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-   -   Wanted: Electrical work done on an Apollo SL15/PMA7000B (https://vansairforce.net/community/showthread.php?t=94225)

TS Flightlines 12-17-2012 08:10 AM

Surely, with all the smart guys and gals we have on VAF, we can come up with a solution. I see it as a safety thing.
Tom

Mike S 12-17-2012 09:31 AM

Quote:

Originally Posted by Kahuna (Post 726043)
I want one small light on my glare shield indicating that one of the coms is on transmit, just like the button has.

I am no electrical wizard, but it seems like you (or whoever does the actual work) could just re-direct the power from the button to the external light.

You would loose the light on the button, but you would have the glare shield light instead.

ChrisMallory 12-17-2012 12:03 PM

can you swap the pushbutton
 
If you can switch out the pushbotton on your stick with a toggle switch I have a solution for you.

I don't know of an on-off-on pushbutton. This would also work if one existed.

mscheuer 12-17-2012 12:45 PM

Caution
 
The LEDs as well as the pushbutton switchs are controlled by FPGAs with TTL control. I do not recommend bringing those signals out of the audio panel, these signals would have to be conditioned before meeting the outside world.

Mark
PS Engineering, Inc.

Quote:

Originally Posted by Mike S (Post 726079)
I am no electrical wizard, but it seems like you (or whoever does the actual work) could just re-direct the power from the button to the external light.

You would loose the light on the button, but you would have the glare shield light instead.


BobTurner 12-17-2012 12:49 PM

If you want to build a box with some relays:

1. Wire your flip-flop stick button to cause a latching relay to flip.
2. Wire that latching relay to control other relays, which will:
A. Connect your mike, PTT, and headphones alternately to the pilot inputs, or the copilot inputs, on the audio panel; and
B. drive indicator lights on the glare shield.
3. Put your audio panel into the multiplex mode, or whatever it is called (designed to let the copilot transmit on com 2 while the pilot transmits on com 1.)

Basically you are flipping yourself from pilot position to copilot position.

Edit: I see PS calls this "split mode", not multiplex.

Mark, what do you think?

PaigeHoffart 12-17-2012 04:11 PM

Quote:

Originally Posted by Kahuna (Post 726011)
Hmmm. This is an interesting thought. I assumed that the key was not only putting the com in transmit, but also the audio panel routing voice to the proper com. 2 com switches would require direct key to ground for each radio but how would the radio get the voice from the proper mic? This seems to be defeating the audio panel functionality. Im sure there are other unintended consequences of this as welll.

My audio system is a bit unique, I didn't use a commercial audio panel. You could however achieve the same effect with one relay. Your first PTT will work with the audio panel just as it does now. The second PTT will bypass it and connect the pilots mic directly to one of the radios.

12V 4PDT relays are easy to find. You can get sockets that make wiring with ring terminals easy. Route the pilot's mic wires through two poles, intercom to the NC contacts and radio to the NO contacts. Use one of the remaining poles for PTT. Radio PTT to the common, NC contact to the intercom PTT out, and ground the NO contact. Wire the Relay coil to the second PTT switch.

The downside is that if the relay fails, you could lose the ability to transmit. Solid state switching would have higher reliability, but the mechanical life of most of these relays is in excess of 20 million operations anyway.

There is also a possibility that you could run into issues with hearing your transmissions on the other radio; you could use the fourth contact to mute it if necessary.

Paige

Neal@F14 12-17-2012 04:31 PM

Quote:

Originally Posted by mscheuer (Post 726154)
The LEDs as well as the pushbutton switchs are controlled by FPGAs with TTL control. I do not recommend bringing those signals out of the audio panel, these signals would have to be conditioned before meeting the outside world.

Take the signal off the LED in the Com2 Xmit button, and send it to a one-transistor relay driver circuit. Make the 1-transistor relay circuit as small as possible to fit somewhere inside the audio panel case itself to protect it. Then send a relay-switched +12V out the back thru an unused or re-purposed rear connector pin

Here's some examples of both active-high and active-low switching circuits depending on how your FPGA drives the LEDs.
http://www.pcbheaven.com/wikipages/Transistor_Circuits/


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