# Proportional Valve Driver

I was trying to design a driver of a proportional valve. My driver has ±10VDC input and ±100mA output (Load: 200 ohm, 0.5 H, Series RL) I have two supplies which are 28±4VDC and -28±4VDC. I applied this circuit and simulated. I take ±100mA when i applied ±32VDC to opamps supplies however i took ±90mA for ±28VDC and ±75mA for ±24VDC. It was fixed to 100mA when i applied bigger supplies than ±32VDC. Also there is some problem about load, the output current should be independent from load resistor but values bigger than 200 ohm, the current was influenced. I have included the circuit.

I investigated some proportional valve models and i realised that they can give almost 3A. Do you know that how that circuits can give those currents? My circuit is limited at some values for some reasons but i couldn't find it.

This is a commercial circuit example for proportional valve: http://agsotomasyon.com.tr/content/ags-pv02-2-kanal-oransal-valf-kontrol-karti

• Mmm what about Ohm's law? You have 200Ω load and 100Ω shunt in series. What's the maximum current which can flow when powered by 30V? Commented Nov 29, 2016 at 10:13