Win At Team Racing: Turn your Vtx on and off with your beeper transistor

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Team racing is starting to require a way to turn your Vtx on/off on demand. Moving channels off to a graveyard frequency isn’t the best solution and still tosses a ton of noise throughout the band. In individual racing it would be great to be able to turn your Vtx off when you crash, especially if you crash near the pilot line.

So here is a method to use the beeper transistor to turn the power on and off.  And a transistor swap if the one on your FC can’t source enough current without burning up.


The two boards I had were both borderline to be able to support a Unify Race at 25mW, so I did a transistor swap.

MATEK411RX swapped 100ma bias transistor to ALPHA AND OMEGA SEMICONDUCTOR: AO3418
Good part for this because the gate voltage can be switched as low as 2.5V.

CLRACINGF4 swapped 200ma transitor to DIODES INCORPORATED: ZXTN25020DFHTA
Running the VTX at 25mW at 9V it was drawing about 200ma. At 200mW it was ~300ma.

Running your VTX at 12V or battery voltage will drop down the needed current and you might be able to get away without a swap.  Post what FC you are using and what transistor is on there!


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