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  1. KrisBlueNZ

    problem with crt lg tv

    Here's the field output stage: The output chip, IC301, is type OIPRP00741A and I can't find any information on it. I would suspect IC301 first. Let the set warm up and when the fault shows up, spray IC301's heatsink with aerosol rapid freeze for a few seconds and watch to see whether the...
  2. KrisBlueNZ

    Next/previous switching a multiplexer

    Yes, that's the important factor. I'm sorry, I don't understand the question. Can you post schematics of the circuits involved? You don't need optocouplers unless you need isolation between the 0V rails of the two circuits. Here's how to use the pulse stretchers without isolation, assuming...
  3. KrisBlueNZ

    ADC on PIC 12F1840 with inconsistent readings

    An error of 0.05V when measuring with a full scale of 12.9V is only 0.4% which is well within the expected tolerance when you're calculating the difference between voltages coming from two independent voltage dividers made with 1% resistors. And that's without even considering the error in VREF...
  4. KrisBlueNZ

    Help with replacement for a rotary switch

    No it won't; if anything, it will prevent changes to the sound. The inputs and outputs of analogue switches will always have some DC level. For best performance with the 4066, this DC level should be half way between VDD and VSS (unless the data sheet specifies otherwise). You can do this by...
  5. KrisBlueNZ

    Help with diagnosing problem with pcb from charge controller

    www.irf.com/product-info/datasheets/data/irfs4410.pdf N-channel MOSFET; 100V, 96A. RDS(on) typically 8 milliohms; maximum 10 milliohms, at VGS=10V. Applications: High Efficiency Synchronous Rectification in SMPS Uninterruptible Power Supply High Speed Power Switching Hard Switched and High...
  6. KrisBlueNZ

    ADC on PIC 12F1840 with inconsistent readings

    Start by posting a circuit and the relevant sections of code (ADC initialisation, ADC reading, and calculations).
  7. KrisBlueNZ

    Help me understand my wall wart

    It's amazing what you can dig up with a bit of Googling! http://www.extremetech.com/computing/115251-how-usb-charging-works-or-how-to-avoid-blowing-up-your-smartphone http://en.wikipedia.org/wiki/USB_Battery_Charging_Specification#Charging_ports...
  8. KrisBlueNZ

    Designing a Time Delayed Relay

    Re your layout in post #64. Change the track from the relay's common pin so it runs directly upwards (under the relay) to the connector. The two coil tracks can then come straight out the bottom. The normally closed pin is not connected but can be connected to the common pin to ease the...
  9. KrisBlueNZ

    Audio poweramp TDA2003

    It's rated for 2x 10V AC at 0.7A? Put the two secondaries in parallel (make sure they're in phase) and feed them through a 3A bridge rectifier into at least 4700 µF of smoothing. You'll get around 12~15V DC under slight load, dropping a few volts under heavy load. With a single TDA2003A you'll...
  10. KrisBlueNZ

    Audio poweramp TDA2003

    You can't use a ±12V or ±10V power supply. Check out the maximum supply voltage for the TDA2003A. This is from the data sheet. You should be able to find a switching power supply that can run from 100 VAC and produce 18V at 2~3A. A switching supply is not the simple kind of power supply that...
  11. KrisBlueNZ

    electronics revision help

    It's not fair to test you on stuff you haven't been taught...
  12. KrisBlueNZ

    Audio poweramp TDA2003

    Ignore anything you read on circuitstoday. If you haven't already, download and read the manufacturer's data sheet: http://www.st.com/web/en/resource/technical/document/datasheet/DM00028077.pdf. With a 12V DC supply into a 4 ohm load, the maximum output power is only 4W. Into an 8 ohm load it...
  13. KrisBlueNZ

    Audio poweramp TDA2003

    Is that text on circuitstoday.com? If so, I'd just ignore it. But you will need a heatsin (actually, a heatsink might be better). I would stick with the design that the manufacturer recommends.
  14. KrisBlueNZ

    Audio poweramp TDA2003

    Based on prior experience I wouldn't trust any design from circuitstoday.com, but in this case this one is copied directly from the manufacturer's data sheet: Yes, the 100 µF and 100 nF capacitors at the top are decoupling capacitors. The 100 nF one should be a ceramic capacitor and should...
  15. KrisBlueNZ

    Small Circuit needed for New Product Design - Help!

    You need decoupling capacitors no matter what. They connect across the power supply rail and are needed for reliable operation of the micro. Normally, a 0.1 µF MLCC (multi-layer ceramic capacitor) right next to the micro, and a small electrolytic (e.g. 10 µF) across the battery, would be...
  16. KrisBlueNZ

    Designing a Time Delayed Relay

    I meant the via size, not the hole size! Cool. Does Seeed Studios have a FAQ to advise you what software they support and recommend? And what settings to use? 16 thou is fine for the signal tracks, but the high-current connections to the relay contact should be as fat as possible, i.e. fills...
  17. KrisBlueNZ

    How many DC volts for power supply?

    I did a web search and most of the hits were you asking this same question on Yahoo Answers. So this is a radio receiver or a preamp or what? Start by uploading some pictures. See https://www.electronicspoint.com/resources/how-to-take-photos-of-circuit-boards.6/ Add markings showing where you...
  18. KrisBlueNZ

    ATX power supply to bench lab supply? help

    http://lmgtfy.com/?q=convert+PC+power+supply+to+bench+supply
  19. KrisBlueNZ

    Help with replacement for a rotary switch

    Yes, power the 4066es with 12V (or 15V if it's well-regulated and will never go much higher) and bias the signals on both sides of the switches at half supply voltage. This gives you the highest allowable signal amplitude, and having all points biased from a single half-supply rail means you...
  20. KrisBlueNZ

    electronics revision help

    That's good. Bridge rectifiers are usually named BRx not Bx. Bx is not normally used. R2's bottom end is shown connected to the GND symbol but there is no junction with the 0V rail. There should be a junction. Actually it's good practice to avoid drawing wires crossing each other like that...
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