ESP32 Forum

I tried to drive a relay module with heltec esp32 v2 board but it wouldn't turn on the green led. I tried connecting the vcc of the relay to the 3.3 pin on the board and also tried the 5v. The voktage supplied to the board is about 6v. If i connect the vcc of the relay to 5v of esp32 then the green light is always on even if the in pin of the module receives high or low signal from the esp32. When i connect the vcc of the relay to 3.3v then the relay is not turned on and neither the red led or tge green led is turned on. This is so confusing.

Please note thst i am supplying an ecternal 12v power to esp and using a buck convertor to to step down to around 6.3v because 5v exactly was not enough to turn on tge esp32. Very wierd!!

I measured the voltage at everywhere in the circuit and made sure it is tge correct voltage. Current is also ok.

Please note t am not a hardware guy but i am a full stack web developer who is interested in automating some of my daily work.

Thanks a lot in advance for any help or hint.

> When i connect the vcc of the relay to 3.3v then the relay is not turned on and neither the red led or tge green led is turned on.

Well, there's your likely problem. The ESP32 only can output up to 3.3V on its GPIOs, and presumably your relay needs 5V minimum.

ESP_Sprite wrote: ↑

Thu Nov 19, 2020 9:21 am

> When i connect the vcc of the relay to 3.3v then the relay is not turned on and neither the red led or tge green led is turned on.

Well, there's your likely problem. The ESP32 only can output up to 3.3V on its GPIOs, and presumably your relay needs 5V minimum.

Dear, my relay supports both 3v and 5v. This is exactly the relay i am using:

https://images.app.goo.gl/AbbV5JEX9VDbi8Y2A