Required Parts

Parts list(Edit)

Simple parts are required to make the controller work:

  • Raspberry Pi B, B+, B2 or Pi 3
  • Power supply with micro USB connector (either from 240V or 12V depending on the application.
  • Sound Fob. These have to be a GENUINE CM108, 109 or 119 Fob. Cheap eBay Chinese knockoffs will not work with current drivers.
  • The following discrete components:
    • 1 1n914 Diode
    • 1 10k resistor
    • 1 NPN transistor (value non critical, but a BC547 suffices)
    • 1 500k Trimpot.

To use the genuine dongle skip down to Modifying the Fob. However the new Channel drivers (obtainable from the Main Setup Menu do not require any fob modification).

Updated Parts List(Edit)

As this is a rolling project, things are bound to change. We are proud to announce that the chan_simpleusb and chan_usbradio drivers have been modified to work in conjunction with the Raspberry pi and cheap chinese sound cards.

  • Power supply
  • Any of the usb sound fobs available on the internet
    • 1 1n914 Diode
    • 1 10k resistor
    • 1 NPN transistor (value non critical, but a BC547 suffices)
    • 1 500k Trimpot.
    • 1 100k resistor

To see how the Raspberry Pi is wired using cheap chinese dongles see Wiring to a radio

Modifying the Fob(Edit)

To get audio into and out of the node, plus get some signals of interest to and from the radio we need to modify the sound fob.

Only a GENUINE CM108, 109 or 119 IC will work. The cheap chinese crap will not work. There is hope for the cheap Chinese Crap, see below.

From left to right, a pair of real CM119 Audio fobs from syba. (available from ebay, one link example http://www.ebay.com.au/itm/361142822927 What I am using.

The middle two, even though they report as CM108, are not CM108, just cheap copy crap. Even if there is gpio pins, you cannot get to them. Do not buy these, even though they are cheap at even $1.00each free postage.

The last one, even though sold as a 7 channel surround sound CM108 fob from dxzone is crap and does not even report as a CM108. Useless.

BUY A DECENT FOB

Onto building it. Crack open the case (slight pressure in a vise will do it).

Two tracks need cutting, 1 capacitor will need removing and a couple of grooves will need to be cut into the circuit board to allow wiring from the other side.

Be careful not to break one track while cutting the groves, the rest it does not matter as they are linked earths anyway.

The trickiest part of the build. you need to solder (with a piece of sheathing over the lead) to the pins on the IC as pictured. Then bend the leads with sheathing through the groves. The reason we need sheathing is because of the exposed earth cuts in the board.

We cut the groves so the unit will fit back into its case.

Clip the unit back into its case so the pressure of the case stops you from ripping the leads off the IC or worse...

Solder the free leg of the diode to the pad closest to the side of the board where the capacitor was removed.

Get the NPN transistor, solder the collector to the tip of the purple socket, solder the base lead to the free end of the resistor, and solder the emitter to the square earth pad beside the crystal. push the whole plot down below the height of the sockets so the case clips together again.

The 500k pot needs to be put in the audio line from the receiver to the Mic socket, this can be done inline or in the radio itself. what we are trying to achieve here is a high impedance input with a voltage divider for the levels on the mic socket. We are amateurs a picture should not need to be drawn of this. One side of the pot to the receivers audio, the other side to earth and the centre pin to the audio fob.

This should give us a neat and tidy audio interface between radio and Pi.

For those feeling brave, there is a voltage divider that has been used on most radios with great success, using the software to modify the levels. Lift the leg of the ring of the pink connector, closest to the side of the board. cut the tag off the bottom and bend whats left under the connector body for security. slide a little knife in underneath and cut the track between the two sides. Now solder a 470k smd resistor between the pad and where the leg has been folded. then install a 68k resistor between the pad and earth..... Good luck. it is doable though

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