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General Interest & Information / The "Secret Life Of Radio"
« Last post by G0KZZ on Today at 07:50:23 PM »
Many years ago I remember watching this episode and thinking how fascinating it was. Fast forward LOTS of years and I still haven't changed my mind.

Apart from which I love spark transmitters bd

https://www.youtube.com/watch?v=2roG4jIjvEk

 ::)
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Homebrew Morse Keys / Re: Capacitive Touch Double Paddle
« Last post by foggycoder on Today at 12:42:49 PM »
Okay - I've ordered a couple of Arduino-compatible rain sensors. I should be able to use the output to latch a relay. Thinking Cap on.

While I wait for them to arrive, I'll have a play around with vero board.
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Homebrew Morse Keys / Re: Capacitive Touch Double Paddle
« Last post by foggycoder on Today at 09:12:52 AM »
Thanks, G0KZZ. There are some excellent ideas there.

There never seems to be any shortage of things to do. Electronics is just one of several bottomless pits!
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General Interest & Information / Re: Portishead Radio - a new book
« Last post by G0KZZ on September 27, 2020, 10:32:21 PM »
Forgot to say Larry, the book turned up safe and sound the other day.

I love some of those photographs, they really make the book. I doubt it would have been half as interesting otherwise.

Good stuff! bd

73, Mark...
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Homebrew Morse Keys / Re: Capacitive Touch Double Paddle
« Last post by G0KZZ on September 27, 2020, 10:19:37 PM »
UPDATE

The Touch Paddle (my electronics guru is not convinced it's a capacitive touch paddle) triggers my K-16 keyer but only as a single paddle. When both paddles are touched at the same time (squeeze mode) the result is largely random dits and dahs.

Also, the output does not trigger my Morserino. I tried a Darlington Pair on both sides but, whilst the DP worked on the breadboard, I couldn't get it to work on the key itself.

I suppose one can't expect too much from such crude materials. I'll therefore start work on a version with relays instead of transistors. But this has been fun so far.

I didn't want to say anything before, but your 'guru' is correct.

Touch paddles, or rather  capacitive touch sensors tend to use an HF oscillator to 'drive' the sensor. When you touch the sensor, or even come close to it, some of the energy will be 'robbed' by your fingers/body, causing a drop in voltage on the sensor. This voltage drop is detected and used to trigger the output from the sensor.

Some use another system whereby the sensor pad forms part of a tuned circuit, and the act of touching or getting close to the sensor will alter the frequency of the oscillation, wherein the appropriate circuitry will detect this shift and will again make some change to the output of the sensor unit.

What you have assembled there is more like conduction sensor rather than capacitive. When you touch the sensor plates on your circuit you will be acting as either an antenna, or as a load. Any electrostatic mains hum present will pass through your body, and through the transistors attached to the plates. You could think of the transistors as being open loop amplifiers, so as soon as you touch the plates the electrostatic hum will switch the transistors on and off.

Whether the 'hum' or 'noise' is coming from the unit, the mains, or some other signal being picked up by your body doesn't matter, the effect will be the same. If you ground your free hand to say the case on your keyer you may find it stops working.

In the absence of a true capacitive touch sensor it is still possible to make a simple conduction sensor that will be more reliable than the version you have there, and it would allow for Iambic keying.

We used to use designs like this many years ago for assorted touch switching applications. All you need is some Vero board (copper matrix board), a couple of transistors, and a few resistors.

Make two 'paddles' from the matrix board, with the tracks running horizontally. Connect together alternate tracks so that say, if the strip of Vero was six tracks wide you would end up with two lots of three tracks intermeshed with each other.

On each of your Vero 'paddles' connect one set of strips to the positive terminal of a battery, and on each paddle connect the other set of strips to the base of your NPN transistors via a resistor (this is simply to prevent damage to the transistors in the event of a dead short across the strips).

The emitters of the transistors are tied together like on your version. So now, if you touch either paddle the current from the battery will flow through you fingertips back in to the adjacent set of strips, through the resistors, and in to the transistor bases biasing them on.

There are more 'fancy' versions of this idea, but even the simplified version given here will work fine. If you search the web for "simple liquid detector" or "simple rain detector" you can find similar circuits. The idea being that rain, or any conductive liquid falling between the tracks will switch the transistor on.

I just had a quick look and found a "Raindrop/Snow Detector" on Amazon, and although the sensor circuit is more elaborate, the actual 'sensor' is just a slightly improved version of the matrix board one I outlined above. See here >>>https://www.amazon.co.uk/AZDelivery-Raindrop-Sensor-Module-Arduino/dp/B07CP2GX9P/ref=sr_1_1?dchild=1&keywords=Rain+drop+sensor&linkCode=gs3&qid=1601241105&sr=8-1&tag=78740e-21

If you look closely at the images you can see how the tracks inter-mesh but do not touch. Any liquid across them 'shorts' them out creating a circuit.

In fact, a pair of those Rain/Snow detector units might make for a good, cheap, touch paddle!

Hope that helps.

73, Mark...

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Homebrew Morse Keys / Re: Capacitive Touch Double Paddle
« Last post by foggycoder on September 27, 2020, 07:41:07 PM »
UPDATE

The Touch Paddle (my electronics guru is not convinced it's a capacitive touch paddle) triggers my K-16 keyer but only as a single paddle. When both paddles are touched at the same time (squeeze mode) the result is largely random dits and dahs.

Also, the output does not trigger my Morserino. I tried a Darlington Pair on both sides but, whilst the DP worked on the breadboard, I couldn't get it to work on the key itself.

I suppose one can't expect too much from such crude materials. I'll therefore start work on a version with relays instead of transistors. But this has been fun so far.
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On The Air With Morse Code / Re: 472KHz Sunday CW Net
« Last post by GM0WEZ on September 27, 2020, 06:38:22 PM »
FB Mark. Radcom had reported a conventional (not QRSS) CW activity net around 9am Sundays - unfortunately I missed it!. I will have a listen next week with SDR fed with PA0DRT mini whip and append results to this thread.

Getting a signal out is harder - I have the QRP Labs Ultimate 3S with 472kHz output filter, though that is very QRP for this band. And at present I just have a vertical so I'd need to reconfigure it as an inverted L. Which might be worth doing anyway now as winter is coming and I spend more time on the lower bands.

I have had good MW results with portable SW receiver (Sony SW7600) and a Tecsun MW loop (about a foot across) simply held near it. I don't know if it will tune to 472kHZ but I think probably not. Some homebrew might be necessary.

Canine QRM is an issue at this QTH too. We have a pug, Monty, and for some reason CW sets him off. I suppose he thinks it sounds like the doorbell.
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On The Air With Morse Code / 472KHz Sunday CW Net
« Last post by G0KZZ on September 27, 2020, 09:45:35 AM »
While in conversation with GM0WEZ the subject of a CW net of 472KHz came up. I didn't even realise this was a 'thing' so I thought I would have a go to see if I could here anything.

Because I only had short notice of this event there was not much time to set up anything efficient, so I resorted to trying a Tecsun PL-365 handheld receiver, and used the extended ferrite rod I have for it.

Guess what , it actually worked! Although there were various noises from PSU, TVs, PCs and gawd knows what else polluting the band I did manage to hear the net down there.

Readability was varying from R1 to R3 at absolute best due to all of the QRM, but I managed to catch (I think), G3FGJ, G4XIZ, and M0JXM (apologies if I misheard any of the calls).

In order to find a clearer signal I ventured away from the house to the bottom of the garden, where I did find the QRM to be much weaker. However, a neighbours dog who is a member of the anti-CW league decided to 'jam' the signal by barking his tail off! bh

Oh well, it's a start I guess. bd

73, Mark...
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Homebrew Morse Keys / Capacitive Touch Double Paddle
« Last post by foggycoder on September 26, 2020, 01:31:55 PM »
As some of you may know, I'm a great admirer of the QSK llc, TP-1 Touch Paddle but it's a bit expensive for me at 190 delivered.

I've been doing some experiments with transistors, partly because I'm trying to learn some electronics and partly because I had this idea to modify my CW Beacon as a touch keyer using transistors instead of relays. Almost by accident, I seem to have come up with this device (images below). It looks too simple to work at all but, amazingly, it works very well!  I've tried it out on Vail and CWCOM and it works without any adjustments to settings.

I already had the two 2N2222 general purpose transistors and the 1000 ohm resistors (they cost pence anyway). And the stereo lead cost 1 (from Kitronics). The rest of it was laying about the Man Cave (the self-adhesive copper tape is used in the garden as a not-very-effective slug repellent).

As I hope you can see, the transistor Base is connected through the resistor to the conductive pad. The Emitters are connected together and go to the earth connection on the "sleeve" of the TRS jack. The Collectors are the output: the left one goes to the "tip" of the jack (dits); the right one goes to the "ring" of the jack (dahs). The touch key jack is plugged into my Kanga K-16 keyer and that plugs into your radio or whatever else you're using to send morse.

You can tell, I'm dead chuffed - for a 1 and a very pleasant hour tinkering at my workbench, I have a very good capacitive touch double paddle.
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On The Air With Morse Code / Re: Sidetone frequency
« Last post by G0KZZ on September 25, 2020, 10:00:07 AM »
Some of the 'difficulties' might still be down to our own subconscious though.

Many years ago I got chatting with a colleague, and it turned out he had previously worked for Interpol.

He was telling me that there minimum test speed requirement was 25wpm. I said that the Amateur one was (at the time in the UK), 12wpm. I also mentioned that many would be CW op's would reach a kind of plateau in their learning and get 'stuck' at around 8-9wpm for ages before finally breaking through some hidden mental barrier.

He seemed surprised at this, but did say that their (Interpol) operators very often got stuck around 17-18wpm while learning Morse.

It struck me then that both groups had gotten 'stuck' at a speed that was say 2/3 to 3/4 of their final target.

Maybe we need to aim higher, much much higher!

Again, just another thought...

 :w:
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