12v relay with time delay and reverse polarity

[john2k]

Looking for some help in wiring up a 12v relay for my car.

Basically, I have a 12V relay that is activated with my windscreen washer circuit. So when the washer pump is active, the relay activates. Problem is that the relay only stays active for the period of time that I hold the washer stalk down. The moment the relay gets activated, I want it to provide power to my device for 3-4 seconds in one polarity and then for another 3-4 seconds I would like it to reverse the polarity before turning off completely. And also if for some reason the windscreen washer was to be activated again while the relay is still cycling through the first 3-4 seconds then it should not re-activate.

Would really appreciate some help on this.

Many thanks

 

[Colin Mitchell]

Your request is not clear at all.
Can you repeat it in Pigeon English?

 

[john2k]

Your request is not clear at all.
Can you repeat it in Pigeon English?

LOL ok, let me try and explain in another way

I currently have a 12V relay. This relay is turn on and off by the connection from the 12V washer pump. When the relay is turned on, I want it to remain turned on for 3 or 4 seconds even if the supply that powers the relay is turned off. I also want it after the 3 or 4 seconds, to reverse the polarity (make + minus and minus +) for a further 3 or 4 seconds before completely shutting down. And it should not restart if the power to the relay is turned on again while this is happening. If it has finished the process then it can do the same thing again when the main power to 12V pump is active again. Am I making a bit of sense now?

 

[Colin Mitchell]

" Am I making a bit of sense now?"
Not really.

The terminals of a relay can be wired so that a motor turns clockwise when the relay is energised and turns anticlockwise when the relay is not energised.
You need another relay to supply power to the motor to be able to turn the motor OFF.
You can use a 555 chip to activate the second relay so that it remains active for 3 seconds after you take your finger off the switch.

 

[Garypcv]

" Am I making a bit of sense now?"
Not really.

The terminals of a relay can be wired so that a motor turns clockwise when the relay is energised and turns anticlockwise when the relay is not energised.
You need another relay to supply power to the motor to be able to turn the motor OFF.
You can use a 555 chip to activate the second relay so that it remains active for 3 seconds after you take your finger off the switch.

I might be wrong ,which is maybe 90% of the time, but is he trying to describe an 'intermittent' windshield wiper circuit ?

 

[hevans1944]

I might be wrong ,which is maybe 90% of the time, but is he trying to describe an 'intermittent' windshield wiper circuit ?

Hmmm. Maybe, but why the reversing polarity? Wiper motors run in one direction only. The oscillating wiper blades is a mechanical function.

 

[Martaine2005]

I think you are all missing the point!
He wants to squirt his windscreen to clean it and then suck the water back!!
Saves keep filling the washer bottle..
Obviously he has a water meter! This only happens in the UK. We pay for the water, pay to clean it and then pay to use it again! Only, we do this hundreds of times!!


Martin

 

[Garypcv]

Hmmm. Maybe, but why the reversing polarity? Wiper motors run in one direction only. The oscillating wiper blades is a mechanical function.[/QUOTE

 

[Garypcv]

ROFLMAO !!! he wants to re-use the water he just washed windshield with ??? This will be done while the vehicle is stationary? Any speed over 20mph.....oooops 32 kph for you blokes on that side of the pond, will get blown off due to the wind....
Lol. This is a trick question isn't it ??

 

[Garypcv]

I think I just solved your dirty water problem: 20 gal fish aquarium mounted on roof of vehicle. Water is filtered while it circulates thru the tank, leave lid off so you can aquire fresh water whenever it rains and for dinner, you just brought home the freshest fish possible! (y'all do eat fish over there?)

 

[AnalogKid]

Actually, the description in post #1 is perfectly clear. The relay reversing output part just went by in another thread in Circuit Help.

One solution would be a CD4093 or CD40106 making two monostables (non retriggerable) in series, each one driving a SPDT relay. Note - this circuit needs power filtering, transient protection, etc.

ak

 

[hevans1944]

Actually, the description in post #1 is perfectly clear. The relay reversing output part just went by in another thread in Circuit Help. ...

I didn't find it in Circuit Help, but there is a similar discussion from the same poster (@john2k ) in Electronic Projects here on September 11, 2012... more than three years ago! Wiper blades must have worn out by now waiting for a solution.

 

[AnalogKid]

https://www.electronicspoint.com/threads/changeover-switch-relay.276138/

CDRIVE's output stage in post #24 was one possible solution for that question, and is perfect for this one.

ak

 

[Garypcv]

I didn't find it in Circuit Help, but there is a similar discussion from the same poster (@john2k ) in Electronic Projects here on September 11, 2012... more than three years ago! Wiper blades must have worn out by now waiting for a solution.

Or he blew up the drive motor by all them slams into reverse....lol