A Crummy Commercial

I took a second look at measuring the leakage current of the Renogy solar panel - that first reading of ZERO current kinda bugged me. https://wb9kzy.blogspot.com/2026/05/the-renogy-solar-panel-dischargeleakage.html   I used the newer Triplett DVM just in case there was some kind of problem with the Metex used before.   At 12.84 volts I again measured zero current in any of the three ranges. So I was thinking about that and this is my surmise: there are lower voltage Schottky diodes like the 1n5818, 1 A diode I used on the other solar panel.  The low voltage diodes have somewhat high leakage currents.  Then there are higher voltage Schottky diodes for use in switching supplies and the like.  They have higher forward voltages but smaller leakage currents.  Here is part of a Nexperia Schottky diode data sheet: I will have to pay the tariff tax and get some of these How does this fit in with the Renogy solar panel ?  The Renogy has 72 solar cells which I a...

The current maple sap boiling setup/results was mentioned previously: https://wb9kzy.blogspot.com/2026/03/maple-syrup-update.html I still would like to improve the process if possible at reasonable expense.   The internet (and the real world, too) is an easier place when you get to know the specialized vocabulary of an area of interest.  In the case of measuring the mass of distilled water the term I needed is: check weigher.  A check weigher is a scale with a light or alarm when the item being weighed (massed) is either too heavy, too light or just right. This is what I need for monitoring the distilled water output of the still while boiling the maple sap down to maple syrup.  Here are some examples from McMaster-Carr and Ebay: love the stop light type design $847.06 (plus shipping and tax):  https://www.mcmaster.com/products/check-weighers/go-no-go-digital-display-bench-top-scales~~/ $188.85 (but Fedex):  https://www.ebay.com/itm/305239215849 $153.7...

Continuing with the maple sap / syrup saga: https://wb9kzy.blogspot.com/2026/03/dialing-it-in-part-ii.html I did start using the Ozeri scale to measure the input mass of the sap AND the output mass of the syrup.  Also I tried to account for some condensation drops inside the top of the still.  So the amount of loss to evaporation seems to be roughly 40 grams of a 4000 gram sap input or 1 percent.  The longer the boil the more the evaporation loss. In addition, instead of measuring the output volume of distilled water I'm now measuring the output mass near the end of the boil rather than when the boil was finished.  This lets me make a better decision on when to stop the boil.  I just happened to have this shelf on my bench to support a power supply.  It is the perfect height to boost the still above the Rubbermaid pitcher. Because the scale turns itself off after 2 or 5 minutes I have to wait until near the end of the boil.  Then boost up the pitcher, ...

Feeling adventurous I decided to take a gander at the insides of the Triplett MM350.  First task was to figure out how to get the red rubber boot off.  This was fairly easy after I realized there were four slots in the plastic case and four tabs on the rubber boot:   Note that this makes the serial number easier to see: Also, the only thing I don't like about this meter is the battery holder.  The cells spring out of the holder - it's hard to get the battery cover on while trying to keep the cells in the holder. After taking out the 6 screws the back comes off easily: There are two replaceable fuses, so now I know how to get at them if needed. Here is a slightly closer view of the circuit board: Unfortunately the main chip is "blobbed" - I was hoping it might be packaged so that I could read the part number and vendor.  I suppose the number of pins and the type of package might reveal something ?  But if I really want to know I'll have to ask Triplett. Why ...

I received the Triplett MM350 from DigiKey on Wednesday: It's a little smaller than the Metex ME-11 - I was expecting 3 x AA cells but they are AAA cells.  The ones supplied are carbon zinc so I'll have to keep an eye on them - don't want a leak.  The battery door is a little easier to open than the Metex which has an awkward slide and captive machine screw.  I did try the temp sensor which works fine but it was hard to insert the banana plugs, a tight fit. But the thing I really wanted to try was the frequency counter and duty cycle percentage as they might be used to measure Morse code speed and element weight.  So I hooked it up to a PK-4 keyer and nothing !  Then I realized that the counter needs an AC waveform not a positive pulse train.  So I connected a 100 uF cap in series with the output and voila, I've got frequency: The red LED display is the Morse Speedometer from the project page: http://wb9kzy.com/projects.htm  The MM350 reads 13.71 Hz wh...

Recently I was working on a project and realized that it would have been nice to have a 2nd multimeter to measure current while the Radio Shack meter was measuring voltage.  In addition, the Radio Shack is getting creaky, previously mentioned here: https://wb9kzy.blogspot.com/2025/03/loss-of-trust.html  And finally, a customer made a kit inquiry asking about Morse weight measurement aka duty cycle.  Well it turns out that a lot of recent meters can measure both frequency AND duty cycle, nice ! I looked at the inexpensive Fluke meters which aren't cheap at over $100.  And the HP  Keysight handhelds are like twice that much.  But one name caught my eye: Triplett. https://wb9kzy.blogspot.com/2022/11/tempted-by-triplett.html   Triplett has a range of offerings but this one is about the cheapest that includes frequency and duty cycle: notice the Hz/Duty button and the Hz% rotary switch position https://www.triplett.com/products/mm350-4000-count-true-rm...

I did try the microammeter from the previous blog: https://wb9kzy.blogspot.com/2025/04/nanoammeter.html and it does work, giving 2 more digits of precision to current readings - more digits not necessarily more accuracy :) The quiescent current used by my two fave LDO regulators, the S812C50 which I usually measure as 1 uA with the Metex ME-11 in the 4 mA position measures as 0.58 uA with the following circuit: So the Metex is rounding up to 1 uA from .58 uA - seems reasonable.  With the LM2936 I usually measure 7 uA with the Metex, now it measures 7.31 uA using this new technique.  So in that case the Metex is rounding down the reading. What is the error from putting the two resistances in parallel ?  Very tiny, I work the equivalent resistance out as 9990 ohms which is 99.9 % of 10,000. (10k x 10 meg) / (10k + 10 meg) = 9990 ohms A 10 k ohm, 1 percent resistor is pretty cheap compared to a 5 1/2 digit DVM ! Best Regards, Chuck, WB9KZY http://wb9kzy.com/ham.htm

I've mentioned microammeter add-ons before: https://wb9kzy.blogspot.com/2022/04/microammeter-add-on-circuit-for-dvm.html  and https://wb9kzy.blogspot.com/2022/04/microammeter-dvm-add-on-part-2.html  Recently in addition to searching the web for technical topics I've also started searching Youtube.  Seems like there are a number of folks on Youtube doing technical videos - maybe to monetize their info ?  Doesn't really matter, I tried searching Youtube for nanoammeter (actually started with picoammeter but that seemed way too fussy and microammeter results in a lot of old videos about D'Arsonval meters).  This is in reference to this recent post: https://wb9kzy.blogspot.com/2025/04/current-measurements-on-ldo-regulators.html Anyway, I thought this design was interesting, for one thing: no bi-polar supply (or op-amp) required: source: https://www.youtube.com/watch?v=kKWA4L_ZaI0 A clever video !  I've got to try it. Best Regards, Chuck, WB9KZY http://wb9kzy.c...

After futzing with NanoVNA Saver and various computers, also spending time looking for a USB soundcard (for a different project) I finally just hooked the NanoVNA to my 30 meter inverted V.  This SWR plot explains a lot: 10.7 MHz, that's the IF frequency of FM receivers !  To me this says that I cut the antenna too short, who does that ?  It is still kind of cold and windy for antenna work (and tomorrow is supposed to be a deluge) so I will delay messing with the antenna for now.  Also remembered that the pulley at the top of the pole isn't working so the antenna will have to be taken down to ground level.   No wonder the K2 tuner couldn't find a 1:1 match !   Best Regards, Chuck, WB9KZY http://wb9kzy.com/ham.htm

I made a quick try at sending some CQs on 30 and 10 meters to generate reports on the Reverse Beacon Network.  However when I plugged in my 8 pin keyer in the phenolic case and hit the memory button the K2 went key down.  I also tried sending with a straight key and got similar results.  Strangely I was able to use the internal K2 keyer with an external paddle and got one lone report on 30: One thing that can be done for RF feedback problems is to use a keyer in a metal case.  I would have sworn that I had one at hand but no luck.  Then just as I was about to build yet another keyer but this time in a metal case I made one last search and found this: It's an Island Keyer II: http://wb9kzy.com/ik2.htm It was built into a Swiss Colony candy tin: One unusual feature is this: It's a temperature sensor sticking out of the side - there is a small amplifier that scales the LM34 sensor output to the Island Keyer II analog input, this is mentioned in passing on page 5 of...

Oh No !  What's this on the right ?: Two empty holes have appeared since yesterday: https://wb9kzy.blogspot.com/2025/01/hp-fanciness-aka-hp-16058a.html Decided to liberate two of the pin jacks from the HP 16058a.  Here they are: And in action: Later I put some heat shrink over the positive terminal to prevent accidental contact.   BTW, I did price pin jacks (which I may still buy in the future)  they are over $1 each so my purchase of the HP 16058a in 1991 has been more than justified ! Best Regards, Chuck, WB9KZY http://wb9kzy.com/ham.htm

In the process of working on the 555 metronome I was using my B&K 2190d digital scope. B&K 2190d   It has a lot of nice features including measuring the period of a waveform.  But it only does this to a precision of 10 milliseconds for a long period waveform (over a second in this case). I got out a frequency counter that I had purchased on ebay, but it doesn't measure waveform period.  I do have an HP 5328 counter but unfortunately it needs fixing. Then I recalled a Morse Speedometer project I had (see http://wb9kzy.com/projects.htm ).  I got it out thinking that it would "display" the period in Morse code.  But it didn't work.  So I dug into the code and got it to read half the period.  The resolution is 100 us. The 555 timer outputs a 15 ms wide blip up to 9 volts and then goes low for the rest of the period.   For 40 beats per minute the period is 60 seconds/40 beats or 1.5 seconds/beat so 15 ms high, then 1485 ms low for 1500 ms tota...