HarryA

I would work on the voltage first. Although the specs, say 3.0V ∼ 5.0V for the RTS0072 ,there must be problem somewhere. The condenser mic. should not be drawing any current, try disconnecting it then recheck the voltage. Pop out the RTS0072 also. Specs. for the chip are here (see the second circuit which is like the one you are using): https://www.experimentalistsanonymous.com/diy/Datasheets/RTS0072.pdf

The 1.69 volts at pins 11 & 12 suggest the Zener diode is in the wrong orientation. The 1.69 volts is the forward voltage not the reverse voltage of 4.7 volts you are looking for. If not try popping out the RTS0072 and recheck the voltage, perhaps it is shorted.

I looked at your photo in photoshop where I could enlarge it, looks okay from what I can see of it. Check the voltage at the speaker and pin 6 of the LM386 for the 6 volts. Also check the voltages at the mic. and pins 11 & 12 at the RTS0072 for the 4.7 volts off the Zener diode. It is best to check voltages at the IC pins if you can. Also you could in similar manner check the ground connections with the meter. Could be a bad RS0072 ?

Without a schematic of your circuit and a closeup photo of your circuit it is not possible to help you.

There are two types of USB power suppliers; the USB power supply and the USB power supply charger. It appears you are using the charger. Consider using a USB hub connected to the charger then connect your led/motion detector plus a simple LED device. The LED device would have a constant drain to keep the charger active? see for example(18ma). https://www.amazon.com/dp/B07RR3FQWF/ref=sspa_dk_detail_0?pd_rd_i=B07RR3FQWF&pd_rd_w=945qJ&content-id=amzn1.sym.0d1092dc-81bb-493f-8769-d5c802257e94&pf

Comparing the two data sheets they appear to be nearly identical. the MMBT3904's higher current rating may make it last longer.

Here is a circuit that may work for you. I have a 10k thermistor and a MJE3055. I could try it on a breadboard if you like; converting it to 12v.

That is most likely an internal factory number. Remember they do not want you to repair them but to buy new ones. There are a number of videos on youtube in regard to chargers. Search on " Black&Decker 18V Li-ion charger " for example: https://www.youtube.com/watch?v=c-pTziUV1as

I believe this is what you need: push botton switch.asc push botton sw.xcf

Is the action like this? I got to many cd's Are you comfortable using a micro-controller like an Arduino UNO? time: action switch 1 switch 2 0: hv pulses charge C1 at ca at cd S2's 1: C1 is charged to 24v at cd at cc 2: hv pulses applied to V at cb at cc 3: C1 drops to 17v at cd at cd S2's 4: hv pulses charge C1 at ca at cd S2's cycle repeats

What types of short period are you interested in? What divert times are you interested in? An inductor in series with the source and load would retard the current going out and when the magnetic field collapses there would be a back emf towards the source. A length of coaxial cable would form a delay line. If not terminated to match the cable at the load a pulse would be returned towards the source. see: analog delay line

I used an optocoupler between an Arduino Uno and a mosfet at 350 volts for an capacitor discharge ignition circuit.

VARIAC

Multi-turn pots makes it slow to make adjustments. As Vellerman did not use them perhaps you could replace the pots with good ones like Allen-Bradley pots. Beware of the various tapers that pots have. Check Ebay for good prices on Allen-Bradley pots from US suppliers.

Are you using the information from Jaycar site? There is lot of information on their web site in Specifications and Articles. https://www.jaycar.com.au/atmega328p-mcu-ic-with-arduino-uno-bootloader-and-16mhz-crystal/p/ZZ8727 The manual is here: https://www.jaycar.com.au/medias/sys_master/images/images/9794372567070/ZZ8727-manualMain.pdf

Forums like this one would be more useful for your questions. They have folks there that have a lot of combined experience. https://www.solarpaneltalk.com/

What code book? And why do you care? Unplug the refrigerator and plug it into one of these. https://www.ebay.com/itm/293616232230?_trkparms=amclksrc%3DITM%26aid%3D1110018%26algo%3DHOMESPLICE.COMPLISTINGS%d%3APL_CLK|clp%3A2047675

As this was in response to a previous post that was removed I will replace with a joke: Wife texts husband on a cold winter morning: "Windows frozen, won't open "Husband texts back: "Gently pour some hot water over it and then gently tap edges with hammer." Wife texts back 10 minutes later: "Computer really messed up now."

I would think these 5 volt and 5 or 8 ampere power supplies would be useful for micro-controllers, etc. https://www.sciplus.com/8a-5vdc-power-supply-65520-p

If you are handy with a soldering iron you can get a push button switch with potentiometer on ebay. for example: https://www.ebay.com/itm/113927101102?hash=item1a86959aae:g:TyAAAOSw6ShdqKXJ&amdata=enc%3AAQAHAAAAsCTccvK8zt8P7ay7xO2JNnQVqK54hb11np% You would need to match the potentiometer on the switch with the one on the timer board. You could replace the potentiometer and switch on a timer board like this perhaps: https://www.amazon.com/Module-Adjustable-Timing-Switch-1-10sec/dp/B07SL5HBZ9/ref=sr_1_58?crid=3806JFZG2WCBO&keywords=time+delay+board&qid=1670774252&sprefix=time+delay+board%2Caps%2C129&sr=8-58 Look for one with the delay you need.

"Search for the power board for a Tektronix oscilloscope mod. TDS460. The P/N is PS1690 rev.A" In the future you may use https://translate.google.com/ There are a number of boards on ebay.com for the TDS460. You will have to scroll down to find them. See: https://www.ebay.com/sch/i.html?campid=5338192028&kw=TDS460&mkcid=1&mkrid=711-53200-19255-0&toolid=20004

Is Rolling Meadows, IL 60008 near you? see: https://www.solder.net/training-courses/bga-rework-training/ See for low key diy rework: https://www.instructables.com/BGA-rework/

You need to supply a link/url to the DXP software you are using. There are numerous software packages called DXP.

see: https://en.wikipedia.org/wiki/Button_cell for chemical composition of the CR2032 cell. The C tells you it is Lithium and Manganse Dioxide.

You have been well answered on the numerous forums you have posted this question on. I do not see anyway to post links now - Admin got sick of having to delete them?