How can I test these old car clocks?

[elliott194]

Hello - this seems quite a dumb question but I hope someone here won’t mind helping me out? I bought some old car clocks at auction. I know very little about electrics! There are two types - one type has a single wire coming out, the other type has three wires coming out. Ok, two wires would make sense to me - positive and negative to a DC source, but one and three wires? Can anyone tell me how to test them please? I attached some pics to explain what I mean. Thanks!

 

[Strima]

Any pictures of the fronts and what/make/model of clocks are they?

 

[westward10]

I suspect one has a lamp to illuminate it.

 

[telectrix]

I suspect one has a lamp to illuminate it.

makes sense. 1 wire for the clock +ve permanent, 1 for the light +ve off the sidelight or dash light circuit. 1 for -ve.

 

[elliott194]

Any pictures of the fronts and what/make/model of clocks are they?

Hi Strima. Two are British - one Jaeger, one Smiths. One is a Kienzle - German I guess

 

[telectrix]

some may be 6volt.

 

[elliott194]

some may be 6volt.

Thanks. So can anyone tell me how I can test them? The clock with the single wire - Is the single wire a positive? Is the clock grounded through it’s metal body?

 

[westward10]

You would need to know the age of the clock. I believe positive earth vehicles ceased in the mid 50s in the US. I would initially try 6v with negative to the body and positive to the wire.

 

[elliott194]

You would need to know the age of the clock. I believe positive earth vehicles ceased in the mid 50s in the US. I would initially try 6v with negative to the body and positive to the wire.

Thanks Westward

These are actually British clocks, I got them in the UK. One maybe German. Not sure if that makes a difference

As far as testing them goes, is using a power probe a good idea?

 

[DPG]

Not sure if you ever sorted this, but as Westward says try 6VDC first. I would also test from a current limited power supply rather than straight from a battery.

 

[EricMark]

From memory they were clockwork, and the electric wound them up, they were only powered from the ignition circuit. Also some were battery powered, the wiring was for panel lights only, back in 1950's it was regular to remove battery so clock designed to retain time. As to pos or neg earth in the main it did not matter, but I started in trade around 1968 and there was a mixture and it was regular job to convert cars from pos to neg earth so a car radio could be fitted, never remember a problem with the clock.

As to voltage most were lit, so remove bulb and see voltage of bulb, only 6 volt stuff I found was WWII ex USA wagons, Mack, I would not expect to find a 6 volt clock, Austin Ruby was 6 volt but cars of that age did not have clocks.

Most British car clocks were Smiths.