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Re: [OM] 3V power supply (was: OM 3Ti - OM 4Ti - OM 4T question)

Subject: Re: [OM] 3V power supply (was: OM 3Ti - OM 4Ti - OM 4T question)
From: Jan Steinman <jans@xxxxxxxxxxx>
Date: Tue, 15 Dec 1998 13:37:06 -0800
To Frank's circuit, I'd like to add that you SHOULD NOT neglect the output
capacitor, and you should use a tantalum, not an aluminum, electrolytic.
I'd also suggest adding a 0.1uf ceramic capacitor to the input lead, since
that one will be quite long. Put the input capacitor as close as possible
to the IC. Because I work around RF a lot, I'd also slip a ferrite bead
over each of the input leads.

The input and output capacitors supress parasitic oscillations that can
occur at arbitrary conditions. The circuit without caps may work fine on a
bench with short leads and a regulated power supply, but with long leads in
the field, maybe used near a CB radio or cell phone, or, or, or, who knows?
Oscillation could expose your camera circuitry to nearly the full input
voltage -- can you say $400 repair for want of $3 worth of parts? I thought
you could! :-)

: Jan Steinman <mailto:jans@xxxxxxxxxxx>
: 19280 Rydman Court, West Linn, OR 97068-1331 USA
: +1.503.635.3229

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