I would like to build a prototype circuit that is the equivalent of a digital potentiometer to control a 120VAC / 400mA load.
Purpose is to reduce the supply voltage for a 41W positive displacement pump so that the flow characteristics can be digitally controlled. The pump is essentially a spring-mass plunger driven by a solenoid at 60Hz. (I'm pretty sure there's an internal diode acting as a half wave rectifier).
The concept has been proven using a fixed resistor in series with the pump. Next, I would like to digitally control the value of the series resistor in order to vary the pump output.
I've already tried using a phase angle controller, but messing with the shape of the sine wave seems to confuse the pump once the delay approaches a half wave. This might yet turn out to be the best solution, but I'd like to try a digitally controlled resistor, too.
I've done some online searching, but haven't found anything that can handle the 120VAC and 400mA. Before trying to reinvent something, can someone point me in the right direction?
Thanks in advance.
Jim
Purpose is to reduce the supply voltage for a 41W positive displacement pump so that the flow characteristics can be digitally controlled. The pump is essentially a spring-mass plunger driven by a solenoid at 60Hz. (I'm pretty sure there's an internal diode acting as a half wave rectifier).
The concept has been proven using a fixed resistor in series with the pump. Next, I would like to digitally control the value of the series resistor in order to vary the pump output.
I've already tried using a phase angle controller, but messing with the shape of the sine wave seems to confuse the pump once the delay approaches a half wave. This might yet turn out to be the best solution, but I'd like to try a digitally controlled resistor, too.
I've done some online searching, but haven't found anything that can handle the 120VAC and 400mA. Before trying to reinvent something, can someone point me in the right direction?
Thanks in advance.
Jim