Ok, thinking about a semi-automatic torque converter circuit...

[Jay2TheRescue]

Ok, I was thinking... On my 81 Buick the torque converter no longer locks because of some problem in the computer which I don't care to spend the time to trace. I thought of a toggle switch, but that's just not me. I know I'll forget and leave it on, and cause myself problems. I spent some time sketching out possible circuits on notebook paper today, and when I found one I was happy with I made a prettier version in paint for everyone to look over.

I'm proposing to use (2) 12v SPST relays. One normally open, one normally closed, and a SPST monentary contact switch. The switch will energize the relay. Once energized the relay will hold itself closed until the brake pedal is pressed, energizing the second relay, and breaking the ground on the first, thereby resetting everything until the next time the button is pressed. I guess if this works out I could use a lighted switch, and have the light glow when the converter is locked. Anyone see any flaws in my logic here?

Thanks, Jay

[GasSavers_BEEF]

it won't hold itself closed unless you have a set of contacts across that switch.

similar to a start stop station.

----l/l-----l l-----(load)---

this is what you have right now with the first relay being actuated by the brake pedal and is normally closed, the second being the relay remotely operated by the switch but once you release the switch the circuit is broken.

you need to parallel a set of contacts from the second relay (the normally open one but not the same contacts that you are using) across the push button so that it will hold itself until the brake pedal resets itself.

----l/l-----l l-----(load)---
............l.......l
............--l l--

that last one is terrible. I may look up a start stop station ladder logic drawing if I have time. ignore the dots as this site won't let you put spaces.

*edit* sorry for the large file but it was the best one I could find with a small amount of time. http://www.sea.siemens.com/step/pdfs/cc_1.pdf there is a drawing on page 17.

*edit again* scratch all that, I noticed that you have it set up that way. never mind.

[dkjones96]

http://www.streetperformance.com/par...219-60109.html

I only know one person using that but it does work!

[Jay2TheRescue]

BEEF - all I can say is you lost me... Won't the relay hold itself closed once its energized by the pushbutton? What does the pushbutton have to do with the relay breaking the ground to the primary relay? I have a tendency to make things complicated, but I think you may be worse than me...

dkjones96 - I have seen those kits before, but I can probably build what I have posted here for almost nothing as I already have most of it in a spare parts bin. The kit you mention costs $160.

[theholycow]

Only a latching relay would hold itself closed once it's energized by the button. Common relays are normally on or normally off, and only hold the opposite state as long as they remain energized.

[dkjones96]

I was thinking of a latching relay but every time he hit the brakes then let off and went back onto them it'd throw the system out of whack.

What you could do is a normally open DPTS relay and a normally closed SPST. You can make a 'latching' relay by running your 12v power through one pole then through the coil. You bypass the relay switch with the momentary switch and put the normally closed relay in line with those as an interrupter when you hit the brakes. Your load then goes on the second pole of the DPST.

The system starts in the off position, you press the button and it bypasses the double pole to apply power to the relay, when it turns on it will latch and hold until the other relay switches and cuts power to the first coil. DIY latching mechanism.

[Jay2TheRescue]

Yes, but I have the output +12v going to to top where its also energizing the coil... In theory it should hold itself closed, right?

[GasSavers_maximilian]

This looks like a job for color coding! Red is +12 VDC, blue is ground, black is floating. The left relay could be replaced by a pull down resistor I would imagine.

[Jay2TheRescue]

Thanks for the color coding... You understand what's going on in my brain. That can be scary at times. I don't like the resistor idea because what "should" happen and what does happen can be very different in a 28 year old car.

-Jay

[dkjones96]

I don't think the second relay can be replaced.

Don't forget to run a resistor in line with the relay coils. The 12v relays at radioshack are exactly that, 12v relays. I used 100 ohm to bring the 14.x volts from the charging system down to a reasonable level of I think 11 volts(read voltage dividers, I used the first example, a series divider). I used the little blue SPDT relays on protoboard with cat5 hookup wire. You'll be hard pressed to find single throw anything anymore.