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Old 20th January 2003, 11:13 AM   #1
Ralph is offline Ralph  Netherlands
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Default Lowering 5.4V to 5.0V

My trafo gives 5.4V AC for my tube heaters. I want to lower this to 5.0V. What is the best way to do this?


Ralph
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Old 20th January 2003, 11:28 AM   #2
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Won't the voltage be lower with a load? or is this with a load? also, mains voltage changes... so, if you lower the voltage, somedays you may only have 4.5volts..
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Old 20th January 2003, 12:11 PM   #3
dhaen is offline dhaen  Europe
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Ralph,

You could put in a series resisitor.
Since R=V/I, then at 2A, you'd need 0.2 ohms to drop 0.4 volts.

Or, you could decide not to bother. Take a look at your mains supply from time to time. If it generally goes down, but not up, there's no problem.

Another point is to measure the voltage atually on the valve pins. You'd be surprised at how much voltage is dropped through wiring and connectors.

How's progress? Or are you getting fed up with people keep asking?

Cheers,
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Old 20th January 2003, 12:32 PM   #4
Ralph is offline Ralph  Netherlands
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I measure 5.37V AC with load on the pins of the tube. Mains voltage is fairly constant at 234V during the day.

John, progress is slow, I've been ill the last days and just getting better. With the series resistor, do you mean a voltage devider, of just one simple 0.2 Ohm resistor in series with the circuit?
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Old 20th January 2003, 12:37 PM   #5
dhaen is offline dhaen  Europe
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Ralph,

Just a single series resistor will be fine.

Get well

Cheers,
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