I built this “tungsten roadwork beacon” as Clive calls it, using the parts given in my schematic (photo below). I didn’t have a 6V, 90 mA lamp, so I simulated it by using three 20 ohm, 1/4 Watt resistors in series, which gives 60 ohms and 100 mA load with 6VDC. For an indicator I
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This may be helpful when choosing the amount of capacitance for a certain unregulated AC power supply – the kind that uses an old fashioned transformer. It calculates one variable given the others. https://www.chipbuilder.com/full-wave-power-supply-ripple-calculator.html
The gate driver circuit shown in the screenshot uses BC547s, which are limited to less than 200 mA current. Instead, if the two transistors were BC337 or PN2222A which can easily handle over 500 mA, they could charge and discharge the gate faster, and thus reduce the dissipation in the MOSFET.
This very comprehensive website has a transistor and FET Curve tracer. Also a simpler curve tracer for all components. Click on box to download the schematic, etc. https://www.changpuak.ch/electronics/Curve_Tracer_advanced.php#
I think this came from a crystal set made in Japan during the mid-20th century. It has a ball on the end of the ferrite rod like the crystal sets that were shaped like a rocket and this ball was at the rocket’s nose. The coil measures 38 to 380 microhenrys depending on the position
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James Chessman gave me permission to use his comment. “””I have encountered a phenomenon called “age-down” in ceramic capacitors tested on ICT (In-Circuit Test) machines. I was working for a circuit-board manufacturer, developing new test sets. I was seeing these caps consistently read high in new tests. And, pulling them out of the circuit they
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Chuck commented about the audio oscillator being a BFO, and it reminded me that I’ve got an old RCA BFO audio oscillator stuck away in the garage. It was a cheap way of getting an audio sine wave that covered the full audio band without any switching. Nowadays it’s all done in sine and other
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He uses my SJT circuit in his web page. https://devopedia.org/joule-thief-circuit
Here is a wealth of information about much of the electronics that is used by government entities especially the military. You can find out what the system is for data processing hardware. This used to be called JAN – Joint Army Navy. https://en.m.wikipedia.org/wiki/Joint_Electronics_Type_Designation_System
I’ve been discussing the restoration of a hundred y.o. radio, and I thought about the retro light bulbs that look like incandescents but use LED filaments. Someone should make some old tubes that are actually using LEDs that look like the filaments, but just for decorative purposes. The glass envelope would look like the tube;
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