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Homebrew touch paddle for less then 10€

I would like to introduce you to my latest homebrew project. A contactless cw paddle for less than 10 euros.

The circuit requires two contacts each, which are connected by the skin resistance. Since I hold the key in my hand while keying on the summit and touch one contact, touching the second contact is sufficient. If you have very dry skin, some saliva or a higher summit will help. :sweat_smile:

I get the operating voltage of the circuit from the trx, because the current devices have a switching voltage of 3.3-5V at the key input. This voltage switches the transistor through when touched and the symbol is sent. The capacitor C7 (why not C3 :face_with_raised_eyebrow:) holds the charge even when keying and R1C1 / R2C2 block the RF.

73 Chris


13 Likes

Very clever Chris. I would like to try one of those please. Do you have an online shop etc.
Best 73

Unfortunately nothing like that.
73 Chris

1 Like

I have built my version of this little critter and it works!

I will take it to the summits and test it in the field. I have my doubts that it will key reliable in cold or rainy weather, but let’s see! I will report back. It definitely needs some spit on the finger tips to key accurately.

The big advantage of this design is that it runs without a battery. One item less that can fail. It is also light weight. If I stick with this keyer I would build another one with smaller resistors (the 22MOhm are 5W), eventually with SMD components to see how light it can get.

Nice project!

73 Heinz

2 Likes

Hello Chris,
Thank you for sharing the circurit-design. Now I Have build my own touch-
paddel, work’s fine on every rig and keyer I have. It is the first build and I try
to build a premium version soon. It’s ideal for portabel OP’s and weight is
only 17-18 gramms. I will do some heavy weather testing(Rain,snow and
cold)to see, if it works under bad conditions. But up to now it’s perfekt for
me, without a Battery that’s the best…

73 Thomas DD4EA




4 Likes