Electronics
Some very interesting Raspberry Pi projects require some electronics work to get them to work properly.
My simplified electronics cheat sheet.
Top boards must face away from the Raspberry Pi. I don't like RPi hats because they block air flow to the CPU.
Solder on only one side of board; use the other side for the components
Wiring colors:
White = ground
Black = power
Yellow, Red and Blue = GPIO pins
Raspberry Pi GPIO pins have built in resistors - all GPIO pins REQUIRE diode or resistor
GPIO input should not exceed 3.3v. Use 1A, 3.3V zener diode to protect a GPIO pin from overload
RPi's GPIO pin -+- cathode of zener diode -- ground. The + is the input to the GPIO pin
Place a diode between GPIO output pin and circuit
Calculations:
Ohm's Law: V = I x R (voltage = current * resistance)
Use Ohm's Law to calculate everything
Resistors
in series
(2) R = (r1 x r2) / (r1 + r2)
(3 or more): R = r1 + r2 + r3
in parallel: R = 1 / ( 1/r1 + 1/r2 +1/r3)
Capacitors
in series
(2) C = (c1 x c2) / (c1 + c2)
(3 or more) C = 1 / ( 1/c1 + 1/c2 +1/c3)
in parallel
C = c1 + c2 + c3
Power = V x I = I**2 x R
Components:
Resistors (reduce amount of current) - non-directional
Diodes (prevent current flowing in wrong direction)
Capacitors
Transistors (emitter, base collector)
Wire: 20 or 22 gauge
Basic Circuits:
Voltage divider: GND -- r1 -- Vout -- r2 -- Vin
r1 / (r1+r2) x Vin = Vout