Hi I'm looking for a USB controllable (or less ideally a serial interface of some other kind) solenoid controller that can switch up to 8 small (<1A) solenoid valves with hit and hold*.
The best I could find is the phidgets 16x solidstate relay which acts as a low side switch but lacks the flyback diodes since the driving voltage needs to be external. I've used this in the past but without diodes it can't freewheel when outputting PWM and so the performance is poor.
Obviously I could add the diodes myself but I have more money than time so ideally an industry focused solution would be best.
*: "hit and hold" is a solenoid driving technique that drives a solenoid at DC for long enough to actuate the plunger (usually a few hundred ms) then PWM's the driving current to reduce power consumption (and HEAT!) while still holding the plunger in place.