NE555 Door Solenoid Control

377

04:13:22

Final version of my NE555 timer door control (circuit # 4503779493543936). Switching the solenoids is now done by MOSFETs (IRFZ24N or IRLZ24N). The rest of the circuit hasn’t changed much at all.

Solenoids are 6VDC types with a 100% duty cycle operated in overdrive on 12VDC for increased power from smaller and cheaper solenoids. For the short actuation times this is not a problem at all and also lies well within with the manufacturer’s maximum ratings.

Edit: Added LEDs for better visualization and forgotten diode at second timer; the simulation doesn’t require it but IRL it’s necessary. There was also a weird glitch with the MOSFET for the second solenoid opening for milliseconds on power-up of the second timer. It doesn’t happen with the LED and resistor in parallel to the solenoid, a regular diode and 10k resistor will also suppress the transient. I think it’s a simulation issue; I have used the second timer design in the past for other purposes, like turning on speaker outputs with a delay, and have never seen this glitch IRL.

Simulation runs at half speed.

published 3 years ago

CTriano

3 years ago

If I wanted to increase/decrease the time of actuation between both relays, then what component value would I alter?

Zapotron

3 years ago

Hi, you can play around with the 33k resistor and 47u capacitor at the left NE555 for the total on-time. Iincreasing the value of one or both gives a longer interval. IRL the NE555 can handle intervals up to hours but the simulator fails at very high values for capacitor or resistor. For a longer delay between the relays you have to likewise increase the values of the 10u capacitor and the 47k resistor at the right NE555. Note that the circuit will eventually turn off both relays at the same time once the timer on the left reaches the end of its set interval.

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