changing a double pulse to a single?

I'm working on replicating what another member had done, which is to adapt a cell phone to trigger the start of a remote start.

I've got everything working but the only problem is that the phone always sends a double pulse and I need a single pulse to start the car, as it is it starts the car and immediately shuts it off.

I've been doing some reading on the forums and trying to make sense of the relay diagrams and what others have done. But still need some help.

The phone sends a double pulse of 1.5v (at 420ma I think) is there a way to install a capacitor on that 1.5v line to store both pulse and then release it to trigger the 1.5v solid state relay?

Can you not programme the R/S to accept a double pulse? You can do this with DEI product in fact their default is double pulse.

khisanthax wrote:

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I'm working on replicating what another member had done, which is to adapt a cell phone to trigger the start of a remote start.

I've got everything working but the only problem is that the phone always sends a double pulse and I need a single pulse to start the car, as it is it starts the car and immediately shuts it off.

I've been doing some reading on the forums and trying to make sense of the relay diagrams and what others have done. But still need some help.

The phone sends a double pulse of 1.5v (at 420ma I think) is there a way to install a capacitor on that 1.5v line to store both pulse and then release it to trigger the 1.5v solid state relay?

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You can try using a capacitor and a resistor. The capacitor would be wired in parallel to the circuit (+ side of cap to your r/s trigger, - to ground) and the resistor would be wired between (in series) the cap and your remote start. The values of the resistor and cap would have to be played with a bit to see what works with your setup.

Other ways would be a jk flip-flop or the crude equivalent a latching relay setup.

i'm using two relays to get this working as is, does the cap neg have to go to the triggering wires ground or any negative wire?

how would I go about figuring what specs I need for the cap and resistor? is there a specific formulae?

I have a viper alarm and the install manual made no mention of changing the number of pulses, it only said to use a momentary switch to change the pulse ... which I did not understand ...

Look in the programming sheet, it's the WHITE/ blue on the Viper although I'm sure the default is 2 pulses anyway.

then maybe the installer changed it, because as it is now it's one pulse. I've already connected the cell phone to the car, and with two pulses the car starts and then gets turned off immediately, which is also confirmed by my two way remote.

If it can be programmed or re-programmed to use two pulses i would have to use the two-way pager since I don't have a programming terminal, which for me might be too scary especially if I mistake what menu I'm supposed to be on and change a wrong value. But I'll look into it.

Yes there is a formula for RC circuits, for what you need this calculator will let you figure roughly what combo resistor/capacitor values you need. You want the time constant to be long enough that both pulses happen in that time frame, maybe even a little (second) longer to ensure the cap keeps the charge high enough to not pass the two pulses, just one long one.

thanks for the link and the suggestion, I hadn't thought of that but would have most likely hit that bump in the road.

so, if i understand this correctly, the capacitor will store the two pulses of 1.5v over lets say 4 seconds and then discharge 1.5v to trigger the solid state relay?

That's the idea, actually though with the first pulse the relay will trigger and stay triggered until the capacitor discharges. The second pulse should come and recharge the capacitor before it discharges.

Your solid state relay is a PCB type deal? If so you could utilize a JK flip-flop to accomplish the goal if the cap-resistor fails you. The JK flip-flop is an IC that can toggle it's output between + and - every time a pulse is applied to it's clock input. In your case the first pulse would set the JK flip-flop + or - and the second would flip it.

So with your car phone remote start, you call your car to have it start? Who pays the phone bill, you or the car?

thanks, I'm gonna line the cap on the positive trigger wire and negative trigger wire and the resistor connected inline immediately after the cap.

Well, it's a $10 phone, so I can get prepaid minutes or prepaid text without having to pay anything monthly and it all rolls over to the next month. But I'm not gonna use that right away, first i'm gonna use the built in calendar feature as an advanced timer.

I'll look up the jk flip-flop if this cap/res isn't simple enough for me.

Get a PAC TR-7 or Viper SmartStart

the smartstart is what gave me the idea however I found it to be too expensive and it doesn't work on the windows mobile operating system, at least not when I looked into it.

But .... I got it all working and the car safely turns via remote start via cell phone call, txt or calendar function (what i'm using now).

Thank you all, sincerely, for the help.