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    VFD (Variable Frequency Driver) for 3-phase motors.

    Think you will find the circuit shown would be a much simplified version drawn up for the purpose of understanding basically how it works. There will be a lot more to it including the uC requirements and programming. I would not imagine a standard pwm generator programming would be sufficient to...
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    Blocking Oscillator

    Some of your comments show a distinct lack of knowledge on the subject. The oscillator unit at best will give around 200v to charge the cap. Some were aiming at a 400v mark to run engines up to 30,000rpm but as far as I remember 15,000rpm was where most topped out. The oscillator feeds the CDI...
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    Blocking Oscillator

    I don't see the humor in that. Perhaps you would like to include some of your working examples. I'd like to have 2 bob for every DIY that thinks building a CDI is easy peasy. Big difference between seeing a spark jump whatever distance in free air to actually working inside a purpose built...
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    Blocking Oscillator

    Used to make these CDI units for rc engines with just a basic hall effect as a trigger. Later this went to microcontroller for advance but finally went to commercially available gear. Mainly because winding the little step-up toroid transformer was a right PIA. Made a device which made this...
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    Frequency response ?

    LED is d.c. It will only show average as far as I am aware.
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    AOR AR2000 Radio Fault

    Looks to me like your original suspicion was correct. i.e. looks like a black marker pen, not leakage.
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    Sensor choice for pond water depth

    Ultrasonics units like this always have 2 elements. One is the transmitter and the other is the receiver.
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    AOR AR2000 Radio Fault

    Air Force days have come and gone........ Other may want to comment but have you thought about applying some heat?
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    AOR AR2000 Radio Fault

    We had a similar one here before the 2013 flood ......my son is Michael also and he used to listen in on all the air traffic before he was eventually accepted to the RAAF. ( way back now in '92.) That declining whine with the pop at the end in the video ( as I said before) sure sounds like a cap...
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    AOR AR2000 Radio Fault

    Yes but thought perhaps they were already flat. Wasn't mentioned first up.
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    AOR AR2000 Radio Fault

    Alkaline .....maybe or maybe not. Specs say the radio draws approx. 100mA but there are many "if's" that crop up there as to how long Alkaline will last. According to many sources, no where near as long as a NiCad charge of supplied cells. In fact it is quoted that the NiCad may last up to 4...
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    AOR AR2000 Radio Fault

    What batteries are you using and which ones are recommended in your owner manual?
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    2-channel passive mixer-independent volume control for each pickup

    I'm guessing it's the pickups then....o_O Once built an electronic stethoscope for finding location of engine noise. Plan called for magnetic earpiece as a pickup mic but all I had was crystal. ( wouldn't work). Ordered magnetic mic like was specified and still working 30 years later.
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    Microwaves to destroy termites in wood

    Ants invaded my kitchen and microwave one night so first thought was zap them. Placed a cup of water in the microwave for a load and gave it 1 minute. Water heated and ants still ran around merrily like nothing happened. ( go figure) Of course they did glow in the dark after...
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    How do digital sewing machines fail? Is there often a visuall clue on the circuit board?

    Well, you supplied next to zero info so you get what you came for, an answer as broad as your query.
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    How do digital sewing machines fail? Is there often a visuall clue on the circuit board?

    Could be anything from a broken wire to a so-called repairer induced problem and anywhere in between. Basically much like how long is a piece of string.
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    Vintage Mica Cap Value ?

    Might be a paper capacitor. https://antiqueradio.org/recap.htm
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    Lithium ion polymer battery: What is the 3rd (yellow) lead? what can I use for a replacement?

    It is conceivable that reusing the existing protection board with a new battery of similar capacity might be an acceptable alternative.
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    adheasive backed foil tape

    What foil?
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    switch mechanism

    Rc will be good for 500 metres at sea level at least, maybe more. Depends how high the waves are...:D
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