Or, relays in series with a resistor to use up the rest of the 85v. Since
the relays are pretty much a constant resistance, a regulator is not needed
anyway.
As Marv said, this is assuming the 85v has enough current capacity for the
relays.
73,
Gerald K5GW
In a message dated 7/21/2009 9:03:24 P.M. Central Daylight Time,
wc6w_amps@yahoo.com writes:
Hi Mike,
First a couple of suppositions.
1. I presume that the "cut off voltage" is negative.
&
2. It has enough extra current capability for the relays.
You can use a LM337 with a preregulator. Take a look at Linear Technology
AN-2 to see how.
or ...
you could use a Texas Instruments TL783 positive regulator run "upside
down" with it's input switched
or...
you could eschew the regulator entirely and use a (simple two transistor)
current source to feed the relay(s) -- If they're to be switched together
they could be connected in series.
73 & Good evening,
Marv WC6W
http://wc6w.50webs.com/
--- On Tue, 7/21/09, MIKE DURKIN <patriot121@msn.com> wrote:
> From: MIKE DURKIN <patriot121@msn.com>
> Subject: [Amps] (no subject)
> To: amps@contesting.com
> Date: Tuesday, July 21, 2009, 2:30 PM
>
> Hello ..
>
> Im looking for a regulator in a (TO-220) to supply 28V for
> a few relays i picked up for my P9306UL (HL-2k) evil twin
> ... they are RF61-26S.
> I was hoping some one has a selector list - or the such, so
> that i could use the 85V cut off voltage as the supply
> voltage for the Tx/Rx relays.
>
> KC7NOA
>
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