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  1. KrisBlueNZ

    Designing a Time Delayed Relay

    Ah, I think I see what you're getting at now. In post #15, the red box with the sockets on it represents the thing you want to build, right? It plugs into the 220VAC and 110VAC supplies using two plugs on power cables at the left. And the two motors plug into the two sockets on the front...
  2. KrisBlueNZ

    Desoldering Grief

    RoHS-compliant boards use lead-free solder which has a higher melting point than standard solder. Multi-layer boards have high thermal mass and it is difficult to heat up the pads under large components because the heat travels to the inner layers very quickly. Sometimes, the glue that...
  3. KrisBlueNZ

    Next/previous switching a multiplexer

    Yes; that looks good. On each debouncing circuit, I recommend adding a resistor between the resistor-and-pushbutton node and the capacitor-and-gate-input node. You have the right polarity for the CLOCK DOWN and CLOCK UP signals - the 40193 increments on the rising edge, which corresponds to...
  4. KrisBlueNZ

    PSU Sugestions

    I don't think those ICs are NJU7001. The NJU7001 is the single op-amp version in an 8-pin package; those are 14-pin packages which are most likely quad op-amps. I looked on the jrc.com website and couldn't find anything else with 7001 in it, so I don't know what that IC is, but it sounds like...
  5. KrisBlueNZ

    Connecting 12v dc motor to a rc circuit car

    Yes, exactly. Assuming both motors need to be able to be driven in both directions.
  6. KrisBlueNZ

    Adjustable Hz flashing lights

    Are they LEDs or light bulbs? Do you have a manufacturer and part number for them?
  7. KrisBlueNZ

    Next/previous switching a multiplexer

    You need a 4-bit binary (not BCD) up-down counter. Check out these possibilities: CD4029: http://www.digikey.com/product-detail/en/CD4029BE/296-2046-5-ND/67275 Presettable (loadable); separate up/down and clock CD4516: http://www.digikey.com/product-detail/en/CD4516BE/296-2075-5-ND/67349...
  8. KrisBlueNZ

    high pass rc circuit .

    A high-pass filter is a frequency-dependent attenuator. A simple one-pole high-pass filter consists of a series capacitor, followed by a resistor to ground. This configuration forms a kind of voltage divider, where the output amplitude is determined by the ratio between the "top" resistance (the...
  9. KrisBlueNZ

    Need help with remote firework detonator

    Good idea KJ6EAD. CTCSS plus DTMF would be fairly reliable. Good thinking.
  10. KrisBlueNZ

    Motion sensor lighting with a difference

    Hi David and welcome to Electronics Point :) Thanks for the nice clear explanation. So you have a PIR sensor that you want to be able to use to control some LED strip lighting. You want to be able to wave near the PIR sensor to turn the LEDs ON, and wave again to turn them OFF, and you want...
  11. KrisBlueNZ

    voltage and current

    Adobe Premier is a video editing program. I don't see how it would be helpful at all. I mentioned Adobe Audition, which is similar to Audacity. Matlab is probably more appropriate than both Audition and Audacity.
  12. KrisBlueNZ

    Need of a common ground???

    Yes. I would expect they would already be connected. The transistor responds to current from the PIC that enters the base and comes out the emitter. The transistor switches current that comes in the collector and out the emitter. The emitter is the common point for those two currents, hence the...
  13. KrisBlueNZ

    "Boom Box" question

    Don't use any resistors to change the impedance; it will just waste power. Find an amplifier that's designed to drive those impedances. They're not unusual. Google audio amplifier kitset - there are several out there.
  14. KrisBlueNZ

    Pic 16f877a anlog input error

    What VRef voltage are you using? Are you feeding signals into the ADC that are higher than VRef? Have you disabled analogue input functions on the other I/O pins? You should definitely do that if you're using the other ADC-capable pins as digital I/O.
  15. KrisBlueNZ

    voltage and current

    I'm glad you like it. It's not MY software though! I don't even use it. I use Adobe Audition, which is really just Cool Edit Pro in disguise. Now THAT's a nice piece of software.
  16. KrisBlueNZ

    voltage and current

    You're using simulation software to connect an AC voltage source across a resistor? If not, please post a schematic so I know what you mean. If you connect an oscilloscope across the resistor, you will see the voltage from the voltage source. If you want to see the waveform of the current in...
  17. KrisBlueNZ

    voltage and current

    In an ideal resistor, voltage and current are always exactly proportional. They are related by a constant, R, the resistance of the resistor, according to Ohm's Law: I = V / R. If R is constant (as it is for an ideal resistor), Ohm's Law tells you that current and voltage are directly...
  18. KrisBlueNZ

    Question about fuses

    I Googled those markings and discovered that the fuse is made by http://www.socfuse.com and the data sheet is at http://www.socfuse.com/products/pdf/P90_E.pdf The CES is a 0.25x1.25" (3AB/3AG) ceramic cartridge fuse, described as "inrush withstanding", which I guess is similar to, or the same...
  19. KrisBlueNZ

    Super Capacitor\Cell Battery Voltage meter

    Operation down to 1V is the special feature you need. Linear Technology have several possibilities. Listed in order of increasing price: http://www.linear.com/product/LT1610 http://www.linear.com/product/LT1613 http://www.linear.com/product/LT1307 http://www.linear.com/product/LTC3122...
  20. KrisBlueNZ

    circuit design

    That's interesting Bob. I don't think I've heard of that before. I don't think about the aesthetics of the big picture. I'm careful with things like keeping diodes and electrolytics oriented the same way where possible, and avoiding burying small components among tall components. Weight balance...
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