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  1. KrisBlueNZ

    Help with Jumbotron

    You mentioned a 9V power source. If you were hoping to use a 9V "PP3" battery (https://en.wikipedia.org/wiki/Nine-volt_battery) to power 25 LEDs, be aware that you'll probably only get a few minutes of operation before the battery goes flat. Each LED component contains three actual LED...
  2. KrisBlueNZ

    AA battery USB charger - phone is drawing too much current

    Even if you can convince the phone to charge at a lower current, if you use two alkaline AA cells, you would need to replace them twice during a single recharge!
  3. KrisBlueNZ

    How to break a faulty wireless keyboard and mouse.

    I don't recommend that you try to break it. Find out what your consumer rights are. What country are you in? Has the retailer admitted that the battery life is only three days and that the keyboard misses keystrokes? Here in New Zealand we have the Fair Trading Act which says that products...
  4. KrisBlueNZ

    Learning to use programmable integrated circuits

    I agree. C was designed to be efficient and powerful on 16-bit machines, and adapts well to 8-bit and 32-bit architectures too. It gives you many of the usual advantages of high-level languages, while still translating fairly directly to assembly language (the native language of the CPU core)...
  5. KrisBlueNZ

    Repairing power supply for fun

    I agree Steve, I don't see any power factor correction stage there. smashrc, I suggest you replace the bridge rectifier on suspicion, and replace the electrolytic, before you test again.
  6. KrisBlueNZ

    Apple Magsafe

    I'm interested in that comment. Is that because the adapter hiccups due to output overvoltage with no load, so the average output voltage you measure is lower than the specified voltage?
  7. KrisBlueNZ

    Repairing power supply for fun

    I'd suspect the bridge rectifier at the input. A very leaky diode in the bridge would cause those symptoms. It could also be something downstream, as Steve suggested - a MOSFET or a high-speed diode. But I suggest you replace the bridge first; they're not expensive. Edit: You could also check...
  8. KrisBlueNZ

    Learning to use programmable integrated circuits

    C++ is C with "object-oriented" features. This adds a lot of baggage that I don't think is appropriate for resource-constrained microcontrollers. I have heard of people using C++ on MCUs but I would not consider it myself. C++ is fairly widely used in the computer world though. That PIC...
  9. KrisBlueNZ

    Transistor Mosfet pairs to drive LED cube layers

    Cool! Great work Russell :-) BTW they sent you five boards because PCB manufacturers usually run extra in case of failures of various types, and with this run, they discovered there were five good boards from the run. Do you have a link to the video? Edit: Hey, take it easy with the...
  10. KrisBlueNZ

    Woo-woo projects.

    Congratulations GonzoEngineer on getting a gold star. Of course, everyone else got a gold star too. So there's no need to make your posts accurate or thought-provoking. I think it's a combination of factors. With the free exchange of information and automatic anonymity provided by the...
  11. KrisBlueNZ

    What value of resistors do I need and a sanity check

    Hi Zaid, My design is based on the design in post #45 on this thread. I think it is better than the LM334Z-based design, but it is very important (for safety) that the red LED cannot be broken or become disconnected from the circuit. You can use the circuit in post #45 with the following...
  12. KrisBlueNZ

    Help with replacing component on circuit board

    Excellent answer duke37!
  13. KrisBlueNZ

    Hi new here, CRT TV question..

    To discharge the final anode voltage, I use a wire with a large alligator clip on one end (clipped to the braiding and springs that make contact with the aquadag, the graphite coating on most of the rear CRT surface), and a piece of metal at the other end that you can slip under the ultor cap...
  14. KrisBlueNZ

    simple amplifier for LME49710

    Ah, some information about what you want to do! That's a help. but it's not enough. How compact is compact? What is your power source? You mentioned 3V, is that your power source? Are you planning on powering it from a coin cell? Generally, small eight ohm speakers have very poor sound...
  15. KrisBlueNZ

    What is this part an where can I get it?

    http://www.digikey.com/product-detail/en/TAP475K016SCS/478-1904-ND/564007
  16. KrisBlueNZ

    overheating of the variable resistors

    Another approach would be to use a single power supply in constant current mode, connect all the electromagnets in series, and put a low resistance in parallel with each electromagnet, as necessary, to pass some of the current, leaving less for the electromagnet. You would need fairly low...
  17. KrisBlueNZ

    simple amplifier for LME49710

    https://www.sparkfun.com/products/9612
  18. KrisBlueNZ

    Learning to use programmable integrated circuits

    The method you've shown, using _delay_ms(), is not suitable for your application. If you want to control several LEDs, with different timings for each, you would need several of those execution paths, running in parallel. An MCU with a single core (and all small MCUs are single-core) can only...
  19. KrisBlueNZ

    Learning to use programmable integrated circuits

    You're absolutely right. Small digital devices such as microcontrollers cannot supply 200 mA; you will need a buffer of some kind. MOSFETs are the logical choice (pun intended). Yes. Even a small PIC will be able to handle all your LED blinking requirements, though you will need to think...
  20. KrisBlueNZ

    Help with siren circuit

    You could start by posting a schematic of your ideas so far. You would like to make "this" a sinewave? The audio signal, or the modulation signal? You can use a 40106 as a modulated oscillator, but the thresholds are not well-controlled, compared to a 555 where the thresholds are pretty...
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