Hi Tim,
As Ron mentioned, yes with zero pressure, it’s 10s of Meg ohms. The chart shows the results of measurements and it looks like the lightest pressure measured was about 100g which resulted in around 6.9 k ohm. As you can see, the slope is very steep, so as the pressure gets lighter, the resistance rises rapidly. There are practical measurement difficulties at very light pressures and very high resistance which would be why they stopped at 100g.
73
David
VK3IL
Ok David. Thanks. That is what I thought but I just had to make sure. AND like I said before I think it is the best SOTA keyer ever!
73
Tim - K5DEZ
Hi all,
Has anyone used this paddle at speeds up to 30-40 wpm ?
73 Patrick
Sending 20-22 wpm is my comfortable speed for SOTA activations and it works very well. I can copy short bursts (SOTA QSO’s) up to 25 or so but 30 wpm is a bit above my “Pay Grade”… but I can send my callsign at that speed with no problem. I am relatively sure it will work at the higher speeds also once up get use to how the paddles operates and get the sensitivity the way you like it. The sensitivity can be adjusted by changing the pull-up resistor.
Tim - K5DEZ
Somebody have tested it with the QCX + or mini ?
73, nicolas
Hi Nicolas,
Yes, just tried mine with the QCX Mini and it works fine.
Cheers,
Glenn VK3YY.
Hi Glenn,
Thank you very much for the “real time” test !!!
So I will pass an order to the PCB fabrication. The minimum is 5 pieces. If somebody needs one ???
HNY,
73, Nicolas
Re performance curve for sensor.
The most common application is measuring if there is a bum on a car seat. 100 g is way less than even the littlest bum. Hence no point in going lower
73
Ron
VK3AFW
Hi Nicolas,
Me… Would be interested to try this solution !
Let me know…
73 Patrick TK5EP
OK je t’en garde un …
73, Nicolas
Merci,
Où as-tu trouvé les capteurs ?
73 EP
je compte les commander en chine : 1,60€ par capteur. Tu cherches chez ali : RP-C18.3-ST
Tu es interessé pour une commande groupée ?
Andy,
Quantum tunnelling seems to be the dominant mechanism in these sensors, according to Wikipedia.
73
Ron
Hi folks, I received my boards from Oshpark - US$16.60 for three high quality boards, free postage and quick service.
I built it this afternoon and all works FB so I have now shared the design on Oshpark. Here’s a link if you wish to use this service.
https://oshpark.com/shared_projects/mdpjKbGi
It’s an excellent design, I can’t wait to try it on a summit this weekend! Thanks David!
73
Geoff ZL3GA
Just an update to this - the boards on OSHPARK are V1.1, David has since released some new designs which give you flexibility of form-factor and also utilise a larger diode - those RB530sm-30’s were TINY!
Check out his wordpress site for details.
Also, if you are in ZL/VK, Peter VK3PF is looking at doing a kit-run.
73
Geoff ZL3GA
Hi all,
As Geoff has mentioned, I AM doing a kit run. I am still awaiting deliveries of items. Some of the pressure sensor pads are on the “slow boat” from China, but I have limited stock on hand to start kitting as soon as a delivery arrives late next week (expected).
Once I have all the goods, I will first deal with the EoIs already collected via the OZSOTA Group and will make an announcement after those orders have been sent to recipients.
Due to MOQs, I expect to have a total of 50 kits available, provided all the parts arrive. I have 25 of the V1.2 and 25 of the V1.2B boards already delivered. I could have ordered more components, but thought that 50 should satisfy likely demand.
As Geoff has stated, check David’s blog for the details of the boards.
Preference will go to VK & ZL amateurs in the first instance. Delivery times of sensors will determine when kits are available to send out, but I expect the first 20 kits to be ready in about 2 weeks. The initial 20 kits have homes, subject to funds being received. I have not yet determined the cost of the kit, but I will be looking to only recover my costs with a small rounding up to the nearest dollar.
Regards,
Peter VK3PF
Thanks for posting the link Geoff @ZL3GA and most importantly to David @VK3IL for his time on producing this project and making it available to all.
My 3 boards arrived today ordered on the 4th March costing £12 posted to the UK just need to source the components.
I have just finished mine… The diodes are very small to solder !!! I lose one !!
With the given values, only the DOT is working with my IC-706 … but DOT and DASH are working well with my QCX-mini which is the goal of this keyer. I had only some 40uF capacitors …it’is perhaps why when press the two paddles together I have only repetitive DOT and no DASH (no iambic behavior)
Funny keyer, thank you David !!!
So I like my pressure paddle enough to build a second one, this time the V1.2B version that’s 10cm long and (hopefully) easier to hold in the hand. ALLPCB is running a promo where you can order one small (<0.015m^2) set of boards a month for free and so I figured why not. Unfortunately, I’m having a hard time finding any MMBF4117 JFETs. Has anyone discovered an acceptible substitute for the current limiting JFET?
Cheers,
John VA7JBE
