[Dana, N1OFZ]

I’m putting together the parts I’ve accumulated and have a question. I have the generic 7.1 channel usb sound card and the easy digi interface. I cut a stereo audio cable in half to make the connections between the usb sound card and the audio transformers on the easy digi. Do I wire the tip and ring together to make it mono? Or do I just use the tip and sleeve and don’t worry about the right channel?

I just want to make sure there are no audio level or channel issues down the road.

Thanks!

[Aaron, N3MBH]

For the mic input on your sound card that is your RX side. That would be mono So tip (signal) and sleeve (ground). You can probably wire the ring in the with sleeve (ground) effectively making it a mono connector.

For the output of the sound card, this is your TX side. That is usually stereo on the card. You can use the tip and sleeve (left channel) or ring and sleeve (right channel).

As long as you got the EasyDigi with the optocoupler, you should be able to wire that up to operate the PTT like on your TX radio. As for the RX radio, you would have to rig up your own control circuit to operate the COS line. I discourage the use of vox for detecting squelch on the RX radio.

Hope that helps.

73,
Aaron – N3MBH / WRFV871

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[Dana, N1OFZ]

Yes I have the EasyDigi with the optocoupler. I’ll wire both with tip and sleeve and ignore the ring on both sides of the sound card.

As far as the receiver, I’m not sure what radio I’m going to use yet but I understand what you are saying in regards to the circuit for the COS line.

Thanks!

[Dana, N1OFZ]

Aaron, what do you think of using a Motorola GM300 as a receiver? It already has a COS line, just need to drop the voltage a little.

[Damon, N0FON]

I am going to use an M1250 and do the same thing. what is the voltage on the COS line out of the radio? On my Micor repeater I had to do a lot of voltage adjustments.

[Dana, N1OFZ]

I picked up a couple of them and they are on the way so I can’t verify for sure but from what I have read it’s 5V. My understanding is I just need to drop it to around 3 as to not fry the pi.

[Aaron, N3MBH]

At 5v I would just recommend building a simple optocoupler circuit. If it is 5V when active, you build your circuit to light up the LED on the optocoupler with proper resistance in series for your needs. On the phototransistor side of the optocoupler you will just wire that up to pull the COS GPIO pin to ground (low) when the LED is lit. Be sure to add in a pull up resister to pull the COS GPIO pin up to 3.3 volts when the LED is off. This will prevent the COS input pin from floating and causing erratic behavior.

73,
Aaron – N3MBH / WRFV871

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[Dana, N1OFZ]

I can configure COS to be high or low. Which do you think is cleaner/easier given my setup with the EasyDigi? I’m looking forward to hopefully getting my hands on a OpenRepeater hardware interface the next time they are available. It will surely simplify things!

I also found my original question would have answered itself had I waited until I had OpenRepeater running. In case someone is reading this in the future, you can select either right or left from the audio device input on the ports page. 🙂

[Aaron, N3MBH]

For a simple COS circuit, I would use an optocoupler On the RPI (photo transistor side) you would just make the active state ground the COS GPIO pin then make sure you include a pull up resister to pull the GPIO pin up to 3.3v when the optocoupler is inactive.

On the radio side you would simply need whatever resistor to operate the LED in the optocoupler. So when your COS is active the radio pin goes high activating the LED in the Optocoupler and making the COS GPIO pin go to ground (active low). This is the way v1.1 is. It is active low, but we are givng the option to make it active high in the next release.

As for the interface board. There will be an upcoming group order in April. Keep an eye on the site or social media for updates as I will be posting soon.

73,
Aaron – N3MBH / WRFV871

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