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Maintain voltage output...


Dec 18, 2010
Dec 18, 2010
I am working on a project that I want to simulate into a circuit.

This is the real thing:

To help you understand what is all about, this is an exhaust valve actuator from my Kawasaki Z750. The motor opens and closes a valve. This is the mechanical part. The electronic part is that this motor is connected through a rheostat to an input of the moto ECU. There is a feedback to the ECU that tells if the valve is working or not. If it is not working or stuck an error light lights up!

And this is the schematic:

At t=0 sec, there is no voltage to Motor_1 and Motor_2 we have 3.6 Volts to feedback wire...
When voltage applies to Motor_1 or Motor_2 then the motor turns the valve and the "needle" is moving up or down the resistance of 5kOhm of the rheostat.

Motor_1=12 Volts DC
Motor_2=0 Volts
Feedback=3.6 Volts DC after 0.4 sec (Capacitor is charging)

And when:
Motor_1=0 Volts
Motor_2=12 Volts DC
Feedback=0 Volts DC after 0.2 sec (Capacitor is discharging)

The other wires are just +5 Volts DC and Ground
Another thing in mind is that when the feedback reaches the desired voltage, ECU cuts out Motor_1 and Motor_2.

This is the circuit I have come out with:


As you can see I don't use the +5 Volts DC wire.
But in this circuit when Motor_1 and Motor_2 wires are 0 Volts, the capacitor discharges...
My problem is that I want to keep the feedback voltage, for as many time as the two inputs are 0 Volt.

How can I make it work?