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  1. KrisBlueNZ

    I know nothing! But have questions

    Hi zesty and welcome to Electronics Point :-) I guess you've never heard of the famous Northern Dancing Maples of Moldova then? This sounds like an interesting project! Thanks for the photos. There's a lot of good detail there. I would like to see some specific parts of the unit though...
  2. KrisBlueNZ

    How do I build a Metal Detector?

    No. This is what you are trying to do at the moment: Connecting an inductor between two pins of the PIC Generating pulses on one pin Measuring the amount of time taken for the pulse to travel through the inductor using a timer monitoring the second pin. This is what you need to do: Make an...
  3. KrisBlueNZ

    Some help on bypass and filtering needed.

    Hi Andreas and welcome to the Electronics Point forums :-) I'd like to add some minor points to those good answers. I think one 0.1 µF ceramic or multi-layer ceramic capacitor per digital IC is enough; I do not use a 10 µF capacitor on every digital IC as well. Exceptions are high-current...
  4. KrisBlueNZ

    How do I build a Metal Detector?

    OK. First, an inductor doesn't have an "input" and an "output". You need to use it as part of an L-C "tank" circuit in an oscillator. The frequency of the oscillator is determined by the capacitance and the inductance. The inductance will change very slightly when the inductor is brought near to...
  5. KrisBlueNZ

    How do I build a Metal Detector?

    Have you heard about comments? You use them throughout your program to describe what the program is doing. They are almost as important as the code itself because they enable other people to follow your logic, and they will also remind you of how the program works when you come back to it in...
  6. KrisBlueNZ

    How do I build a Metal Detector?

    Can you post a schematic please.
  7. KrisBlueNZ

    Transistors heating up when sinking from motor

    I don't think that's the situation. Back in an earlier post he said: ... and I've been assuming that this 43.6 mA collector current was the actual measured current, not "calculated" as he says above, because I don't know how he would have calculated it. It's not the result of calculating...
  8. KrisBlueNZ

    Transistors heating up when sinking from motor

    Hmm, you're right kpatz. I thought the 3904/3906 were more like 600 mA. He said he has used them with LEDs and found they were OK. But I'm not convinced that they can deliver 200 mA. snake0, there's an easy way to test them: replace the motor with a resistor that will draw 200 mA. R = V / I =...
  9. KrisBlueNZ

    Circuit rectification help

    No, Steve is talking about the actual electrical characteristics of the circuit, not the logic - yet. Your gate inputs are being driven from switches from VCC, but logic gates need valid logic levels at their inputs at all times.
  10. KrisBlueNZ

    Transistors heating up when sinking from motor

    No problem. Remember to place negative feedback on the seller! Try to help others from having to go through the same trouble.
  11. KrisBlueNZ

    Transistors heating up when sinking from motor

    I think you might as well throw them all away. If they all have extremely low gain, paralleling them isn't going to help.
  12. KrisBlueNZ

    Transistors heating up when sinking from motor

    Oh, the emitter follower configuration? In that case, you were connecting the base directly to VCC (positive supply rail), right? So the motor current could have been flowing through the base-emitter path of the transistor, with no (or little) current flowing in the collector. To test for this...
  13. KrisBlueNZ

    Transistors heating up when sinking from motor

    If the motor "takes current from the emitter"? If you connect the negative side of the motor to the emitter, you have connected the motor straight across the battery and the transistor is not part of the circuit. That's why it would work.
  14. KrisBlueNZ

    Transistors heating up when sinking from motor

    Looks OK but I can't be sure. Need to be able to see the transistor and the connections to it in more detail.
  15. KrisBlueNZ

    Transistors heating up when sinking from motor

    That doesn't make sense. A base current of 11 mA will saturate the transistor and it should have no trouble passing 200 mA. Vce should be 0.3V or less, and you should see at least 4.7V across the motor. So you measured 43.6 mA current flowing into the collector? That sounds like the transistor...
  16. KrisBlueNZ

    detector circuit falling off too quickly

    LOL Chris :-) Yes, you can find it on instructables.com: http://www.instructables.com/id/simple-mobile-detector-circuit/?ALLSTEPS I found the same design on many web sites. The diagram and the accompanying text are copied verbatim, including a distinctive grammatical error. Just try this...
  17. KrisBlueNZ

    Transistors heating up when sinking from motor

    Only 0.5V across the motor with 200 mA current? That sounds like you've connected something wrong or have a faulty transistor. You should be comparing the base current with the collector current, not the emitter current. If everything is connected properly and all the base current is coming out...
  18. KrisBlueNZ

    How Checksum is Calculated in MPLAB v8.76 ?

    I can't tell you how any particular program calculates the checksum, but it's not going to be complicated. If it's an 8-bit checksum, it's usually the bottom eight bits of the sum of the data bytes. If it's a 16-bit checksum, or a 12-bit or 14-bit checksum in the case of a PIC, it's probably the...
  19. KrisBlueNZ

    How does a vaporizer actually work?

    LOL :-)
  20. KrisBlueNZ

    fetching and executing instruction?

    vead, I don't understand what you're trying to do. I think I remember a while ago you said you wanted to design a processor core. Is that what you want to do? You seem to have the general idea of how to read I/O ports, and how the CPU/MCU core executes instructions. You didn't ask any question...
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