Voltage Reducer

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Jun 30, 2003 | 11:43 PM

MercM47

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Senior User

Joined: Jun 2003

Posts: 136

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Voltage Reducer

Two questions:

1) Guage Reducers

Would 12 volts still be traveling though the guages if the voltage reducers are placed between the guage and the senders (ie. Runtz)?

Why not place a voltage reducer between the ignition switch and the feed in to the guages (except the ammeter) instead.

2) Coil Ballast

I cant seem to find any ratings as to their output. The new one I bought only gave 5.4 volts. Does anyhone have any recommendations as to what a good model would be to get.

Thanks Again....

Jul 1, 2003 | 04:02 PM

johann5

Senior User

Joined: Aug 2001

Posts: 126

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From: Northwest

Voltage Reducer

Without the reducers, you'd have 12V across the guage and sender, allowing a certain amount of current to flow through both. Too much current will damage them. With the reducer you have 12V across the guage, reducer and sender and as a result you have less current. In fact, I came up with 30 Ohms to reduce the current to the same amount I'd have with 6V and no reducer. Exact value isn't critical as the guages will work without reducers, but might not last too long. You need seperate reducers for each guage so they won't interact. An alternate is to buy or build a single 6V power supply and connect it to all three guages. That's how modern cars work.
I measured my coil resistance and bought a ballast resistor to match. With this, you should have 6V across the resistor and 6V across the coil. If your 5.4V is across your coil, you could go to a slightly smaller resistor. If it seems to run okay, I doubt being slightly low matters.
Johann