Talking House ST-1009 aux-in mod
2026-10-07_am-tx-mod

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#tech #hw #project #guide

The ST-1009 version of the Talking House AM transmitter will only play a recorded message, but it's easy to modify it to directly broadcast the aux input. This info comes courtesy of Rich Post in The Spectrum Monitor.

Note: the internal speaker will continue to play the recorded message. You might want to add a label noting this, or just disconnect the speaker. (Or figure out how to fix it then hit "send feedback" and I'll update the post!)

  1. Unplug it from the wall and open it up.
  2. Lift the chip-side leg of the capacitor labeled C221.
  3. Disconnect the aux input's blue and white1 wires from the board.
  4. Solder the blue wire to the lifted capacitor leg.

Note: the aux-in will be amplified, so use a line-level source or turn the volume down before you plug it in.

§ Misc. notes ^

  • The board with the smaller display on it has jumpers for selecting 90, 180, or 270 seconds. Mine was jumpered for 180, but it only seemed to record for 90. I never tried to record the whole 90 seconds, though.
  • The board shown in The Spectrum Monitor has an empty middle chip socket, but mine was populated with a duplicate of the main chip. Maybe each one stores 90 seconds? Removing it did not appear to affect function in any way. Let me know if you need my spare.
  • You could probably turn the recorder into a looper. I mean, it IS a looper, but like, I think you could use it like a tape loop and do fun music stuff with it. It doesn't always erase the old recording when you start a new one.
  • There's a deep gouge on my board cutting a trace and at least one bodge. I have no idea where these came from. The build quality of the entire device is slipshod the connectors aren't even on straight! so they could be from the factory.

§ Footnotes ^

  1. I'm not convinced the white wire needs to be removed; the author didn't elaborate on why he cut it. It's labeled C2, but it's a sense wire, not a second channel it detects if you have anything plugged into the aux by going open. So, by disconnecting it, you prevent the Talking House from recording with the internal microphone. If you bridge the pads where the blue and wire wires were connected, you should be able to record with the mic and aux-in simultaneously? <-|

§ See Also ^