Hello everyone,
I would like to use the 6V input I have for my motor to also power the Photon to avoid having 2 power supplies. What is the best way to drop 1V? I thought about using a voltage divider but I read that a Zener diode might also do the work. This is all new to me and I don’t want to destroy my Photon…
Thank you a lot for your help!
Use a step down buck to 5V
Thanks @1bit!
I looked into the forum for a step down buck and found here Photon Power Supply Idea that I might need to add caps to avoid damaging the Photon.
After looking on adafruits, I was considering buying this https://www.adafruit.com/products/1385?gclid=CjwKEAiAj7TCBRCp2Z22ue-zrj4SJACG7SBEEI3fYRae2EHf-hc9C3C8gS1-qp8sRaVm1s7C40g7JRoCdVHw_wcB
Do you think I would still need to add caps?
@Rno Here is a Buck + Boost 5v converter that will supply even if the 6v input drops lower.
Remember usually a buck converter needs the input voltage to be at least 1v higher than the output for proper operation. So if your input could sag below 6v you have to be careful if you need a steady 5v output.
Oh thanks @RWB!
I think the 6v should be steady as it comes from a wall power supply.
The 6V is also powering a motor. If I put everything in parallel the 6v should be steady for the Photon, right?
Motors are notorious for doing bad things to their power supplies (large ± voltage spikes). You can buffer these with larger capacitors and use a nice buck+boost to ensure you are getting 5V all the time.
It’s hard to tell really. Some power supplies supply a steady voltage and some do not. The wiring from the power supply to the device could also cause voltage drop due to losses in the wiring.
The power supply will need to be able to supply enough current to power the particle device under max load along with the motors max load without dropping the 5v output voltage.
Folks, the easiest way to drop the voltage is using good old diodes like a 1N4001. You can have one or mode diode in series and each will drop 0.7 volts. Or, use a linear LDO regulator to keep things simple.
Since I fly model aircraft, I have used UBEC modules plenty of times. They take from 6V up to 23V, and keep a rock solid 5V at a decent amperage, so you can power practically anything else too. Mind you, if I didn’t have the UBEC’s laying around, I would have done exactly as @peekay123 suggested and added a few cheap diodes in series with the positive line until the multimeter reads 5V(ish).
Actually the photon CAN take up to 6.5V input MAX…a poly fuse would drop that by about 0.500V anyway so why not NOT kill any birds at all the photon has a MAX input rating …use a polyfuse. 500mA hold,1A trip SMD. and let the photon regulator give you the 3.3V
2920L050DR
I only suggested the BUCK because there may be other things you need to power besides the photon…like horns and lights BEEP BEEP…you could use a fuse anyway probably.from the sound of it. 
JOPO
Thank you a lot everyone for helping, I’m really learning a lot here.
I still don’t know exactly which of all the solutions I should use. All seem to work pretty well, just need to pick one and test, right? 
@1bit, @Rno, the 6.5V rating is an ABSOLUTE MAX rating and should not be used as an operating value. The recommended input voltage is 3.6v to 5.5v. Furthermore, the challenge with using a fuse is that it is a current protection device requiring a tripping delay which is typically in the order of seconds. The Photon may be damaged before the fuse trips. The most common failure mode I have seen with the Photon regulator is self-destructive feedback caused by poor USB power supplies or long wires causing inductive “ringing”. This was addressed in another topic.
Do consider your power requirements as a whole, including Photon and all peripheral devices. Your “whole system” requirements should dictate the power supply design you need.
I suppose he could add a 6.2 V Zener shunt to protect the photon after a fuse. but a good supply is a must.
1N5341B