I have built an H bridge to control a coil but I've got issues ...
I built my H bridge with 4 darlington transistor : Tip122 (datasheet : https://www.onsemi.com/pub/Collateral/TIP120-D.PDF) and I control it with an arduino MEGA.
I made a program that sends a square wave signal of 5V through the pin 7 & 6, and it works when I observe it on an oscilloscope. However I can't have more than 0.3V at the level of the coil. I need roughly 3-4V and 3A for my coil(the resistance of my coil is 1.4Ω).
I put 1K resistor and the TIP122 have a gain of 1000 so it should be satured.
I have try everything but it still not work... I read on internet that with this type of circuit I will not have more 4 V at the level of the coil but I only have 0.3V, wich is clearly not suffisant.