Touch key prototype for KX2

More details in the coming days.

73 Chris

3 Likes

The Touch Key paddle goes back to a suggestion from M0UKD. I chose the capacitor C1 with 3.3nF and thus slightly increased the sensitivity.

During my first attempts, there were no problems with HF interference at 40m / 20m.

The supply of 5V-1.8V and approx. 1mA for both sensors can be easily taken from the front socket of the KX2.

Otherwise you can use a button cell. I have provided a super capacitor, so that the circuit turns off automatically. At the beginning briefly charge the paddle should work for 20 minutes or so.

73 Chris


2 Likes

Nice! In your schematic above, you have two output lines labelled “dash”. I’m assuming one should be “dot”?

1 Like

Thanks for the hint. I only drew the “dot” part of the whole circuit.

The upper arrow goes to the 3.3V connection of the second IC, the lower one to the drain of the second MosFET. Both generate the dash signal.

73 Chris

1 Like