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  1. S

    Two phone batteries in parallel?

    I bought a relatively unpopular phone and therefore there are very few accessories available for it. I'd like to have a battery that can last the entire day on a single charge and so I was wondering whether I can wire in a second battery in parallel to the first. Would they both have to be of...
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    Request help interpretting LED max Vf spec in spec sheet

    This image is a page from a spec sheet for a Philips Luxeon LED. One part of the sheet suggests that the maximum voltage tolerated is 4.95 V. However the LED's maximum tolerated current is 1500 mA and this is reached at 3.85 V. Does this mean that the current remains at 1500 mA between 3.85 V...
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    Underpowering a RGB LED controller to achieve lower voltage output?

    I have a project for which I'd like to use one of these remote controls and receivers. They accept 12 v and use this to power RGB LEDs on strips. However I don't want to power LEDs on strips; I want to power some RGB LEDs in parallel which means I need to drop the voltage considerably (to...
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    Advice for buying a 12V 2A adapter?

    I need a 12V 2A adapter for a project and I want to make sure the adapter isn't going to burn my house down (the one I've got here is making fizzing and crackling noises). How can I determine that in advance? Are the particular manufacturer's I can buy from? The project is an LED lamp I've made...
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    Advice identifying type of wire and sheath inside hair-curling tongs

    This photograph shows the inside of a pair of electric hair-curling tongs. Can anyone advise me what is the purpose and material of the white sheath and what kind of wires is it covering? I'm intent on modifying the tongs by reducing the size of the stainless steel tube which covers the wires (9...
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    Trying to charge NiCads using a wall wart

    I made my own dynamo-powered bike light with a very simple circuit which charges some NiCad cells to keep the light on when I stop at traffic lights. Due to a disconnected wire, I used it without input which of course drained the cells. I tried to the charge them in this manner once before - by...
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    Lithium-ion batteries safe to play with?

    I have a couple of lithium-ion batteries from a broken smartphone. Can I use them for a project or are they too dangerous for a novice to play around with? I made a bike light that charges NiCad batteries using a dynamo with the batteries maintaining the light while stopped. I think I was...
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    Advice on purchasing a cheap bench power supply

    I live in the UK. I bought a really cheap power supply from a Chinese EBay seller and it broke pretty quickly. I'm now looking for another but I'm willing to spend a bit more; ideally less than £130, if that's possible. I've got quite a few hobbies of which basic electronics is one. I don't know...
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    Broken toaster

    My toaster broke and I'd like to see if I can fix it rather than replace it. I think it happened when I pulled the lever up manually to abort the toasting operation prematurely as is my custom. I saw a bright orange light under the toaster and at the point the lever would no longer stay in the...
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    Cheap variable power supply circuit stopped working

    I bought the below variable voltage power supply from eBay last year. It worked fine when it arrived. I left it alone for a while and it seems to have stopped working, The component with 330 printed on it appears to be overheating. Turning the potentiometers does not seem to affect the...
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    Problem with Heathkit IO-102 oscilloscope - vertical deflection doesn't change

    I have a Heathkit IO-102 oscilloscope - a modern marvel of electronic engineering! However my particular scope has a problem. It may have been caused by me applying a voltage that was too high for the settings (don't know whether they're susceptible to that) whilst I was figuring out how to use...
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    Dehumidifier not working - suspect fault in fan motor; easy fix?

    My grandmother's dehumidifier isn't working. It sounds to me as though the refrigeration system is still working normally, but the fan doesn't rotate. I took a photo of the motor. I don't have my multimeter available, though I suppose I could get one. The motor looks very strange. I don't know...
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