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  1. KrisBlueNZ

    Interference in video switching circuitry

    A composite video signal has a specific form. Here's a good example I found at web.onetel.net.uk: This is how a typical video signal looks on an oscilloscope. The section in the middle is one "line" of video, which corresponds to a line of the raster on the screen, as it is scanned from left...
  2. KrisBlueNZ

    What is the frequency of IR2155 in this circuit?

    I get the same answer using those values, but that first schematic is not using the oscillator in the simple way that's shown in the second schematic, which is the design that the formula applies to. The IR2155 data sheet doesn't say much about the oscillator, but it does include an equivalent...
  3. KrisBlueNZ

    Another Heathkit IP20 power supply repair

    Have you downloaded all of the information linked in the other IP-20 repair thread? There's an assembly manual and a separate schematic file. What's the circuit reference of the capacitor that's smoking?
  4. KrisBlueNZ

    Another Heathkit IP20 power supply repair

    Hi Darko and welcome to Electronics Point :-) This is a new project so it should go in a new thread, not in mrmodify's thread. I will move these two posts to a new thread. Please look in the Electronics Repair forum for the new thread and 'subscribe' to it by clicking Watch Thread. I will...
  5. KrisBlueNZ

    Interference in video switching circuitry

    OK, that's a good start. Although I agree a white background would be better. For the video signals, what are the DC voltages of sync, black, and 100% white, relative to GND? What is your VCC rail voltage? Do you have an oscilloscope? If so, please upload a capture of a line of video from a...
  6. KrisBlueNZ

    Interference in video switching circuitry

    Hi there and welcome to Electronics Point :) Diodes are not the answer as Dave said. My guess is that the white level of your signals is exceeding some limit - possibly, exceeding the power supply rails of the switches - and this is interfering with other parts of the circuit. Post a schematic...
  7. KrisBlueNZ

    Microcontroller controlled by pushbutton for LED flashlight

    You could graph the voltage vs. current behaviour of a driver using two multimeters and a variable power supply. This will not show the dynamic behaviour due to the reservoir capacitor inside the driver, but I think it would be interesting, and would be enough to prove that the LED driver's...
  8. KrisBlueNZ

    Microcontroller controlled by pushbutton for LED flashlight

    OK, so that "driver" really does nothing except provide dimming and flashing options, and some poorly controlled current limiting. The voltage vs. current graph won't be a simple 0.5V drop (I guess you assumed that from the presence of the diode) and you can't rely on it to provide enough...
  9. KrisBlueNZ

    10 bit Parallel-in Serial-out Shift Register

    You already have serial output; all you need is parallel input. A simple way to add parallel input is to use the set and reset inputs of the flip-flops. You need to add a single parallel load signal, and a parallel data input for each flip-flop. Your logic needs to take these input signals and...
  10. KrisBlueNZ

    Microcontroller controlled by pushbutton for LED flashlight

    I think Electronics Point says you're offline if you haven't accessed the site for a certain amount of time, not if you're disconnected from the net. OK. I'm not happy with the amount of detail you're providing about the LEDs and drivers. I think you may have to restrict the application of your...
  11. KrisBlueNZ

    Microcontroller controlled by pushbutton for LED flashlight

    OK. Can you give us some detail on the LEDs. Data sheet references? Forward voltages? How many? All in parallel? Individual current limiting resistors? Total operating current 5A maximum, right? I was asking what you're using the LED driver for because if it just provides current limiting, you...
  12. KrisBlueNZ

    Microcontroller controlled by pushbutton for LED flashlight

    OK, what does that LED "driver" actually do, apart from providing flashing modes and varying the brightness using PWM? It doesn't have any inductors, so it doesn't boost the voltage. Does it provide current limiting? What are you using it for? What kind of LEDs do you intend to use with it...
  13. KrisBlueNZ

    Microcontroller controlled by pushbutton for LED flashlight

    OK, tell us about the LED drivers. Part numbers, data sheet references. And what kind of batteries will you be using? That's what I mean about telling us everything you can about the project - not just what you think is relevant - and giving us as much detail as possible.
  14. KrisBlueNZ

    Microcontroller controlled by pushbutton for LED flashlight

    Obviously. My point is, how do you know you've now thought of everything we need to know? OK. How about pulsing the LED OFF for a very short time - too short to be visible - a millisecond, say - at regular intervals, for example once per second, to maintain the charge on a smallish capacitor...
  15. KrisBlueNZ

    Microcontroller controlled by pushbutton for LED flashlight

    LOL yes it is, and yes I do, but at random times. I'm unemployed and my sleeping patterns are more like sleeping scribbles :-/
  16. KrisBlueNZ

    10 bit Parallel-in Serial-out Shift Register

    The bottom end of S1B is connected to earth! I don't know if that's why it isn't working, but it's wrong, so try fixing it! Edit: Also, S3 is currently shorting VCC to earth as well.
  17. KrisBlueNZ

    Microcontroller controlled by pushbutton for LED flashlight

    It's good that you've realised that you should have told us more about the project, but I think you need to carry that idea further. You've told us about the problem you've just discovered, but you're assuming that's the only one. That's a natural assumption, and it may be right, but it might...
  18. KrisBlueNZ

    10 bit Parallel-in Serial-out Shift Register

    What is the basic logic element that makes up a shift register? How are they connected together to provide parallel input, serial input, shifting operation, parallel output, and serial output? When you're creating a new device in a simulator or using an FPGA, it's helpful to look at existing...
  19. KrisBlueNZ

    Hello, world!

    Hi there Kyle and welcome to Electronics Point :-) You and chopnhack should become good friends then. He is a woodworker (among many talents) as well. Where in the US are you located?
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