# Gradually increase and decrease voltage on this circuit

I am using this circuit for a model lift up and down functionality. Vin is +12V. The output voltage is controlled by the 10K linear potentiometer that varies the final output from 3V to 12V. The DPDT controls the direction of the lift by reversing the polarity of the output voltage. The only problem is, when the pot is adjusted, the voltage drops or increases instantly giving the lift a jerk. Is there a way to smoothen the process so that the Voltage drop or increament is delayed over a few seconds? I have tried to increase the value of the output capacitor to 1000uf but it did not help.

I guess moving the potentiometer more slowly is too obvious?

Place a resistor between the wiper of the potentiometer and the 10 uF capacitor. 100k will give a 1 second time constant. For a still higher time constant I'd increase the capacitor rather than increasing the resistor.

• Did you decide this is the best answer in 10 seconds?? In general it is advised to wait some time, to give others a chance to give a (maybe better) answer. Aug 23 '15 at 17:18
• Oh, I don't know about that. Regarding why the pot cannot be always controlled, it is set at a certain speed for the lift to go up and down. When the switch is put off, the lift halts with a jerk. If the voltage gradually decreases then it can come to a stall slowly.
– Basu
Aug 23 '15 at 17:30
• Which capacitor, the one on the pot wipe?
– Basu
Aug 23 '15 at 17:31
• The one on the pot wipe. But that will smooth the effect of the pot (as you asked in your question), not the effect of the switch, as you seem to ask in the previous comment. Aug 23 '15 at 17:33
• For the effect of the switch, I tried to increase the output capacitor value, but it did not help.
– Basu
Aug 23 '15 at 17:35