Like I said a gotya, remove carefully.

Didn't Mad Max have one of these attached to his car?

Rich Ball
'76 Midget
Everett, Wa

Ours too, Pat. Much trouble caused in our "yout" with various contemporary artists' issuances: Stones, Airplane (After Bathing at Baxter's " was a perennial fave), Buffalo Springfield...
you get th' picture.

maybe or it's for communicating with the mother ship

Hey guys, I did a search for diy vacuum car alarm the other day and found a site that was written by somebody that I thought might be able to identify the device. I sent a link to this what is it? thread to Ron, the author of Car Alarm Immobilizer and this was his reply to me:

The most sensible place to start - is with the words of the man who built the device. If the device is not disabled then - after a couple of minutes - the electrics are shut down.

I think Nelson is on the right track. I suspect that the glass tube contains some sort of thermal delay - like a thermostat with a built-in heater. When it reaches the right temperature - the thermostat's contacts will open and/or close.

The contacts may be switching the electrical supply directly. But I think it's more likely that they're controlling a relay. And the relay contacts are actually switching the power.

I can see two valve sockets - but I'm not certain what's in the second one. I've seen many different devices plugged into valve sockets - not just valves. They were a convenient way of mounting items - back in the days when there were no PCBs - and everything was attached to a metal chassis.

I think there may be a relay in the far socket. I can't see much of it. But what I can see - looks like a corroded aluminium case. I could be wrong though. Perhaps the two items are identical.

If that is the case you have to ask - "Why are there two? It could be for backup. At a time when components weren't as reliable as they are today - having a second backup device would make sense - especially to someone in the aviation industry.

Another possible reason is that a single device didn't provide a long enough delay. Using two - you could double the length of the delay. You have the initial delay - while the first device heats up. Then it delivers power to the second device. And when the second device heats up - it shuts down the power.

There aren't too many external components visible. There's a tan object below the second valve socket. It looks like a small capacitor - or thermistor. It may be connected to the switching contacts - to help reduce ware. I can only see three resistors. There's one with blue wires - on the left. And there are two more - mounted on pillars - below the board. There may be more under there.

The resistors are probably controlling the amount of current that flows through the heater / heaters. This may be necessary because the devices are not suitable for direct connection to the 12v supply. Or it could be that - by reducing the heater current - you can increases the delay. With a lower current - it would take them a bit longer to warm up.

hey thanks. i appreciate all the feedback. i bookmarked that webpage and will print it out for reference.

as a footnote, i talked to my bro about it and it seems pop did not make it himself but a friend of his (rod bean) gave it to him. some of you might remember he was a hotfootspridget racer back when it was called slolem (sp?) in the days before it became autocross. i guess many of the modifications to this car were made at his suggestion. -just a little trivia there-

thanks again
chris