<VV> Re: Dash lights & dome lights

[Frank DuVal]

>In a message dated 11/16/05 9:11:45 PM Pacific Standard Time, ronh at owt.com 
>writes:
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>>Why would the radio light make any difference?
>>RonH
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>Dashlights are on a  Negative  circuit  dimmer [ rheostat ]  voltage 
>drops...current goes up...don't ask me why.....ggg
>
>Matt Nall
>65/66/69/DB/BT
>Coos Bay, Ore.
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Matt, we are working on Corvairs here. Simple 50's and 60's style dash 
lighting. All the dash lights are grounded at the bulbs. +12 volts goes 
to the headlight switch and the dimmer rheostat adds variable resistance 
to the positive wire going to the dash light bulbs. There is no dimmer 
in the negative (ground) wire in the dash light circuit.

As Jim B. says, the dome light circuit is where the bulb has +12 volts 
on it at all times and the switches ground the negative wire  to 
complete the circuit.

Both of these actions (dimming and dome switch) occur  at the physical  
location of the front of the headlight switch. But they are two 
different circuits with no intentional cross wiring.

Also, if the aftermarket radio has a dash light wire you CAN connect it 
to the Corvair dash light wire, typically gray. This will allow the 
radio dash lights to dim just like the factory radio. Always worked for 
me. But this wire is rare to find on cheap radios...

P.S. on dash light rheostat circuits the voltage at the bulb goes down, 
the current goes down and the light output goes down. All three 
measurements work together, not opposite. If current goes up in a 
filament bulb, the bulb gets brighter. Ohms Law has not been repealed.

Frank DuVal