Just what I was looking for...

[Chris Thauberger]

Remember this...

[Side-Oilers]

Cool find! 
I think they hooked one of those up to my grandfather when he was in the hospital 50 years ago.

[J_Speegle]

Yes - use to be a guy that brought one for sale to the big local swap meet every year. Think he finally sold it a few years back. With the electronics available today wonder how much of a challenge it would be to set it up to play a loop that would produce an ongoing signal without being hooked  up to a car.

Can think of a couple of people that have one or more in their displays and on shelves

[KR500]

My shop had one of these. Tossed it out many a years ago. Still have a big Sun 1115 though.
Rodney

[Bigfoot]

Cool find! 
I think they hooked one of those up to my grandfather when he was in the hospital 50 years ago.

[Steve McDonald Formally known as Mcdonas]

I think you use that to check the Flux Capacitor 

[gt350shelb]

yep threw one out about 1995