Building the VK3IL Pressure Paddle for Amateur Radio use with CW Morse Code 

Happy to help! Thanks for watching.

I appreciate the tip. I'll make another paddle down the road and I'll forgo the flux. I'll let you know in like 6 months, lol.

I use Wirefy 3:1 heat shrink from Amazon. The piece I used to finish off the pressure paddle was 3/4" or 19.1mm. Pretty sure that's the diameter. Length was about 3 inches long. Thanks for watching!

@@CoaxAndCampstools (at first, sorry for english is not my first language.) yes, before you comment my comment, i realized diameter of heat shrink in your videos. i didn't see in ur videos. sorry for that but thanks for ur comment. i have to make or buy iambic key, and i found the pressure paddle is my taste, so i am going to make this paddle. that is the reason i am bought soldering iron, and also. thanks for your comment, hope to see you in HF. and my call is starting ds, thats from south korea. 73.

@@linearphaselowband No worries, my friend. I didn't know the diameter myself, so I was happy to dig out the key to look. It's a good intro to surface mount components. I hope to work you too, you would be my first South Korean station. 73!

@@CoaxAndCampstools this is my taste also :) thanks!!!

If I knew how to design the circuit board, I would make it fit snugly inside of 1/2 inch cpvc pipe.

I'd say the only reason the wires matter is because of the assumed "front" of the key having all the components on it, but yes it doesn't really matter. Interesting idea with using circuit board traces as the capacitive component. I'm not electrically inclined enough to know whether that could work or not. From what I remember: As to the third point, the sensors are capacitive through interdigitated conductors. The plastic enclosure has some... give to it with an air gap separating the conductive layers slightly. Pressing the key reduces the capacitance enough that the circuitry overcomes the gap. There's a word for the gap that I can't remember currently. I'll try to dig up my key and get back to you about that. If I'm wrong I'll tell you :)

@@CoaxAndCampstools - In VK3IL's blog he describes how the bias on his FET gates is operated by a voltage divider which, when his sensor is touched, drops the resistance from >10 meg ohms down to less than 20 K ohms which results in a jump in gate voltage (95% of the drain voltage) that triggers the FET to fully conduct. I have a hard time believing that the "pressure" sensors are anything more than two conductors designed in a spiral. When I take my DVM and put it's sensitivity to 200K, then touch the lead tips, the resistance drops down to say 130 K from infinite resistance. Given the length of the spiral, it is reasonable to think that the drop is proportional to the length of the spiral and how much of it is "touched" when activating the FET key switch. One could set the (open switch) voltage at the gate with two actual resistors and then trigger the gate (raise the voltage) by putting the spiral sensor in parallel with the resistor across the gate/drain if the spiral doesn't drop the resistance far enough on its own. I'm certain this would work and could be accomplished by just making the spiral out of traces and as an integral part of the circuit board. I don't have the means to design or fabricate the idea but does it really matter what causes the voltage increase at the gate? The cost of the touch paddles would be reduced by 50%. Also there is no compelling reason to design the thing with difficult tiny SMD parts, given the parts count is so low. I would recommend a TRS connector as well. I notice that Adam K6ARK's touch paddles operate on an entirely different design philosophy - sensing a change in capacitance rather than a change in resistance. I'd be interested to know if the sensors you have actually drop in resistance when pressed with a purely insulated object, like glass or plastic. If it doesn't drop, then the sensor is not sensing pressure, but is sensing your skin resistance. (I could be wrong about the sensors as I've never had a chance to play with them. As a design consideration, I think the pull-up resistors in the dit/dah inputs is about 1K for most uControllers. VK3IL uses a 470 K resistor for his source/drain bias so the drop in sensor resistance easily swamps the source/gate resistor and causes the triggering of the FET. Thanks for getting back to me. I appreciate the conversation.