Search results

  1. KrisBlueNZ

    What is the frequency of IR2155 in this circuit?

    OK, in that design, the oscillator in IC2 (pins 2 and 3) is used slightly differently from normal, but during the multi-spark period, as explained in the section titled "Multi-sparking", its frequency is determined by the 4.7 nF capacitor and the two resistors from pin 2, as per the data sheet...
  2. KrisBlueNZ

    Should wire be Twisted before Crimping?

    Thanks Xilef. That explanation sounds reasonable to me. Edit: And welcome to Electronics Point :-) Please feel free to introduce yourself on the introductions thread in the introductions forum!
  3. KrisBlueNZ

    Embedded device driver

    A device driver in an embedded system is the same as a device driver in other environments. It's a code module that provides support for a specific piece of hardware and provides standardised support for that hardware. For example, an embedded system might include a display. The display...
  4. KrisBlueNZ

    Should wire be Twisted before Crimping?

    Maybe I was wrong. Based on my experience, crimping grips the wire a lot better when it's twisted. That' my rationale. Do you know the rationale for why they shouldn't be twisted? I'd like to hear others' opinions too.
  5. KrisBlueNZ

    AC/DC Power Convert Questions

    Agreed. I missed that in Dave's post. AFAIK ferrules or crimp connectors are preferred (around tightly twisted strands); otherwise, twist tightly, double the wire back on itself or loop it round the screw, and screw the washer down, without using solder. Edit: I'm probably wrong about twisting...
  6. KrisBlueNZ

    AC/DC Power Convert Questions

    Good answer there from Dave. Re your other questions: According to the sales page for that power supply, the output can be adjusted by ±10% which is a range of 25.2~30.8V. If you want a separate 5V rail you should use a second power supply fed from that one. This can be a non-isolated buck...
  7. KrisBlueNZ

    transistor switching question

    If you mean a 2N2222, then yes. Active high. A high level on the Arduino output will make the first transistor conduct, which will make the second transistor conduct, which will present +12V on the common anode of the display. Not really. If you connected +5V to the base of TIP32, and...
  8. KrisBlueNZ

    Microcontroller controlled by pushbutton for LED flashlight

    Without doing any calculations, I'd suggest you try a 10 µF smoothing capacitor between VDD and 0V (to run the micro and provide gate bias for the MOSFET) and a resistor of around 33Ω. But you can't really test how the switching will affect the driver unless you have your PIC and your N-channel...
  9. KrisBlueNZ

    a timing circuit

    Check that the 330Ω resistor (in series with the LED) is the correct value. It should be orange-orange-brown, or orange-orange-black-black. Check that there is at least 6V across the 330Ω resistor. If there isn't, you may have connected the LED backwards. Try connecting it the other way and see...
  10. KrisBlueNZ

    Interference in video switching circuitry

    OK, that first trace is good. I can see the 100% white for most of the line, and the sync pulses. Are these captures all from the same source device? I think you have AC coupling enabled on your scope. You need to use DC coupling, and with nothing connected to the scope input, adjust the...
  11. KrisBlueNZ

    weird pots resistance

    I agree with Dave. I haven't seen this before but I'd guess there is a poor connection from the tag, through the rivet, to the end of the carbon track. For example, impurities on the metal, which prevent a proper contact between the rivet and the metal at the end of the copper track. When you...
  12. KrisBlueNZ

    transistor switching question

    Yes, your common anode drive circuit won't work. I can't explain why it worked on the breadboard. You need to use an NPN driving a PNP. The circuit is very common; I found an example at http://www.eevblog.com/forum/beginners/what-ic-to-use-to-convert-ttl-to-24vdc-pnp-output/ which is repeated...
  13. KrisBlueNZ

    Interference in video switching circuitry

    No. If you're concerned about earth loops, insert a low value resistor (e.g. 10~33Ω) in series with the ground connection on all but one cable between your box and each device, and make sure the devices aren't earthed independently, just through your box.
  14. KrisBlueNZ

    What range of frequencies would do this ?

    Sound is vibration. Making your ears pop normally requires a steady and constant change in air pressure, not a brief variation. Extremely low frequencies are sort of part way between the two, but reproducing them requires very large equipment and a lot of power so it couldn't be made hand-held...
  15. KrisBlueNZ

    Interference in video switching circuitry

    You mean the scope leads? Connect the tip of the probe to the video signal at the RCA connector, and clip the earth clip to the 0V rail of the circuit. The "signal negative" (the outer connection of the RCA socket) is already connected to the 0V rail of the circuit. No it's not! Are you...
  16. KrisBlueNZ

    Newbie Arduino questions

    You can disregard that unhelpful post from Bluejets. Bluejets, it's not necessary to try to answer every post - only answering the ones you know about is fine! The "number of bits" tells you something about the complexity and processing power of the processor core. It is the native "word size"...
  17. KrisBlueNZ

    a timing circuit

    Hi Joseph and welcome to Electronics Point :-) That circuit is really badly drawn but it should do something. Let's start by testing the LED/phototransistor section. Set your multimeter to the 20V DC range and connect the red probe to the MOSFET's gate and the black probe to the source. With...
  18. KrisBlueNZ

    Stage Line 500W amp repair project

    OK, there's not enough bias in either of the output stages. I think the resistor fuses might be the cause. Can you temporarily install four low current fuses, e.g. between 100 mA and 500 mA, fast blow, instead of the resistor/LED fuses, and re-measure those voltages please.
  19. KrisBlueNZ

    Power through current sources

    Just trying to clarify... I guess the original circuit can be simplified down to this: Do you agree with that diagram? Then the power dissipated in each current source can be calculated using the Power law, taking into account the direction of current flow. So you guys are assuming that...
  20. KrisBlueNZ

    The input given to Piezo Speaker is an analogue signal or Digital signal?

    What type of "speaker" is it? Is it a simple piezo "bender" like this one? These devices are not really speakers, in that they're not designed to reproduce sounds accurately. They're designed to reproduce beeps, really. Also, what kind of sounds are you generating with the Arduino? Just...
Top