3.3V GPIO to relay

331

07:33:24

Used to switch heavier loads from an ESP32

published 5 years ago

wyoelk

5 years ago

What is the purpose of the 10k resistor and the diode?

ElectronVolt101

5 years ago

good question ! i wonder why too !?

Robert_Kidd

5 years ago

The 10k is a pull down so transistor base is effectively grounded when the switch is open. The diode protects the transistor from back emf from the coil.

Robert_Kidd

5 years ago

I’d rather see the pull down at 100k. I’m not sure why a 4V operating relay has been chosen. The transistor is dropping 8V when turned on. I’d go for a 12V relay.

K0NRAD

1 year ago

Where does the delay come from when the switch is opened or closed?

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