I have an application where I want to use an aftermarket car door lock solenoid as a cheap linear actuator (because it’s basically what it is). It will run off 9-12V and be outside. It needs to be activated with an RF remote switch.
So these are two wire devices. Power it with a certain polarity and it extends. Reverse the polarity and it contracts.
What I need it to do specifically is to extend fully when activated by the RF switch, then hold for a set time 10-15secs by stopping power to the solenoid, then reverse polarity and fully retract, then switch off again. I’d prefer to just use off-the-shelf stuff rather than go down the path of coding a Wemos D1 or a NodeMCU but will if I have to. Coding is not my strong point.
Interesting… I have an extra door lock actuator here also. They are pretty wimpy in terms of how much force they can exert; but still could be made to do something useful. I’m thinking they only have like 6-8 oz of force.
Anyhow, you could start with something like this:
It would get you pretty close. But to add the latching, then reversal, you would need something more involved. I’m not sure if someone else in the community has ideas. You could pick up a timer relay; and use it to activate a DPDT relay. That would do it.
This relay triggered by the RF kit I think would have you going.
Yeah they aren’t very strong but the ones I have are strong enough for what I want to do with them. They are also really inexpensive compared with even a small linear actuator.
Something that triggers 2 relays, one for power, one for direction. Take advantage of the Normally Open/Normally closed pins for the direction, then use the second relay to power it long enough to perform that action.
Those dual relay 433Mhz RF modules are great. I drive mine with a Sonoff RF transmitter.
They are “dumb” devices but you can make them smart through automation software. I use Home Assistant but the Sonoff eweLink app with the RF transmitter could potentially also do this.
“Learn” one relay as Run and the other as Direction using a 2 button remote. With the control software “play back” the button presses - and add a repeat on the Run to last the 15 seconds. It simulates holding the button in for a period.
Manual control is also possible if you use the latch functions on the receiver board but then you can’t tell what state you are in and may go out of sync with reality.
A simpler but more expensive option is to use a Sonoff 4ch Pro. It has the logic, Wifi control and an RF receiver built in and can run autonomously without an automation system. Perfect for gate applications.
Just something to add… 433Mhz is pretty congested. The first button press doesn’t always get through and you might have to send repeat signals. The 15 second repeat will solve your problem… but potentially kill your neighbour’s wireless energy meter or weather station transmission so be considerate towards other automators
