Everything should be made as simple as possible, but not simpler

By Dan Romanchik, KB6NU

"Everything should be made as simple as possible, but not simpler" is a quote attributed to Albert Einstein (https://quotationcelebration.wordpress.com/2017/01/07/everything-should-be-made-as-simple-as-possible-but-not-simpler-albert-einstein/comment-page-1/). Here's one way to apply this principle in amateur radio, specifically to code practice oscillators.

A week ago, my friend, Paul emailed me:

“I am planning on teaching a two-hour introduction to Morse code to 14 girls ages 8 to 9 [[Paul's granddaughteris a Girl Scout.]]. I plan on having the girls build a code practice device. I need your help in selecting a low cost buzzer and battery holder. Please take a look around and see would you can find. I would like to limit the power to one or two AA batteries.”

I replied that I'd be happy to help him with the demonstration, and offered the following advice:

“A while back, I built the QRPGuys’ K7QO Code Practice Oscillator (https://qrpguys.com/k7qo-code-practice-oscillator). It uses a CR2032 coin battery.

“Unfortunately, they don’t sell it anymore, but the assembly manual is still online (https://qrpguys.com/wp-content/uploads/2017/03/cpo_assy_012616.pdf). The assembly manual doesn’t call out specific parts, but here are some Amazon SKUs:

·      B00J4BK0NS, Black 3V Electromagnetic Type Piezo Buzzer, 20 pcs/$6.58

·      B06XF3K4NP, Coin Cell Button Battery Holder, 30 pcs/$9

·      B008SNZUYC, 3 Pin PCB Mount Female 3.5mm Stereo Jack, 10 pcs/$5.40

·      B071RMD6FD, 1/8" 3.5mm Stereo Male Connector, 10 pcs/$7

“Batteries are available at the dollar store for about 30 cents each. So, you could do the whole thing for less than $5 for sure, even with a printed circuit board, which I would suggest that we do. Heck, if you ask nicely, the QRPGuys might even give us the artwork, or even better, have some boards still in stock. Even if they have neither, you should be able to get the boards in plenty of time.”

Later that day, Paul replied:

Thanks, Dan, for the information and making yourself available to help. I am just going to use a buzzer, key, and battery. The buzzer has a frequency of 400 Hz.

·      https://www.xump.com/science/Buzzer-Leads15V.cfm

·      https://www.xump.com/science/ContactKeySwitch.cfm

·      https://www.xump.com/science/Single-AA-Battery-Holder.cfm

And this morning, he sent me this photo, noting, “FYI. Also sounds great.”

I think that this is as good an example of "Everything should be made as simple as possible, but not simpler" as there can be. I've volunteered to help Paul with his class. That will be fun, too.

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