A Crummy Commercial

I have blogged on this idea before in passing but it's worth repeating: when building an electronic project be sure to use a Sharpie on either the inside of the case (or on the circuit board) to record the date. Then, enter that date and as many notes as you can think of about the project into a lab notebook ! If you are like me your memory was never that good, but even if you HAD a good memory, it will probably get worse as time goes by.  With the written date it will be easy to refresh your memory on the project.  And in that notebook, remember 5 Ws and an H: An excerpt from the Kipling poem: Keep Six Honest Serving Men I keep six honest serving-men    (They taught me all I knew); Their names are What and Why and When     And How and Where and Who. source:  https://www.kiplingsociety.co.uk/poem/poems_serving.htm In other words, consider yourself a reporter trying to explain the project to someone who is unaware of this project (probably YOU in t...

Senseless Destruction but Fun: source: https://www.youtube.com/watch?v=_bdp9nk0NZk I never would have thought of this idea.  Now I have (like most experimenters) accidentally connected power backwards.  The center ground pin on a coaxial power connector was the culprit when I popped the big electrolytic in my old Koss amplified computer speakers (I should have used the wall wart !).  What an amazing stink was discovered !  Yuck, hopefully whatever gas is released doesn't cause disease :)  Now I routinely incorporate some kind of reverse polarity protection circuitry into any project. The only willful destruction of electronics that I recall participating in was using a tube tester in the Nicolet Radio Club to "supernova" the filaments of innocent vacuum tubes :)  What a waste - it got old rapidly though. Best Regards, Chuck, WB9KZY http://wb9kzy.com/ham.htm

While pursuing a favorite activity, browsing magazines, I saw this cover: It's from the March 1934 issue of Radio-Craft magazine.  And the Phonosone article is by none other than Hugo Gernsback himself ! source: https://dn760003.eu.archive.org/0/items/Radio-Craft_1934_03/Radio-Craft_1934_03.pdf If you've never heard of Hugo Gernsback before try the wiki: https://en.wikipedia.org/wiki/Hugo_Gernsback photo scanned from the November 1967 issue of Radio-Electronics magazine (page 4) by Michael Holley Swtpc6800. The phonosone itself was basically one half of a pair of headphones that were modified to provide for better bone conduction. No, I have not tried building one although the man on the cover does seem to be really happy  !  :) The inflated price of Radio-Craft : I will have to look to see if Mann's Store still has magazines for sale the next time I'm in there. Best Regards, Chuck, WB9KZY http://wb9kzy.com/ham.htm 

A fun video from Ringway Manchester: source:  https://www.youtube.com/watch?v=7y_i0RjRBr0 What caught my eye was the simple power switch used in both designs - very clever.  Good switches are expensive, bulky and attract attention.  This method of using copper tape to bridge two contacts is easy to fabricate, inexpensive and not as obvious as a commercial switch.  And it might have been possible to hide the circuitry below some cardboard with matches on top ? The Radio Shack weather radios are still available (used) on Ebay: https://www.ebay.com/itm/158073241107 There are many "bugs" on the internet - most are in the FM broadcast band but could probably be moved up in frequency fairly easily - here's a slightly more modern design: https://www.electronics-diy.com/electronic_schematic.php?id=989 there weren't any 3 volt lithium coin cells (at least not in common usage) 40 years ago. This design should fit in a matchbox :)   But it probably won't work any bett...

Mentioned on the piclist: https://archive.org/search?query=subject%3A%22Elektor%22 also this Elektor collection: https://archive.org/details/ElektorMagazine/Elektor%5Bnonlinear.ir%5D%201974-12/ Per the wiki, a Dutch based electronics magazine so they may not all be in english, however it's always possible to use translate.google.com . the elektor site has a search including old issues: www.elektormagazine.com As long as the internet lives, I will NEVER run out of magazines to look at !  :) Best Regards, Chuck, WB9KZY http://wb9kzy.com/ham.htm

I found out that Practical Wireless , a UK ham radio magazine, is available via overdrive.com, nice !   https://www.overdrive.com/media/8765740/practical-wireless In addition Overdrive still has a few 2023 issues from the now defunct CQ Amateur Radio , too. https://www.overdrive.com/media/5855264/cq-amateur-radio I mentioned Overdrive and CQ before: https://wb9kzy.blogspot.com/2024/04/cq-magazine.html Best Regards, Chuck, WB9KZY http://wb9kzy.com/ham.htm

I saw these items listed on Ebay from my favorite purveyor of miscellaneous electronic stuff: The assortment was $26.38 with tax/postage - I saw the HD-1410 keyer (don't need another one but why not ? it has the rare AC power cord) - also an Ameco CPO (don't need that either but never had one) - finally the seller mentions that they don't know what the mini blue device (upper right) is:   I KNOW, it's a DSW transceiver from Small Wonder Labs, 1st generation, the $15 on top is not a bad price either.  Depending on which band it is, I may or may not already have one :) BTW this is the same seller I got the AADE LC meter from mentioned previously: https://wb9kzy.blogspot.com/2025/10/just-because-i-could.html I suspect that I'll have to fix the DSW (and probably the keyer and CPO, too) as I did with the AADE LC meter but it'll be something to do ! update 7-7-2026:  I received the box of stuff on Monday (7-6) and will have more blog posts as I work through the stuff....

I've mentioned battery level testing before: https://wb9kzy.blogspot.com/2026/05/low-power-battery-level-circuit.html https://wb9kzy.blogspot.com/2025/01/good-old-sears.html On a recent morning the smoke detector in the basement started beeping.  The Nimh battery was down below 7.5 volts - this corresponded to just entering the BAD region of the Sears VOM: just a picture of the VOM, no test being done So I think that's a good sign, two independent tests coming to the same conclusion, the battery is just going bad.  Although maybe it's just coincidence ?  The Craftsman 82411 VOM puts an 18 mA load on the 9V battery or about 500 ohms.  The voltage level at the top of the BAD range was measured at 6.75 volts so the droop down from 7.5 volts is from the load current across the internal resistance of the battery. There is a W1FB article on a homebrew battery tester / VOM in the December 1992 issue of Monitoring Times: for the 9V: 820 ohms versus 500 ohms (11 mA versus 18 ...

Continued from yesterday: https://wb9kzy.blogspot.com/2026/06/morsemaster-ii-shaped-code.html   I did try the MorseMaster II sidetone on the solderless breadboard.  It actually works pretty well.  Here is an short pulse from the LM380 output with the RC filtering: It seems to me that I tried this circuit before but found it thumpy.  This time the thumping is minimal.  The two high pass RC pairs may account for this - I may have not used the spec'd parts before.  The only problem, noticed with headphones, is backwave.  There is a low level audio signal coming from the 555 chip which is running all the time - think of it as an on frequency QRP audio station which is key down all the time ! The backwave can be reduced by adding a series resistor to the headphones, I tried 180 ohms but more experimentation might help. Update, 2026-6-18:  I tried a 1000 ohm resistor in place of the 180 ohm, really seems to knock down the backwave, of course the  v...

How many zillions of 555 based code practice oscillators are there beeping away ?  Probably quite a few - I remembered that my MorseMaster II project has one, previously mentioned here: https://wb9kzy.blogspot.com/2026/02/bad-cap.html     But the original MorseMaster II design by Mike, KJ4LN cleverly upgraded the 555, adding shaping to the waveform and RC filtering: So I thought about adding those circuits to my MorseMaster.  One interesting note: the 555 in the Morsemaster II runs continuously so really the circuits add keying, shaping and filtering.  The steady 555 current doesn't matter that much considering the power used by the microcontroller is fairly high. First, using a solderless breadboard, here are the full pulse and the zoom in on ramp up / down waveforms all at the the collector of Q4: . 4 ms rise time 8 ms fall time Next, here is the shaped square wave, with rise and fall zooms: That's about as far as I gotten so far, I'll add the filter and LM380...

I get an email from Nuts and Volts magazine weekly with some links to free articles (see the newsletter signup link at the bottom of the page): https://www.nutsvolts.com/ This article caught my eye recently: https://www.nutsvolts.com/magazine/article/some-simple-transistor-and-ic-circuits Here is the web site of the author, KE3FL:   https://www.cs.yrex.com/ke3fl/ The circuit that interested me was ramping the brightness of an LED up and down slowly to blink it.   I finally read the article, the circuit is a phase shift oscillator but at less than 1 Hz so the caps are big (electrolytics).  The author's video looks good although it's in subdued light.  I had a little trouble getting the circuit to play (didn't have a white LED at hand) so I tried simulating it with LTSpice: the green trace is out, the blue trace is sine this is the collector voltage Since it does seem to simulate I tried fiddling with it - got it to sustain oscillation by increasing the series res...

Yes, I do still sell the AT-121 piezo sounder on the switch and parts page (this blog is called: A Crummy Commercial for a reason :) http://wb9kzy.com/switch.htm The AT-121 is 35 cents but they do look a little grungy and have short leads - I also still sell the larger CPE-6080 piezo at $2.50 each. However one thing the AT-121 has that the CPE-6080 doesn't have is a third, blue wire - this is a feedback area of the piezo.  It's used with this type of simple circuit shown on the datasheet: I realized that I never tried this circuit - when I've used the AT-121 in my own projects I always drove it via the red and black wires by a square wave from a PIC.  The blue wire was just clipped off.  But what are the advantages of the datasheet circuit ?  The main one that comes to mind is that it is simple but also since it operates at resonance, loud.  That volume is bordering on obnoxious at 9 volts but must be ear splitting at 28 volts. So anyway I did try the circuit on...

I finally found the CQ Magazine article by W1FB from October 1997 on an antenna switch construction project.  I've mentioned it several times, for example: https://wb9kzy.blogspot.com/2022/10/dougs-desk-in-cq-magazine.html Here are the schematics: I remembered the article as using automotive relays (aka Bosch) which is correct BUT I also remembered it as employing a power saving circuit for the relays - that isn't true. So I don't know if I am thinking of a different article/author or ?? Here is a short relay power saver video: source:  https://www.youtube.com/watch?v=CqLfx7yIhIE It shows the concept of bridging a series resistor with an electrolytic cap - this allows the relay to pull in but the relay current decreases as the cap is charged. I don't know what to say about my memory though :( Best Regards, Chuck, WB9KZY http://wb9kzy.com/ham.htm