A Battery-operated transmitter with three large colored buttons

This is the first hand-held RF Transmitter I made. The motive was prompted by discontinuing the Smoke Transmitter.

This is the inside. The transmitter module on the beige board was re-cycled from a surplus moisture detector. It includes a loop antenna.

Here is the circuit diagram. No current flows until a button is pressed, since the negative line is open. During operation the FET is closed by a voltage generated by rectifying a PWM output.

Here is one version of the code. It gets changed sometimes.