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Old 10th Jul 2018, 2:49 pm   #5
russell_w_b
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Default Re: Info. on 'phone requested

Quote:
but what voltage should I use? 50 v.d.c.?
Use 12V d.c., Al - 50V is what is present before the loop is made, and the voltage across the instrument then drops to (typically) 12V. Don't apply a constant 50V across it! As said, the line voltage is sufficient to power telephone memories using CMOS without the need for an external supply.
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