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jamesneely
Joined: 24 Mar 2009
Posts: 6
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 Posted: Tue Mar 24, 2009 1:20 pm Post subject: isolation circuit |
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(Please excuse the double post. I also posted this on the aeroelectric list)
I have a flightline fl-760 and the manual says that both mikes go hot on transmit. That doesn't seem a like a great idea, particularly in a noisy cockpit. They mention an optional isolation relay board, but apparently they never did produce it, so I have to make up my own.
The problem is that while I can solder just fine, I suck at designing circuits. Has anyone made one of these boards, or has a schematic that I can work from? or any source for buying such beast?
Here's the diagram provided by Flightline:
thanx,
James
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douglist(at)macnauchtan.c
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| Posted: Tue Mar 24, 2009 2:48 pm Post subject: isolation circuit |
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At 14:20 -0700 3/24/09, jamesneely wrote:
| Quote: | I have a flightline fl-760 and the manual says that both mikes go
hot on transmit. That doesn't seem a like a great idea, particularly
in a noisy cockpit. They mention an optional isolation relay board,
but apparently they never did produce it, so I have to make up my
own.
The problem is that while I can solder just fine, I suck at
designing circuits. Has anyone made one of these boards, or has a
schematic that I can work from? or any source for buying such beast?
Here's the diagram provided by Flightline:
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Two double pole relays suitable for the 12 or 24 volt aircraft power.
Power coils from fused aircraft circuit and return the coils through
the tip pins of the two push to talk jacks.
Connect mike audio inputs 1 and 2 through one pair of relay contacts
to the two mike audio inputs to the radio. You could use only one of
the inputs but there might be a problem if both talk switches are
simultaneously activated.
Connect the PTT radio pin through the other relay poles so that it is
grounded whenever either relay is activated.
Or. . .
If you use voice activated intercom those features are probably built
into it. Just wire the aircraft for a single mike output from the
intercom.
Or. . .
Some microphones, mostly older ones, use a double pole switch so that
the mike audio is only present when its own talk switch is pushed.
They're terrible for use with an intercom.
--
--> From the U S of A, the only socialist country that refuses to admit it. <--
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