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  1. B

    Resistor to reduce voltage for a mini fan

    You have the current draw, and the voltage required on the motor and any resistor connected in series. With ohms law you can calculate the resistor size and just as important, the wattage of the resistor.
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    Signal meter salvage NHY6

    Probably quite a bit but with the info so far, don't think anyone can be of any specific help. Perhaps things like pics or model numbers may help.
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    RC car not going backwards

    Modern day controllers are not really made to be repaired. Process of elimation may be your best approach. Do you have any spares you can use?
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    Combined buck & boost converter?

    Alternator regulators do not "throw anything away" as you put it. They provide the necessary excitation to give a desired output with reference to requirements.
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    Touch on/off 12 LEDs switch with 50sec power off delay

    Ebay has timers that would suit and also Arduino have touch switches listed. If size does not meet your requirements then building your own on the basis of the above would be an alternative.
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    Nichrome wire help

    Goes without saying that you should have a fuse but not for control of the heat, rather to protect against faults. Now is where things start to get more complicated and, as larger currents are involved, more expensive. To begin with you need to measure the current that the circuit is drawing...
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    Keyless and contactless Reset switch

    Most hall effect switches are open collector and will handle voltages well over 12v dc . Don't forget a small filter cap on the supply pins of the hall effect ( around 0.1uf if I remember correctly). Also note that there are many types of hall effect and you will be looking for one similar to...
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    Nichrome wire help

    0.4mm @ 4' on 12v will give you around 13.68w per length which is approx double what you will get from the same length 0.3mm on the same voltage. You could run whatever number of strings( parallel runs) to get whatever final wattage you require. If the heat conduction into the filter is good...
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    Nichrome wire help

    Don't know what filter is being used but with a standard diesel filter of 100mm diameter, 500mm of this wire would not even go twice around the circumference so I don't think one would get much heat transfer from that setup. Even 3 lengths would be pushing it I think. Then one needs to get good...
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    Nichrome wire help

    Ah yes...my mistake. I was concentrating on nichrome and became a bit diverted onto what I used it for. Still, the same calculations will be necessary. Take the amount of wattage you require first up. Then decide on length and size of wire that will give that required wattage at your 12v...
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    Nichrome wire help

    When it comes to cutting foam, you are attacking the problem from the wrong end. I mentioned my approach above hoping you would see how to go about it. Above gives all requirements plus, with the dimmer on the transformer primary, an added advantage of good control over required heat for a wide...
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    Nichrome wire help

    According to one source, 0.4mm nichrome is around 8r per metre. So at 4r you will get 36w at 12v. If you want more heat, increase the voltage. Unit I use to cut foam is 48v transformer with a dimmer control on the primary. Source of wire here...specs in description...
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    Analog digital read

    Don't know of books but on youtube, Jeremy Blum has a series ( about 15) tutorials which go for around 10 minutes each and are reasonably good. Start at No. 1 of course. It usually helps to actually try each lesson and modify a little on your own just to see the effect. Learn a lot more that way...
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    Really basic circuit help needed (swtiches, LED, resistor and usb)

    I use a diode to detect current flow and then strap an npn transistor across the diode to switch any indicator led.
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    Dimmable led drivers?

    Note that there are many types of lamp dimmers and most are for a specific purpose and as such most will not work correctly with LED dimmable drivers.
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    Power source for smoke detector

    So what happens if one decides to false alarm? Any I have installed ( many) one has to access the problem unit to hush. I have seen commercial detectors with remote head units but never domestic type smoke detectors.
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    Can these two instruments test the transistors on my printer PSU?

    I answered that above where I said testing in and out of circuit etc. etc.
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    Amplifying a signal comming out from an aux port

    Aux out is meant to go to an amp or pre-amp. Maybe buy one on Ebay, plenty to choose from at much lower cost that even thinking about building.
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    Can these two instruments test the transistors on my printer PSU?

    Multimeter may be ok but one needs to know how to use it to begin with. Meter manual would help you there. Testing in and out of circuit can give quite differing results both for a shot device or a perfectly good one. Scope useful for live testing but once again one needs to know how to use...
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    Help putting timer on my welder

    The trigger switch more than likely operates currently on a low voltage so might be a good idea to find out what that is. Reason being it may be a factor in deciding what voltage timer unit to buy. One referred to above is 12v but there may also be others available e.g. 5v or 24v. Not a bad...
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