I want to control multiple (15 - 20) solenoids by using a common single variable resistor. For example solenoid 1 will energize if control voltage is between 1 and 1.25 volts only. Solenoid 2 will energize if control voltage is between 1.5 and 1.75 volts only, etc. Solenoids will be parallel off a single 12 -24 volt line, control circuitry will be parallel off a single 0 - 12 volt line.