negative potential

Thank for the replies to my previous post. I have another question however, that is probably pretty stupid. I looked through the other threads on installing door switches for actuators etc., and I keep seeing negative pulse to switch the relays that drive the actuators. So a couple questions:

1) How do you generate the negative potential that goes to the relay?

2) For the pulse do you use a momentary switch or do you have to design a circuit to pulse the current? How long should the pulse be? Doesn't it have to be as long as the actuators need to travel? Does this mean I should a momentary switch?

Thanks again and my apologies if this is a repeated question, I really couldn't find it elsewhere.

1) the negatifve pulse is generated in two ways

a) by the alarm/doorlock/keyless entry brain/lock/unlock switch at the door (it'll produce anywhere from -500mA to -250mA) upon locking/unlocking

b) OR ... the alarm/doorlock/keyless entry brain/lock/unlock switch will produce a positive + signal and this will drive a relay that will use GROUND as the ultimate negative potential that goes to the relay...

Basically, in the circuit for the actuators, there is a + (positive) charge at the top of the potential, and using ground as the negative potential will allow the charge to fall down the potential towards ground.  Using ground as the negative potential allows for this potential to exist and creates a magnetic field in the solenoid.

2) A momentary switch should be fine; most keyless entry brains produce negative pulses (for lock and unlock) that are anywhere from 250ms to 750ms (milliseconds).

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" b) OR ... the alarm/doorlock/keyless entry brain/lock/unlock switch will produce a positive + signal and this will drive a relay that will use GROUND as the ultimate negative potential that goes to the relay..."

Thanks for the quick response, I'm still a bit confused though I commented on a picture presented earlier that maybe will help illustrate my confusion.

Do you see how 87a on both of those relays are connected to a perpendicular line with little narrowing lines pointed downward like an arrow --> that's the electronic symbol for GROUND.  The actuators REST (in this diagram) at ground (terminal 30 is normally connected to the 87a terminal), and during unlock/locking the circuit is connected from terminal 30 and 87 (12 volts), which supplies power to the actuators to move the mechanical doorlock whichever direction.

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That three prong switch -- the blue and green wires .. those should be grounding (or negative wires) when you press either lock or unlock -- they may REST at positive, but when you press the button (the swtich in lock or unlock) it must connect the circuit to ground (negative).

that switch has to be grounded somewhere, otherwise, if you trace it back to the relays, it's just providing a positive charge at all times to the 85-86 relay solenoid.  When pressing the lock or unlock (hence three prong, two of the prongs are positive, one is ground) the relay will see ground and cause the circuit to switch from 87a to 87 --> initiating the actuation of the actuators.  And that three prong switch should be spring loaded on both sides --> i.e. it's not a flip switch --> it's like a dual-momentary switch as is a typical lock/unlock switch on any factory power door lock switch

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any i don't quite understand what you mean by the GREEN/ blue wires being "positive coming off your battery"

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This is what I'm thinking, should that com be ground?

Obviously A/B would be lock/unlock. If that is correct does that mean I need to leave the switch in the middle position after locking/unlocking?

COM should be connected to CHASSIS GROUND, according the previous diagram of the unlock/lock relays.

It looks like you have a toggle switch -- I have never seen that used for an aftermarket door lock system.  I've only seen momentary switches. 

Do you see how if COM is always supplying 12 volts (either in the COM-A or COM-B circuit setting) .. then it'll always ben providing a 12 volt positive + charge to the 85 terminals on the unlock and lock relays and therefore the circuits of those relays will NEVER be switched from 87a-30 to 87-30 --> therefore they'll never initiate the actuators.

Which directions are you using to install this system?

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The 12 volt power for the actuators is coming from terminal 87 on each of the above relays.

If you use a toggle switch, you can't leave it in the middle -- it's either up or down.  Therefore the circuit will always be drawing juice and you'll blow a fuse.  I'd look into a momentary switch

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https://www.radioshack.com/product/index.jsp?productid=2062530&cp=&sr=1&origkw=momentary+switch&kw=momentary+switch&parentPage=search

This swtich is $5.00 and returns to center after you toggle up or down.

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Sorry that was the only schematic I could find for a switch, I'd be using a momentary switch I should have cut that part out. So for the switch side, I'd connect COM to ground and then pass that onto the relay?

I don't have any directions, I am trying to put it together using this site. I bought a Viper 350HV, and Crimestopper 610 actuators to put in power locks. Hooking the alarm to the actuators isn't a problem because the alarm comes with (-) outputs but adding a switch to generate the same sort of output threw me off.

No problem.

Yes, definitely use chassis ground for COM, this will send a negative or grounding signal to either the blue or green wires coming off the DPDT momentary switch depending on whether your unlocking or locking. 

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I really appreciate the help, if you are ever cursed enough to be in Saint Louis I owe you a drink.

Re your relay diagramme, if you want neg outputs at 30, disconnect 87a  (dont use) and make 87 NEG input ie wire to ground.