ESP32 Forum

I need to switch ON and OFF a latching solenoid valve by reversing polarity (ON in one direction and OFF by switching polarity of supply, ). For this I need H bridge chip with low voltage drop. I need to power it for only a few milli seconds (no continuous current or fancy motor speed control )
In face I can switch the valve ON and OFF using power from 3 V pin of ESP32 by manually switching the polarity. But to control it by software I need some H bridge.
My supply is either 3 V pin of ESP32 or directly by 3.7 V lipo battery.
I built H Bridge using four 2N2222 BJT transistors. The bridge works fine with LEDs but cannot operate valve due to voltage drop. For the same reason of voltage drop, I dropped the idea of using L298N or L293D motor drives.
Can someone please recommend some good H bridge chip for this purpose which can operate with 3 V and a few milli amp current without losing voltage?

Are you 100% sure you only need a few mA, and never more than that? In that case, you can even just use 2 GPIOs of the ESP32; just make sure to have good flyback protection. However, a BJT-based H-bridge, if built correctly, should also work. You said you used 2N2222 transistors, however, a proper H-bridge has both P- and N-based switches (BJTS or mosfets) (or some logic to bootstrap an all-N H-bridge), maybe your issue lies there?

If bjt voltage drop is the problem, why not use a mosfet h bridge (with p and n low threshold mosfets , e.g. BSS84 and BSS138 ) ? See https://circuitdigest.com/electronic-ci ... ing-mosfet for the schematic.

@Zeni241, what latching solenoid are you using that operates on 3V? What is the solenoid activating?

I have circuits for operating latching solenoids but these usually require much more than 3V to switch (typically 9V or greater).