DIY UPS for PI - Assistance

Came across this post.

Trying to recreate this but tweek it a bit.
The finished circuit outputs approx 4.5v due to the shottky diodes (I think).
From my limited knowledge, the SR340 diode drops the voltage by 0.5v
to reach a target of 5v, would it be simple enough to feed 5.5v into the circuit?

With the current setup, I seem to have burnt the resistors balancing the capacitors. would this be due to insufficient resistance or wattage rating?

Lastly, on the script component, can this be done with “gpiozero” ?
or should I be looking into something else?


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Hey Dominic,

That’ll depend on the ratings of the other components, and whether or not you’ll have a linear relationship between the input and ‘output’ voltages in this case. I’d guess that’ll be your wattage rating in this case, as the resistance will simply limit the current that’d able to pass across, but it’s hard to tell without the parts in front of me. You should be able to use the Gpiozero package to be able to simplify that script. However, in this case it may be best to write something custom to have a full understanding of what’s going on with it. All the best with your project!

Core Electronics | Support

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Thanks for the guidance.
Have completed this project. works quite well.

Hi Dominic
4,5V, 200ohm = 22.5mA
22.5mA, 100ohm = 2,25V = about 51mW each resistor.
Unless you are using very small resistors (0.1W) there is something very wrong.
Are they actually burnt or just getting a bit warm.
Are they 100ohm? If only 10ohm they would be dissipating about 500mW. Too much for a 1/4W resistor.
This would be my guess. They are 10 ohm instead of 100. Easy enough mistake, especially the 4 or 5 band types. Safer to measure.
Cheers Bob