Simple AC to DC power Supply for Big Red Dome Push Button.

The Problem:

I recently had a customer ask me to suggest a product similar to Big Red Dome Push Button but to use with a 24 VAC supply.

Big Red Dome Push Button

The Solution:

I suggested that he make a simple bridge Circuit using 4 rectifier diodes a resistor a cap and a 12 V zener.

The Diodes are 1N4001 the Resistor is a 330Ohm 1/2 Watt and the zener is a 12V 1/2 Watt, the cap is  100uF 60V.

This circuit current is limited by the 330 resistor to ~36ma if you require more current drop the resistance and switch out the zener to a 12V 1W or larger.

To get the maximum current for the circuit we take the watt rating of the zener over voltage so at 1W / 12V = 83ma.

Using Ohms Law we calculate the required value of the resistor as the voltage drop over current = 24-12/83ma = 144 Ohms.

Parts List for this project:

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