How to control a relay with an Input Voltage

154

02:56:31

Input Voltage: purple

published 10 years ago

imtyrone

10 years ago

Thats pretty neat

lenzrulz

10 years ago

You need to protect the transistor from excessive voltage spikes from the relay coil by using a diode.

emanuele6

10 years ago

Thanks, lenzrulz

thebugger

10 years ago

The diode goes from Vcc to the collector in reverse junction

thebugger

10 years ago

The spike is still there at 11kV for 3uS

lenzrulz

10 years ago

Replace the diode with a Zener diode, set the Zener diode to 13V (this will significantly reduce the massive voltage spike plaguing the circuit) and then adjust the relays must operate voltage to 2V and the must release voltage to 2V. 👉PS: You will notice a slight relay activation and deactivation delay👈

thebugger

10 years ago

No, don't do that, it'll burn out the zener. Just add a diode in antiparallel to the relay coil (reverse junction) cathode to Vcc and anode to collector. This way when you stop the supply for the coil it'll discharge on itself through the diode.

add comment in editor

EveryCircuit is an easy to use, highly interactive circuit simulator and schematic capture tool. Real-time circuit simulation, interactivity, and dynamic visualization make it a must have application for professionals and academia. EveryCircuit user community has collaboratively created the largest searchable library of circuit designs. EveryCircuit app runs online in popular browsers and on mobile phones and tablets, enabling you to capture design ideas and learn electronics on the go.