben
    Jun 10, 2014 at 15:46
  • I don't want to take risks, just want a transformer/powersupply that can step down 12v to 5v +/- 0.25v and provision a wifi device over usb. here is another one with better specs, but it is a transformer dx.com/p/…
    – Syler
    Jun 10, 2014 at 16:11

4 Answers 4

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Yes, that will work just fine.

It's essentially the same as an UBEC and I have seen people reported that they are running their Pis off 12 volt from their PC Power Supply or other 12V adapters, for months without any problem.

The one you have is very good. Just remember some of the older Pis have 1A polyfuses on the power USB port. So, if you plug in a wi-fi dongle for example it will reset the Pi.

You can wire it to the GPIO Pins but beware, these DC-DC do not protect from short circuits or reverse polarity on the OUTPUT side! Put a fuse on the +5 volt, it's worth the hassle. You don't want to fry your Pi.

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If you use a 5v regulator to drop the 12v you have down to the 5v you need, your 5v regulator will be dropping 7v across itself. Even at small currents, the 5v regulator will be trying to get rid of significant heat. If something needs 250mA at 5v, say, the 5v regulator will be generating 0.25 x 7 Watts, or just under 2 Watts. So, if you go this route - which is fine - don't forget to make sure the regulator can get rid of its heat into a heat sink, and that the heatsink can get rid of the heat its receiving, too. Many folk forget that last bit! ("I've put a heatsink on it." Sure, but the heatsink is cooking hot!') Most modern regulators will 'shut down' if they get too hot, and they do this progressively - which means they supply peculiar voltages as they shut down. This can be extremely puzzling, as (usually) the electronics being supplied does odd things! By the time you take a look, the regulator has recovered (cooled down a bit), and voltages look ok ... for a while!

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    Hello and welcome to RaspberryPi SE!
    – Ghanima ♦
    Apr 2, 2015 at 21:08
  • A voltage regulator in the sense of the OP is by no means limited to linear regulators that show the problems with thermal load you describe. Switching regulators are pretty common these days - and the linked product of the OP most likely is switching type given its power ratings and size, although the description does not offer much information.
    – Ghanima ♦
    Apr 2, 2015 at 21:08
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If you read reviews for this product, people report stable 5.1V supply, wich should work perfectly for Pi, just make sure you double check under load with Voltmeter in your operational range of input voltages/temperatures.

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It should be fine with the following considerations:

  • Try to ensure the regulator is a switching regulator, this will ensure that you don't generate excessive heat while regulating the 12V input;
  • Some voltage regulators have a tendency over time, especially cheap ones to lose their ability to regulate effectively and the output voltage can increase beyond what your device expects and could cause issues;
  • Please do not wire it to the GPIO pin to feed power to the PI. Dissect an old USB cable, attach the red and black wires to the regulator, solder and tape or heat shrink these connections. Connect the USB end to the Pi. This ensures you use the circuit protection that you paid for with the Pi;
  • Check the voltage coming out of the regulator with a meter before you connect it to the Pi for the first time.
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