Door switch alternatives

[Bitsyncmaster]

I pulled the upper door panel off and was looking for a place to mount my mercury switch. There is one flat panel that looks like the correct angle but I have to make a new switch with the switch mounted so the terminals are not on the tilting end.

My drivers door latches real easy on the front latch but not the rear latch. So even if I took off the rubber cap so it would indicate the front latch is not closed, you would still need a rear door switch to sense that latch.

[Ron]

I'd personally leave it all as is OR make the dome lights come on when the door was, say 1/2 way or more open and forget battery drainage (Merc switch would be great). Then monitor the four door lock positions right at the latch arms with accessory powered IR sensors (cheep, simple, and power usage is not a problem even if hot all times, but no need to be anyway).

[Bitsyncmaster]

I'd personally leave it all as is OR make the dome lights come on when the door was, say 1/2 way or more open and forget battery drainage (Merc switch would be great). Then monitor the four door lock positions right at the latch arms with accessory powered IR sensors (cheep, simple, and power usage is not a problem even if hot all times, but no need to be anyway).

That would be the best solution but it would require some wires to separate the lights and the dash indicator.

Here is my next switch. The black tape is just for potting the unit.

[Farrar]

I got tired of fooling with that circuit and just put it on a toggle switch. Although I like this functionality, I am also adding a remote control to it. Should make it easier to find my car in a lot full of DeLoreans.

[Bitsyncmaster]

Here is the installed mercury door switch. Just held on with double sided carpet tape but I have some double sided "servo" foam tape on order for the permanent install.

[Bitsyncmaster]

Well I'm still learning things as I make modifications to my car. It turns out that mercury switches have a very large switch bounce when used on our slow opening door. I can see the door lights flash on and off when the door is passing through the half open position where the mercury switch transitions. I had to make a software change in my dome light unit which was using a deglitching routine for the normal door switches. Normal mechanical switches also bounce but the timing is way shorter for those. The mercury switch timing will sometimes exceed 400 ms.

I guess the ball of mercury hits the end of the glass tube and bounces like a steel ball would bounce if dropped on a hard surface. Probably longer contacts in the switch design would reduce or eliminate this problem.

[tommyrich]

I really like my Magnetic switch setup. It uses a threaded barrel reed switch that allows the switch distance to be precisely adjusted (to activate the dash light on the first latch position for example). And, since it does not make contact with the door itself, it will never wear out or go out of adjustment.
The downside is the switch cannot handle a lot of current, so I designed a small relay box that is activated by the switches. The relays take no power when the doors are closed, and there are separate circuits for the drivers light and buzzer circuit, using a double pole relay. The red/green leds are used when adjusting the distance to the small magnet that is glued to the door plate where the plunger usually contacts. I added a "cutoff" switch in the (now) spare hole in the drives side to turn off the lights when I have to doors open for a long time.
I have used this circuit for over 4 years and have never had a problem.
Tom -

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[Bitsyncmaster]

I finally got my order for the "servo tape'. Good thing I bought this because the carpet tape did not hold on the stainless (held great on the epoxy switch). Anyway, went for a drive around the neighborhood and never saw any dome light flash. So it looks like the mercury switch will work. Guess I will do the passenger door the same way.

[Bitsyncmaster]

I had to make some software changes to my dome light unit for it to work with mercury switches on the doors. The problem is long switch bounce when the doors are open and closed. The first problem was I treated a door switch action of less than 400 ms. as a glitch and turned the unit off. So I could get a few times when the door was open but the unit would not power up. The second problem was after the door was left open and battery saver mode was timed out. Then when I slowly shut the door I could get it into program mode. Standard door switches will not have these problems.

So if you want to use mercury switches on the doors, you will need to send me your older unit for a software update. New builds will have the new software.

[Bitsyncmaster]

I finally got my order for the "servo tape'. Good thing I bought this because the carpet tape did not hold on the stainless (held great on the epoxy switch). Anyway, went for a drive around the neighborhood and never saw any dome light flash. So it looks like the mercury switch will work. Guess I will do the passenger door the same way.

That "servo tape" has been holding fine for 5 years.