Bart asked 2 years ago
I have a question about using a ESP 32 device in mt application.
The sensor I need to use runs on 12 volts DC. It contains a mechanical relay that provides the signal I need to use at 12 V. The contacts on the relay are isolated from the power to the sensor.
As I understand, the esp 32 needs no more than 3.3 V for power and as an input trigger.
Can I use a voltage regulator, attached to the power terminals of the sensor, to power the esp 32 and the common terminal of the relay to both power the esp 32 and provide the signal?
Do I need any capacitors or resistors in this circuit or would just the voltage regulator be enough?
Also, looking at Digikey’s site, what’s the difference between a shunt, linear or other voltage regulator? Which type should I use?
Does the input pin sink any current to ground? I mean, can I use a resistor to drop the signal from 12 v to 3.3V?
Rui Santos Staff answered 2 years ago
Hello Bart,
- Important: The ESP32 can be powered with 5V in the Vin pin or via the USB input. However, it does output in the output GPIOs a 3.3V signal to control the relay
In theory, you could drop the voltage from 12V to 5V just using a voltage regulator, but it will waste so much power and release too much heat (because they are inefficient). No, unfortunately you can’t drop the voltage using only resistors…
You could use a Step Down Buck Converter, here’s an example: