I wasn't thinking of using the 555 as a tone oscillator, but as a timer...
You could use it like an activity timer with an AND gate connecting the COS
and the power status sensor to time the beep, or just maybe extend the
hang-time by some few hundred ms on a power-fail condition. However, that
is an interesting observation you make.
Steve
----- Original Message -----
From: "Mike WA6ILQ" <[EMAIL PROTECTED]>
To: <Repeater-Builder@yahoogroups.com>
Sent: Monday, October 18, 2004 1:45 PM
Subject: Re: [Repeater-Builder] Power monitor question
>
> At 09:54 PM 10/17/04, you wrote:
>
> >Sounds like that kind of duty cycle would just help the battery run down
> >more quickly. You might consider that type of automatic signal may not
be
> >appropriate for the service. Maybe you just need a beep after repeater
> >activity? Maybe something with a 555 timer could be built up?
>
> Please don't use a 555 - they output square waves ....
> which sounds bad and if the TX audio filtering / deviation
> control isn't what it should be they will cause adjacent
> channel interference.
>
> A simple sine wave audio oscillator is not that difficult - a
> transistor, a audio transformer, and a few resistors and
> capacitors.
>
> In my initial response I didn't suggest keying the TX PL
> encoder simply because that may already be in use, and
> using it for a power fail alert requires hooking some kind
> of an alarm to a PL decoder somewhere.
>
> My offer to engineer a real solution still stands - just get
> me a RICK manual or a copy.
>
> Mike WA6ILQ
>
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>
>
>
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