Need higher current power source

[vibnwis]

Hi there,

Would very appreciate some advise, please! My electronic knowledge is limited.

I have two 3.3V 0.15A fans to connect to GPIOs of ESP32 WROOM. What would be the best options for getting up to the current specifications? I am thinking to connect to another USB port and step down to 3.3V, options are:
1) connect that to ESP32 WROOM Vin. Would it work?
2) connect to fan Vin with extra control circuit. Is there any that have built-in control circuit?

Hear from you soon.

Thank you
Lim

[kolban]

Howdy Lim,
My electronics skills are poor but if I had that puzzle, here is how I'd approach it.

If the fan draws 150ma, that is far more than you can source from a GPIO pin. I believe the limit is ~60ma. To solve that problem, I'd use a simple transistor. Connect the base of the transistor through a current limiting resistor to the GPIO. When the signal goes high, a small current will then flow out from the GPIO through the base of the transistor which will be amplified to produce a far greater current between the collector/emitter and the fan. Basically, using the transistor as a switch.

If the fan is rated at 3.3V then you should be able to source the voltage/current from the same source as your ESP32. If you want to isolate the fan from the ESP32, consider an opto-isolator which will completely electrically decouple the two.

[vibnwis]

Howdy Kolban,

Very well explained. Thank you so much.

I worked on something similar, instead building from comonents, I've bought a "Micro DC Motor 3.3v 5v Driver Board Module Controller" from Ebay just cost about USD2. to eliminate messy wiring and soldering etc. It is neater with modules, and reuseable as well.

Thank you sir.

Lim

[permal]

Remember that the fans probably draw more than their rated current during start up, so dimension your electronics for that.