6V SLA Dropping resistor for a 5VDC Filament Supply - diyAudio
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Old 29th January 2012, 06:32 PM   #1
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Default 6V SLA Dropping resistor for a 5VDC Filament Supply

I'm dangerously close to finishing a 71a line stage but my DMM is suspect and giving various inconsistent values and won't measure 1% resistors accurately.

Can someone lend me a hand and tell me the approximate fixed resistor value to lower a 6v SLA to 5V for a 71a .25a filament supply? Even better would be tell me how to apply ohms law or KVL/KCL to the current scenario so that I don't have to ask such a pedestrian question again.

I know I need a new DMM but that is going to have to wait for a few weeks.

Thanks!
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Old 29th January 2012, 07:02 PM   #2
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Number of volts to be dropped divided by the current.

Although what you really need is a low dropout regulator. Using a resistor will give you no overhead when the battery starts to lose voltage.
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Old 29th January 2012, 07:08 PM   #3
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So....1v/.25a=~4ohms?
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Old 29th January 2012, 07:45 PM   #4
DF96 is offline DF96  England
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Yes, Ohm's law.
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