[time-nuts] Parallel voltage regulators

Alan Melia alan.melia at btinternet.com
Wed Oct 24 20:11:47 EDT 2007

Hi Tom I dont think you need the resistors these are current limited and the
sense is inside the chip so the resistors dont do anything (you are thinking
of a negative feedback effect). All that happens in paralled operation is
that one may take the majority of the current til it current limits and the
rest is provided by the other. They will need heat sinking. You can get
Hi-power versions of these fixed regs as well or use one of them to drive a
big transistor (the 2N2955 PNP used to be a popular choice up to 5A) for the
series control. You may ned to lift the common leg with a diode to allow for
the e-b drop on the pass transistor if you use an NPN.
Cheers de Alan G3NYK

----- Original Message -----
From: "Tom Clifton" <kc0vsj at yahoo.com>
To: <time-nuts at febo.com>
Sent: Thursday, October 25, 2007 12:33 AM
Subject: [time-nuts] Parallel voltage regulators

> A question for those that might know (or have an
> opinion)...  I have in hand an LPRO rubidium reference
> that requires 1.7 amps at 24 volts while the oven
> warms, dropping to 500ma while it runs.
> Can I parallel three or four 7824 TO220 style 1 amp
> regulators with a quarter ohm half watt equalizing
> resistor on the output of each one?
> At maximum load there would be a quarter volt drop
> across the resistors and the LPRO is stated to be ok
> running on 16 to 32 volts.
> Tom
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