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    Audio amp modification

    I want to drive a pair of speakers which have internal crossovers with an amp which has separate woofer/ mid and tweeter amps, as shown in the circuit. The existing speakers are fitted high up in a building, and have the standard pair of wires going to them. I can't get to them to separate...
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    Ultrasonic cleaner

    I have an ultrasonic cleaner which has a dead control/supply board. Instead of repairing the board I would like to just power up the transducers (they are the flat circular type) and use a timer to switch it. I was thinking of using an oscillator operating at about 40kHz, and run that through...
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    SOP14 to DIL14

    Does anyone make a small pcb on which a SOP14 package can be soldered and have external terminations which can be either be plugged into a normal Veroboard rail or DIL IC socket? I can only get a SOP14 package and it is replacing a DIL14 pin IC.
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    Low voltage drop diode

    Is there a diode which has a lower voltage drop than the standard 0.5v for a silicon unit, but I need something which can handle up to 10 amps. The germanium type were less, but I don't think there were large power ones made, only small signal type.
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    18650 cell matching

    I have just got a large batch of used 18650's which I have sorted and capacity checked. I want to make a battery pack, 6P / 3S, ( and using a suitable charger,) and would like to know about matching capacities. Is it more important that the series groups , the parallel groups or the whole lot...
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    Dim fluorescent display

    My old (about 35 years) microwave has a multi-digit green fluorescent display, and has been in constant daily use since new. I have just noticed after so many years that the display is hardly readable- I have been using it on the same setting, so never really took much notice of the display. Do...
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    VFD voltage

    I have a VFD driving a 3 phase motor (220V). The setup works fine, but I decided I need to run a small 24volt transformer to operate the switchgear. I thought I may be able to connect the primary of the transformer across 1 phase of the VFD output, but when measuring the AC voltage across 1...
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    Lead-acid charger

    I have a lead acid (car type) battery charger given to me to repair. I found that it had been subjected to a high load on the output, which cooked the ammeter and permanently open circuited the bi-metal overload protector. I measured the output before this mess, and on the 12volt setting, I am...
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    18650 charging

    I have found a cordless vacuum cleaner which had no plugpack/power supply. It has a battery pack of 18650's, 29.5v worth, and the charging "smarts" are all in the battery pack, so there is only a D.C. input jack on the side. I have set up another bunch of 18650's in series, with an ammeter and...
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    Micro USB cable

    I am looking for a micro USB plug lead which has a way to connect to the wires, like a "breakout box". I could just chop the end off an existing usb lead, but the tiny conductors are a little fiddly to terminate.
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    MOV protection

    When an MOV is exposed to an over-voltage (fault condition), do they normally fail to an open or short circuit?
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