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  1. KrisBlueNZ

    Adjustable brightness torch??

    They don't have BUZ11 but that one is suitable for that circuit.
  2. KrisBlueNZ

    Yamaha integrated receiver SR-300 subwoofer not working

    It has to be soldered in, and it's an SMT (surface mount technology) device with pretty closely spaced pins. Google SMT desoldering and SMT soldering to get some guidelines on how to remove the old one, and how to reinstall the new one. I suggest you practice on some broken piece of modern...
  3. KrisBlueNZ

    Adjustable brightness torch??

    That lot sounds OK. Maplin do have one suitable MOSFET: http://www.maplin.co.uk/p/irf540a-mos-fet-transistor-to220-case-n10ah The photograph on the web site is wrong. Just ignore that!
  4. KrisBlueNZ

    Increasing Frequency With Time

    Hi Jimbob and welcome to Electronics Point :-) It could be helpful if you posted a schematic of what you have so far - i.e. the down-counter.
  5. KrisBlueNZ

    Designing a Time Delayed Relay

    :) I don't think there's any good reason not to put a copper fill under it, but I don't think you'd gain anything by putting groundplane there, so I advise you leave that area blank - unless you want to put SMT parts there, as I suggested in an earlier post. (In which case you need to keep them...
  6. KrisBlueNZ

    Designing a Time Delayed Relay

    There's no point putting a slot between the two pairs of pins on the same side, because there's almost no voltage between them - they're joined together by a bit of metal inside the device, and the only voltage that appears between them is a few millivolts caused by current flowing through the...
  7. KrisBlueNZ

    How to Step up Voltage? DC to DC converter or Op Amp

    OK, that circuit isn't suitable for driving an Arduino input. Here's a circuit that is. I've used a dual op-amp, the LM358, even though only one half is used. This is your most easily available option. You can't use a 741 here as BobK said because it's not a single-supply op-amp. The op-amp...
  8. KrisBlueNZ

    Dead Automatic Battery Charger for Autos. Please help me troubleshoot.

    I disagree in this case, because the original relay, in this case, is a "SANYOU" brand! In my experience, Chinese look-alike names are a sign of low quality ("Transonic" TV sets, anyone? How about "Technical Pro" audio gear?) and in any case, the charger is apparently rated for a maximum...
  9. KrisBlueNZ

    Adding aux input to Sony PMC-202 stereo system

    Make sure you didn't forget to plug anything back in. Also make sure the FFC is around the right way.
  10. KrisBlueNZ

    How many people can fix electronic devices?

    In my experience, that IS uncommon. It does happen occasionally, but not often. It depends on what factors you ignore. Some good reasons for repairing equipment that you are ignoring are: reducing environmental impact (e-waste); learning how things work; practice with soldering, reading...
  11. KrisBlueNZ

    How to Step up Voltage? DC to DC converter or Op Amp

    No, don't do that. A voltage doubler or tripler is not the right kind of circuit at all! You just need to increase the gain of the op-amp stage. If you just want a DC voltage that increases when more light falls on the LDR, you don't need much: VR1 should be a multi-turn preset...
  12. KrisBlueNZ

    4-20mA using XTR111

    I'm not sure what you're asking. But I have another suggestion that's a bit easier. Leave the two 120k resistors as they are. Replace the 4k resistor with a 5k multi-turn trimpot and use it to adjust the gain. Then adjust the offset by adjusting the 4V reference voltage, using the trimpot that's...
  13. KrisBlueNZ

    lm317 sub?

    I'm not sure what you're missing, but here's an explanation of the shunt-regulator-based constant current sink. Assuming the hFE of the transistor is high, the base current is negligible, so IE and IC (which is the output current IOUT) are almost exactly the same. So the output current...
  14. KrisBlueNZ

    Dead Automatic Battery Charger for Autos. Please help me troubleshoot.

    Can't say at the moment. It might be worth replacing it with a better quality one anyway. OK. No I hadn't seen it. Did you measure that diode in circuit or out of circuit? It's connected straight across the relay coil, so it won't measure properly in circuit. You'll have to lift one end. Then...
  15. KrisBlueNZ

    adaptor help needed

    Also, have a close look to see if there are any little metal bumps sticking out in the crevices that might be used to hide ultra-compact monitoring equipment. You can't be too careful these days. The NSA is always extending its reach.
  16. KrisBlueNZ

    Total Resistance of circuit, when there is current source

    What do you mean "the total resistance"? There are several ways that question could be interpreted.
  17. KrisBlueNZ

    Chip45 Boot2 GUI, AVR Studio 4, MPLAB IDE, WinPic800, Tinyboot loader?

    No. I didn't mention C++ at all. The boot loader may be written in C, but most likely written in assembler because it should be as small as possible. The main firmware could be written in any language really. C and C++ are often used. Please, READ my previous posts. The boot loader does NOT get...
  18. KrisBlueNZ

    28 inch Monitor won't power on anymore

    OK, "KY" is just the lubricant they use when they slide the plastic bit on. Just kidding. KY is the designation for a series of low-ESR electrolytics made by United Chemi-Con (UCC) in Japan. You can get exact replacements from Digi-Key. Use this filter...
  19. KrisBlueNZ

    Dead Automatic Battery Charger for Autos. Please help me troubleshoot.

    OK, the transistor is connected the way I thought it was connected. It seems like the transistor is faulty or damaged, and it isn't activating the relay. It looks like Radio Shack have the transistor: http://www.radioshack.com/2n4401-npn-switching-transistor/2762058.html but it's not an...
  20. KrisBlueNZ

    Solenoid controller

    Actuates a "device"? Why so vague? Is your project a secret or something?
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