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  1. KrisBlueNZ

    Making a Touch Sensitive Suit

    How about using an accelerometer to detect when the wearer bumps into something. It wouldn't work with a slight brush against someone, but a proper bump would cause a sudden deceleration that probably wouldn't occur for any other reason. Just thinking out loud here.
  2. KrisBlueNZ

    Transistors switch on output pin or input pin

    Sorry Davewalker5, I've lost interest in helping you. I find you to be too opinionated and big-headed, and too resistant to learning, and you are not being up-front with us.
  3. KrisBlueNZ

    RC circuit

    OK, forget positive and negative charge for the moment. First, understand the capacitor's behaviour. Then you can get into its internal physics. The most basic definition of the behaviour of a capacitor is: It keeps the voltage across its terminals constant, unless there is a current flowing...
  4. KrisBlueNZ

    Transistors switch on output pin or input pin

    My guess would be that they only wanted the circuit to sink current and not source current. They could have used a diode but they may have needed more current than the 709 could provide, so they used emitter followers instead of a diode. Without a lot more context it's impossible to say. What...
  5. KrisBlueNZ

    Transistors switch on output pin or input pin

    I don't believe you. The VBE voltages are both dependent on the same quantities - transistor type and temperature. So as long as they are the same transistor type (from the same batch) and are kept at the same temperature, their VBE voltages may vary significantly, but they will always be...
  6. KrisBlueNZ

    Transistors switch on output pin or input pin

    As I said in post #11: The VBEs of the two transistors are supposed to track each other fairly closely. The transistors may be strapped together. Many transistor parameters vary with temperature. VBE is just one of them, but it's the one being compensated here. If both transistors are the...
  7. KrisBlueNZ

    Simple NPN transistor circuit help

    Yes. Your battery is connected round the wrong way. Neither the transistor nor the LEDs will conduct with that polarity supply. Also your LED symbols are missing the arrows. That means they won't emit any light :-)
  8. KrisBlueNZ

    3.5 mm jack internal connections

    Please answer these questions. 1. What is the part number of the jack socket you intend to use? 2. Do you have one of these in your possession? Or do you just have a data sheet? 3. Do you have a stereo jack plug to suit that socket? And do you have a multimeter?
  9. KrisBlueNZ

    automatic doorbell

    Right :-) It's a bit messy and large, with the requirement for 50% duty cycle, but I couldn't find any crystals that were a power of 2 multiple of 40 kHz :-( If I had, I could have done it all in a single CD4060 :-(
  10. KrisBlueNZ

    automatic doorbell

    Thanks Adam :-) Any particular part you liked? It's a lot bigger than the original circuit, but also a lot more likely to work properly!
  11. KrisBlueNZ

    LED Flasher help.

    Did you get it going properly?
  12. KrisBlueNZ

    3.5 mm jack internal connections

    Right. That was going to be my next suggestion... assuming he actually has a socket in his hands. If he doesn't, I guess a careful web search would be appropriate, for that specific part number first. (There seem to be two numbers associated with each part.) If he can find a clear enough photo...
  13. KrisBlueNZ

    ICSP for PIC microcontroller using USB

    You could duplicate the PICkit hardware on each board you make (including copying their firmware)... Or you could design your own programming interface using a micro with a USB interface (and write your own driver and/or application for the PC end)... otherwise I don't think so!
  14. KrisBlueNZ

    3.5 mm jack internal connections

    The stereo ones are on the second page.
  15. KrisBlueNZ

    3.5 mm jack internal connections

    Ah! The problem at last. Now you just need to tell me WHICH ONE of those jack sockets you're using, and we might get somewhere!
  16. KrisBlueNZ

    3.5 mm jack internal connections

    That's still very vague. The connections should be made with copper tracks. If you're asking which pin of the jack socket connects to which contact, that information should be in the data sheet fo the jack socket. If you can't find it, post a link to the data sheet and I'll have a look at it...
  17. KrisBlueNZ

    3.5 mm jack internal connections

    Stereo jacks (2.5 mm, 3.5 mm and 1/4") have three conductors: tip (at the end of the plug), ring, and sleeve (body). These connectors are therefore called tip-ring-sleeve or TRS connectors. When they are used for audio applications, the tip is the left channel audio, the ring is the right...
  18. KrisBlueNZ

    automatic doorbell

    OK, here's my suggestion. There are three parts to the design: two versions of the transmitter, and the receiver. I strongly recommend you use the crystal-controlled transmitter because it requires no setup and will not drift, but it's more complicated than the 555-based transmitter. If...
  19. KrisBlueNZ

    Digital Pots?

    Digital pots are best used as adjustable voltage dividers, rather than variable resistors, because their end-to-end resistance is not very well-controlled. They are not a general replacement for resistors because all terminals need to be kept within the device's supply rails (or slightly...
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