I have a RaspberryPi-controlled irrigation sprinkler system that I am working on. I would like the RaspberryPi and the Solenoid Valve (when the Solid State Relay is closed) to pull power from the same source. I would like to verify I have calculated the correct resistance in the diagram that results in a 5V supply to the RaspberryPi (and that all other connections look ok).
- The Pi and SSR are in parallel thus both subject to the same 120VAC
- A Pi normally draws 2.5A using 5V resulting in an effective resistance of 2.04 Ohms (
- Treating the Pi loop as a series circuit, I can get the current across the resistor
- I must then find the voltage drop across the resistor
Rthat results in 5V supplied to the Pi:
5V=120-dV_Rwhich is the same as
- I know how have:
Solving these equations results in
Did I do all of this correctly?
If the 120VAC power is coming through 12-14AWG wire, what is the best way to "connect" that to the resistor that meets the Pi power supply? That is, on paper these connections look fine to me but in practice, how would you do this?