I want to make an amplified PTT so I can use it with one of my boutique radios for which premade PTT adapters do not exist.  I have several PTT both oem 3M (peltor) as well as those made by Disco32.

I have purchased a speaker mic for the radio which I intend to cut off and use as a pre-wired connector.  I have purchased a nexus U94 part and am just looking for some assistance with the amplifier circuit needed to make this all work.  Does anyone know where I can find an electronic diagram for one?  Bonus if someone knows how to make it all fit in a u94 chassis.  

Brother is electronics guru so he can help build it, but I figured it would be easier to get some info if anyone else has done this before.

Headset is peltor comtac 3.

Thanks for your assistance.

Have you reached out to disco32 to see if they had what you needed?

I've used this circuit before and it does work.

Take a look at https://www.commgearsupply.com/  they have a lot of great adapters for different radios. They may have some stuff that will work for you. U have some adapters from them for the x50 PTT system.  They do have some powered adapters that are designed for mixing systems where power is not supplied to the PTT as well.

Yes, they politely said they were too busy.

main question is what radio.

That, pun intended, will drive the interface circuit. Use a generic one at your own risk.

This is interesting, they do have a PTT + adapter solution but it is $250.  

Radio is a Tait TP3.  It uses the same interface as several other Tait handhelds.  I am assuming it has no unique circuitry needs other than the right interface.

I'm not familiar with Tait radios, but one thing to figure out is how the PTT circuit works besides the pre-amp circuit.  Some radios are simple and the switch just grounds the MIC+ wire and that keys the radio.  Others require that a certain option pin on the radio's connector be grounded, sometimes also through a resistor, to key it.  If you already have a downlead to the radio with the connector attached, there might be circuitry inside that connector that does all that, so good to make sure.