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Metering options for PSU


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Hi  ;D

I am learning the basics at the moment and want to build a power supply from scratch to get going. I've settled on a dual linear regulated supply based on LM317 & LM338 voltage controllers.

As this supply offers continuously variable DC output it would be good to add a voltmeter to the circuit, though perhaps a simpler solution would be to replace the pots with a range of selectable resistors to give 1.5, 3, 6, 9 and 12 volts.

I've found a 30v moving coil meter that is affordable but the impedance is very low(57 Ohms) and it has occured to me that strapping this coil over the output of my supply would cause upto 400mA to flow through the coil which is too much of the 1.5amp current that it supplies!

I've attached the schematic that i have so far, If anyone can advise the best solution or any general thoughts for this project i'd be most gratefull!

Thanks

post-25699-14279143190759_thumb.jpg

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