Right,here's what I'm trying to do. I've got a VW Golf mk.4 that has had the conventional mechanical door handles removed from it and replaced with an electically operated solenoid,the solenoid in question is not really a solenoid but a motor and gearbox (it's used to remotely release the fuel filler flap on the same car if you need to know).
At the moment as shown below it's operated by an infra red beam break unit that fires the solenoid when you put your hand in and break the beam (it's switched off when the alarm is armed).....
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It's just a standard off-the-shelf kit from Maplins which I spent a lot of time testing this on the bench before going anywhere near the car with it so knew it was capable of doing what it had to do lots and lots of times.The problem I have now it's on the car is as I thought might happen is it's very sensitive to dirt on the IR tx and rx causing the door to open when it's not supposed to,not when the car's being driven though as it's switched off as soon as I turn the ignition on.As I've yet to use the car with them fitted in heavy rain I can only guess at what's going to happen,but I don't think it'll be as reliable as it needs to be.
So...................what I've decided is to simplify it as much as possible and have just a switch and relay to fire the solenoid,but I'm limited to a depth of about 5mm max.I've been looking at some ultra low profile tactile switches,but once I've mounted them on a PCB and put some sort of waterproof covering over the top of them I'll have used up all of that 5mm.
My plan is to use or make some sort of membrane switch,and as I can't seem to find anything commercially available the right size it looks like I'm gooing to have to make one.
The main criteria is that when closed it must be as close to zero Ohms as possible as it has to drive the relay which draws about 50ma without any other associated circuitry.All Google results suggest the idea with conductive foam but as that only drops to about a few hundred Ohms that's out of the question.
Sooooooooo........... has anyone got any ideas how I can do this or even better to save me some time which I don't have a lot of at the moment,is there any off-the-shelf product I could use? The most important things to remember are a maximum thickness of 5mm and it it must be able to handle more then 50ma.
Thanks in advance,Chris.
At the moment as shown below it's operated by an infra red beam break unit that fires the solenoid when you put your hand in and break the beam (it's switched off when the alarm is armed).....
**broken link removed**
**broken link removed**
**broken link removed**
It's just a standard off-the-shelf kit from Maplins which I spent a lot of time testing this on the bench before going anywhere near the car with it so knew it was capable of doing what it had to do lots and lots of times.The problem I have now it's on the car is as I thought might happen is it's very sensitive to dirt on the IR tx and rx causing the door to open when it's not supposed to,not when the car's being driven though as it's switched off as soon as I turn the ignition on.As I've yet to use the car with them fitted in heavy rain I can only guess at what's going to happen,but I don't think it'll be as reliable as it needs to be.
So...................what I've decided is to simplify it as much as possible and have just a switch and relay to fire the solenoid,but I'm limited to a depth of about 5mm max.I've been looking at some ultra low profile tactile switches,but once I've mounted them on a PCB and put some sort of waterproof covering over the top of them I'll have used up all of that 5mm.
My plan is to use or make some sort of membrane switch,and as I can't seem to find anything commercially available the right size it looks like I'm gooing to have to make one.
The main criteria is that when closed it must be as close to zero Ohms as possible as it has to drive the relay which draws about 50ma without any other associated circuitry.All Google results suggest the idea with conductive foam but as that only drops to about a few hundred Ohms that's out of the question.
Sooooooooo........... has anyone got any ideas how I can do this or even better to save me some time which I don't have a lot of at the moment,is there any off-the-shelf product I could use? The most important things to remember are a maximum thickness of 5mm and it it must be able to handle more then 50ma.
Thanks in advance,Chris.