Autostop reversible motor switch circuit

Thread Starter

Raveboy81

Joined Aug 22, 2017
2
Hi all, this is my 1st post so apologies if it's in the wrong section. I've designed and built a tv lift to raise a tv up out of a cabinet in my VW TV van. It's a 12v motor and I want to momentarily trigger the UP voltage with it then switching off via a uSwitch when it reaches its upper travel limit. The same would then work for the down travel. I Came up with the circuit attached using standard auto 12v relays but I don't think I have the grounding switched properly. I just want the UP and DOWN moment switch to act as a trigger and to not have to hold it the whole time. Any suggestions or ideas people??.
Many thanks in advance,
Steve
 

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MaxHeadRoom

Joined Jul 18, 2013
23,339
You want a dual momentary PB, each will (self) latch in a relay for each up and down stroke, a limit N.C. sw at each extent of travel which will unlatch the relay.
Or you can set it up with both limit switches in series with the motor and a reverse diode connected across each.
Max.
 

Thread Starter

Raveboy81

Joined Aug 22, 2017
2
Hi Max, thanks for coming back so quick, can u tell me what PB stands for ? I'm not familiar with that acronym.
Steve
 
It generally falls under the "chicken coop door" problem or the "door actuator" problem. Once you have the limit switch issues solved and the swiches can handle the coil current, two automotive relays give you, up, dn, brake, brake depending on the two relay states. Once, they reach the end the relay drops out.

So, what you can use is an "impulse relay". that would change states each time it's pressed. You can also use a dual coil magnetic latching relay for the up/dn two PB method.

Remember, reverse biased diodes across the relay coils for spike protection.
 
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