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  1. KrisBlueNZ

    5 Digit Digital stop watch using a MC14553b and TIL 311

    I don't think you'll be able to use the MC14553 because there's no easy way to make it reset at 60. It contains three BCD counters and counts up to 999, and the counter outputs are not all available simultaneously - it uses a multiplexed output. It's a specialised part with limited usefulness...
  2. KrisBlueNZ

    Low Voltage protection (cut at 33v - Full charged 44v)

    That's an interesting page you found there Steve. Despite the claims in the text, that circuit doesn't have hysteresis. There is an emitter degeneration resistor that provides negative feedback, but no positive feedback. Just another example of circuits that don't really work, presented on the...
  3. KrisBlueNZ

    Programming Help

    I can't help much here, since I have no experience with PICs, but for measuring intervals, it's more usual (and more accurate) to use an input capture peripheral, as described in section 15 of the data sheet.
  4. KrisBlueNZ

    Switch on load only when alternator is running?

    Changes for 24V operation: 1. D1 change to 1N4004 2. K1 change to a relay with a 24V coil such as Omron G5LE-1A(4)EDC24 (10A contacts), see http://www.digikey.com/product-detail/en/G5LE-1A4%20DC24/Z2254-ND/369017 3. R1 change to 56k 4. R2 no change (hysteresis will now be about 0.4V) 5. R3 no...
  5. KrisBlueNZ

    Tv ir receiver

    The multimeter will respond to the average DC voltage across the current shunt that is in series with the LED strip. (This current shunt is inside the multimeter if you use it on a current range.) It should be fairly accurate.
  6. KrisBlueNZ

    Bottleneck 555's 0.2A Stuck project

    Re how to connect the Schottky diode: it has an anode and a cathode just like any diode. One of the leads is either not connected, or a duplicate of one of the other leads. Look at the data sheet! You need to use heavy wire all the way from the motor positive to the battery positive, and from...
  7. KrisBlueNZ

    Tv ir receiver

    I don't think so. It depends on exactly how the control boards works. Try swapping the LED strips and see whether the delayed dimming follows the LED strip or stays with the same control board. That wouldn't be very accurate. The amount of power used by the power supply and the control board...
  8. KrisBlueNZ

    2 Channel timer project

    Here's a circuit that should do what you want. Here's a circuit description. The circuit requires a 12V DC power supply. Current consumption will be 500 mA maximum so I recommend a power supply rated for 1A. SW2 is a normally closed pushbutton for Emergency Stop. Pressing it breaks the...
  9. KrisBlueNZ

    Battery powered Current sink with low voltage cutoff

    You would have 3.45 mA flowing in the 1K resistor. Most of that current flows into the TL431 to allow it to regulate. A small amount of it flows into the potentiometers and the voltage-setting resistors. I've Googled that part number and found it for sale, but I didn't find any data sheet. If...
  10. KrisBlueNZ

    Bottleneck 555's 0.2A Stuck project

    The VDSS voltage specification is the maximum voltage it is specified to withstand. Thanks for the links. That makes it easier for me to help you. Yes, the IRF2804 is perfect for this project. It will dissipate almost no power at all, as long as it is switched ON and OFF quickly and fully...
  11. KrisBlueNZ

    Tv ir receiver

    You could buffer the receiver output but I doubt very much that it would help. Yes, you could use a CD4050, or perhaps a PNP emitter follower. I won't draw a diagram unless you (Mustwin351) really want to try it, because I don't think it would help.
  12. KrisBlueNZ

    Tv ir receiver

    Bzzt! I would expect them both to behave the same, because all timing should be controlled by the 24 MHz crystal. I don't know why one would fade out more slowly than the other. But it's not because of wire lengths (unless the wires are thousands of miles long!)
  13. KrisBlueNZ

    Bottleneck 555's 0.2A Stuck project

    I just searched for MOSFET on eBay and found several suitable devices on the first page of the results, in quantities from 2 to 10 and prices from USD 4 to USD 15.
  14. KrisBlueNZ

    Adc of atmega32

    OK, good. The analogue circuitry should be grounded to an AGND rail, which should be kept separate from the circuit's main GND rail. At a single point, connect together the AGND rail, both of the MCU's GND pins (using short wires) (you don't need to bring the two GND pins to the single point...
  15. KrisBlueNZ

    Battery powered Current sink with low voltage cutoff

    What do you mean that we're drawing 4~5 mA now? There are three loads on the 8V reference voltage rail, and none of them draws more than 0.5 mA. Re the pots, to my knowledge they should never go open circuit, so I would regard it as a fault. Do you have a manufacturer and part number, or a link...
  16. KrisBlueNZ

    Battery powered Current sink with low voltage cutoff

    I'm not sure what you're asking. Do you mean that if you draw 3~8 mA of current from the 8V reference rail, it will drop down to 3~5V? Yes, that's true. No part of the circuit is supposed to draw significant current from the 8V reference rail. The three resistive loads (the two potentiometers...
  17. KrisBlueNZ

    Battery powered Current sink with low voltage cutoff

    I'm not very happy with your construction. I think you should redesign the layout on paper first, and aim to keep the component leads short and the axial components mostly oriented the same way; that is, perpendicular to the tracks. You may find it helpful to concentrate on components that are...
  18. KrisBlueNZ

    Adc of atmega32

    Yes, as Steve said, it depends on what kind of signals they are. If they are unipolar voltages, i.e. one wire is always positive relative to the other, then you can connect the negative wires to AGND. If the signal is bipolar, i.e. an AC voltage, you may be able to connect the return wires to an...
  19. KrisBlueNZ

    SAM3N00B micro repeated reset = OK?

    As an embedded systems designer and programmer, I would consider a situation where the microcontroller is repeatedly powered up and powered down to be a major issue. Certainly it won't damage the microcontroller but that kind of behaviour is totally unacceptable in an embedded system. It seems...
  20. KrisBlueNZ

    Tv ir receiver

    OK, thanks for the picture. Without a schematic, I can't say for sure that it would be possible to control two boards from the microcontroller on one board. It may be possible but it may not be. My only suggestion now is for you to find someone with electronics experience who can trace out the...
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