pulsate voltage on/off

I am attempting to wire up a gsm relay switch as a project. I will wire the output to a spare key fob. I can specify how long the signal from the gsm relay will be on. On my key fob I have to hit the lock button 3 times to start the vehicle. What I need to do is once the signal from the gsm relay is on, I need to be able to pulsate it on/off 3 times at 1 second intervals. So, how can I pulsate the signal from on to off and repeat that 2 additional times?

the only way i know of without buying a device to do it for you would be with using multiple relays wired together with some resistors and capacitors. ill see if i can find an exact diagram but basically you will need 3 normal spdt relays, 3 1 amp 15K resistors, not totally sure on the value, and 3 capacitors each with a different value.

the way it works is the capacitors give the relays a time delay based on their value so by having three different value capacitors you can set them up to give you a pulse every second for 3 seconds. ive only made one of these circuits before and ive never wired a bunch of them together but i think it will work. let me try and find the diagram.

-------------

Diagram

ok this is the diagram i remember but i was wrong to think it was a time delay circuit. its actually just a timer. i dont think it will work for what you are trying to do, not easily anyway, you would need relays on relays on relays to make this work like you want. it will give you the delays you want but it will not pulse, it only stays on or off after the delay. im not saying it cant be done this way but it will be extremely complicated and im sure there are better ways to do this.

do a search at the top for time delay relay and you will get some other diagrams that involve transistors and capacitors that should be more of what you are looking for.

-------------

being told this can be done with a 555 ic. i have no clue how or where to even begin with that. any commercials options that will do what i need?

i know a PAC TR-7 will do as many pulses as you need but im not sure if the timing between each pulse will be enough to work.

-------------

Not that I understand why you want the conversion (ie, what does one pulse do, and if nothing, why not?)


IMO it's a job for a PIC (PICAXE etc - eg, the 8-leg 08 version 08M, 08M2 etc).

Next choice would be a timer feeding a 4017 or two.