At 08:36 PM 11/22/97 -0500, you wrote:
>Folks,
> I hate to burst your bubble, but the zener application for the lamps
>will not avoid the use of the voltage-dropping resistor. The difference
>between the car's operating voltage, i.e., about 13 volts, and the zener
>voltage will have to be dropped across some device, i.e., a resistor, in the
>circuit. In reality, the current through the zener diode itself will cause an
>even greater amount of power to be dissipated by the dropping resistor. Sorry
>about that.
> As another poster already said, a readily available voltage regulator
>chip is a better device to use than a zener for the regulated 10 volts.
>
Hi Bud.
It's been a while since I had anything to do with zeners and I do understand
the point you make. That being said however I believe the goal was to clamp
the voltage at a maximum predetermined level (the zener voltage) to prevent
the low voltage lamps seeing the full system voltage but still allowing for
some adjustment. I think a resistor of the appropriate size and power
rating could be safely installed to handle the excess. I was just trying to
dissuade someone from installing 7.5 volt lamps then putting a 1/2 watt
resistor they picked up at RS in series to drop the extra 3 or 4 volts.
Cheers,
Ross MacPherson
1947 MG-TC 3528
1966 MGB-GT
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