Positive to Negative / Vanagon door lock

I have an 87 Volkswagen Vanagon with power windows and locks. I use a TWINDOW roll up module for my express window functions and find the TWINDOW to be the best module ever.
    I have been playing with using the constant 12V output of the lock actuator when the door is locked. My goal is to raise the window with the key when locking the door. I need to convert the + signal to a - signal which is easy with a relay. When I do that the Relay remains hot always and sucks my battery.
    I've recently bought a "Adjustable 0-10 Seconds Time Timer Delay Module Switch NE555 Oscillator DC 12V U" which works fine but remains hot at all time when the door is locked. I want to find some way to shut it off after it does its job. I also want to add a relay in,that will be NC at rest and NO with key on to prevent the window going up when the door is locked during normal operation.
    I have looked at the 528t pulse timer and can not see its function for my use. It looks to me that the NE555 does almost the same function as the 528T.
    I hope this all makes sense. Any answers are appreciated. I have used this forum for years to solve my electrical incompetence and look to the pros for guidance.

The pulse timmer will connect to the Negative from the door lock direct and then set it for the maxium time to completely roll up the window , but if the windows is not all the way down you will continue to power the window when all the way up until the 528t times out.
A 529t or 530t will be a better match for you desire and will load out and shut off when the window hits the top.

The TWINDOW module handles all of that as it senses over powering and shuts off.
   What I am trying to do is find a way for the relay to shut off after it does its job.
    I let a relay stay latched last night and shot it with an IR gun and it was 108 Degrees F. I was hoping to put it in a project box, but maybe I need a smaller relay. The one I am using is a regular 40/50a relay.
    Can someone point me to a mini relay that is normally closed?

Stacy     


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If your relay is staying engaged, test the door lock actuator wires. If the wire you are connected to stays positive after you press the lock button (even after you've taken your finger off the button), you can use a capacitor inline with your relay coil.

Something like this might work:

https://www.the12volt.com/relays/relaydiagram44.html

If the lock actuator wire does not stay positive after you've taken your finger off the button, do away with the 555 timer and just use a relay:

https://www.the12volt.com/relays/relaydiagram9.html

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My ex once told me I have a perfect face for radio.

So I have all the parts to build this and have been studying its function.
    I need some help understanding how it works. I understand that the Capacitor releases its charge and then in turns give a Momentary output which powers the module. But if the input Pos input is constant wouldn't it just reload the Cap and keep on going?
    My door lock system is different from the standard 5 wire relay which just uses a momentary signal. The signal is constant 12V when locked and constant 12V when Unlocked on each of the supply wires.
    Am I missing something here.

Stacy


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The capacitor isn't releasing, it's charging due to the flow of current until charged then no current flow and relay coil de-energizes. And stays off until 12v is removed allowing cap to discharge thru resistor to reset. As the resistor can't pass enough current to keep relay energized but holds back enough current to keep capacitor charged until 12v is removed.

Thank you. I will now go ahead and build it and hope for the best.
Luckily the components are cheap enough.
    I have built a few things from diagrams here and they have always worked well, so here it goes.

Stacy

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So I've built it and it works. If I doubled the Capacitor would I also have to change the resistance as well? If so could I just add another resistor on the end or would I have to get a different resistor?
     I will install it and see if it is enough of a signal to do the job?
     Off to R/S for a larger Capacitor or just another 1kUf?

 Stacy

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If you increase the value of the capacitor, it increases the time it takes to charge (which increases length of the momentary pulse output by the relay).

As Lurch said, it is the job of the resistor to discharge the capacitor once power is removed, so it has nothing to do with the timing.

The relay coil acts as a charging resistor for the capacitor. So, with a larger value capacitor, to keep the pulse the same length, you could wire a resistor in parallel with the relay coil.

If you want to learn more about basic timing circuits, read about capacitors and time constants. Transistors are helpful too.

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My ex once told me I have a perfect face for radio.

As Howie II always says KISS.
So 1 larger cap is better than 2, less failure points.

A "lower" or parallel resistor(s) can used up to the point that the relay will turn on due to enough current to close the relay. If the larger cap bleeds off (Resets)to slow.
But this will also increase the ma consumed while locked (+12v) is connected to relay, so go up on cap first and resistor last. As resistor is always bleeding just not faster than the cap can charge. So the higher, the better.
But a faster bleed (Reset) will slow cap charge (on time) also.
Need to find the ratio that works for you application. Miniuim cap to achieve time on with the highest resistor that can bleed cap to Reset.

So I upped the Capacitor to 2400uF and doubled the resistors to increase my energized time. It seems to stay on just a skosch longer now. I have only bench tested it so far. But it seems to work fine everytime. I have it in a sealed Project Box.
Before I built this and what caused me to build this was a constant on relay which was switching + to -. But when I hit the door lock with the vehicle running sometimes it would send the window up. As I think about it now, the unit should be blocked out when the ignition is on.
   In my project box I wired a N/C relay to prevent this from happening, but I think I have over thought this.
    I will install it and see what it does.

Stacy


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