Looking for a proper state change relay, but I'm struggling! Help!

Thread Starter

Daniel Worsley

Joined Mar 27, 2018
3
Hi guys

I have recently fitted a mini windows 10 PC in my van with a touch capacitive screen built into the dashboard, I'm using it for job management, emails, satellite navigation and for steaming music.

The install is pretty much complete, however Iv had to put a temporary momentary push button in to put the PC to sleep and wake it back up for when I need it.

Ideally I want the PC to wake up when I turn on the ignition, then put the PC to sleep when I turn the ignition off. So I need a relay that will output a pulse (1-2 secs) for when the ignition goes live, then output a second 1-2 sec pulse when the ignition de-energises.

I'm struggling to find a relay that will do the job. Iv bought 2 different solid state relays online and they both only pulse when the input is energised, they both don't output anything when the input is de-energised.

Iv tried searching online for State change relays but can't find anything.

Am I using the correct term for the relay type??

Many thanks
 

K1W1

Joined Jan 13, 2018
13
You probably need two relays connected in parallel;
1 - applies a pulse on ignition turn on
2 - applies a pulse on ignition turn off.
 

crutschow

Joined Mar 14, 2008
25,631
Can you post info and the instruction manual for the relay?

My thought is to use an XOR gate configured to generate a pulse on both power application and power off.
 

Thread Starter

Daniel Worsley

Joined Mar 27, 2018
3
The relays I have didn't come with instructions. There is no setting jumpers on it, only a single potentiometer for adjusting the pulse duration.

Il have a search on XOR Gate and post results. Thanks guys
 

crutschow

Joined Mar 14, 2008
25,631
What are the inputs to the relay?

Below is an example XOR gate circuit that produces a pulse on both the rising and falling edge of the input.

upload_2018-3-28_11-15-25.png
 

Thread Starter

Daniel Worsley

Joined Mar 27, 2018
3
Just a single 0v trigger, the relays give a single pulse the trigger input circuit closes, but nothing happens after the 0v trigger is removed, which I need the relay to pulse again.

I can't find any built relay boards with xor gate, only chips. Is it likely il need to build my own?
 

crutschow

Joined Mar 14, 2008
25,631
BASCOM has a free basic interpreter for the ATTINY (makes writing code almost trivial )-
Only if you already know the basics of programming. :rolleyes:

And I don't see why you would want to replace a single CMOS gate, resistor, and capacitor, with a microprocessor. :confused:
Seems like a clear case of overkill.
 

danadak

Joined Mar 10, 2018
4,057
The gate idea an excellent one if its schmitt But plain CMOS gate where
input comes into threshold region, in an auto environment, lots of noise,
will produce multiple pulses, worst case could put it into oscillation..Needs
some hysteresis somewhere in control loop.

As far as using a UP, timing potentially does not vary all over the map.
And down to 17 cents (although I think that implies programming in C or ASM
due to memory size, would have to investigate) and eliminates the timing electrolytic.
Not to mention ability to sense for low batt issues......

Regards, Dana.
 
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