Require special type of relay.

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Z2TT

Joined Oct 7, 2010
2
Hello,

I have read the relay write up but have not been able to find the type of relay I need to function in a certain way. I will try to explain as simple as possible.

I need a relay that controls continuity to 2 outputs, and they are labeled A and B, but normally does not give continuity to either. So it would be like this :



Now Once The coil is energized, I want it to give continuity to A for ONLY 1 SECOND, and then go back to normal.

But then, When the coil is de-energized, I want it to give Continuity to B for 1 SECOND ONLY, then go back to normal.

Then when energized again repeat the process - Back to A for One Second.

Is this possible and is there such a Relay?
Any ideas welcome.

Thankyou.
 

KMoffett

Joined Dec 19, 2007
2,918
Outside a PLC (programmable logic controller), I don't think you will find "a" relay that will meet your spec's. A couple of details: What powers the coil? What voltage (AC? DC?) and current are the contacts supposed to switch?

I think two 555s (or a 556) configured as positive and negative edge-detector monostables driving two SPST relays would work.

Ken
 

Thread Starter

Z2TT

Joined Oct 7, 2010
2
DC Power, current would be pretty low.

Coil will be powered by a wire that formerly supplies constant power to the vehicles ECU, however the immobilizer i installed cuts power to this wire, now upon the immobilizer "arming" itself and cutting power flow through this wire, I want an event to happen.

So

1. Immobilizer arms.. cuts power through ECU +12v wire

2. At this time i want a certain wire on the cars system ('A' in my mspaint pic) to be grounded for 1 second, so that is why i want a relay to detect the +12v wire losing power, then ground a certain wire for 1 second.

So sequence of actions.

- Immobilizer arms, cuts power to ECU Wire
- "My Relay" detects loss of power to this wire, grounds wire "A" for 1 Second

And for disarming

- Immobilizer disarms, power to ECU wire is given
- "My Relay" detects power on this wire, grounds wire "B" for 1 second

In a nutshell I need - A relay that detects presence and absence of voltage on a given wire, and upon detection of presence and absence of power to that given wire, the relay will provide ground to 2 different wires for 1 second only, the wire that is grounded out of the 2 is determined whether the relay detects presence or absence of power on it's trigger wire.
 

marshallf3

Joined Jul 26, 2010
2,358
Can't think of a relay with a "center off" position but they did exist at one time.

Chances are you're going to have to build some sort of tri-state flip-flop circuit.
 
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