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  1. Hero999

    Design new 0 to 30V power supply.

    I'd probably use a comparator with an open collector output and a temperature sensor at the input. When the temperature exceeds a certain threshold the gate signal to M2 to M4 will be clamped to 0V, by the comparator, shutting the regulator down. Another comparator could be used to switch the...
  2. Hero999

    Integrated circuits

    Care to name the IC in question? You should have done that in the first post.
  3. Hero999

    Integrated circuits

    The schematic can often be found on the datasheet but it's normally in a simplified form.
  4. Hero999

    Simple, in-line volume control

    Use a small 120V variac? Probably not ideal but better than a series resistor.
  5. Hero999

    Which software should I use.

    Use code tags for the program code and avoid block capitals. I'm no expert when it comes to programming or micro controllers so maybe someone else here can help you?
  6. Hero999

    Design new 0 to 30V power supply.

    Using the MCU to turn the fan on and off would be a very bad idea unless you can ensure that it will fail safe i.e. if the software fails, the fan will stay on. The same applies to thermal shut down, although software controlled thermal shut down is still better than no thermal shut down...
  7. Hero999

    Temp sensor to turn on relay to fan

    A simple comparator circuit will do, I'd recommend the LM311, read the following : http://home.cogeco.ca/~rpaisley4/Comparators.html http://www.silicontronics.com/index.php?action=ezportal;sa=page;p=17
  8. Hero999

    74188, 74287, 74288, 74387

    They're probably obsolete. Try searching for the LS or HC equivalents i.e 74HC188 or 74LS188, no one uses TTL any more, it's inferior and more expensive as it's not made any more. I remember looking for the 7400 at Maplin and noticed how much more expensive it was than the 74LS00 and that was...
  9. Hero999

    Simple FM transmitter question/s + help

    It won't make any difference if you use 5pF rather than 5.6pF the capacitor probably has a 10% tolerance anyway. How have you built the circuit? Is it on a bread board? Does it have long wires? It should be on a stripboard or PCB and the connections should be as compact as possible. The...
  10. Hero999

    Final stage amplifier

    That's got nothing to do with an IC being used rather than discretes for the output stage and all to do with the overly optimistic claims made on the datasheets. If the power is kept low enough then there will be no more clipping and distortion than a transistor amplifier. I know you know this...
  11. Hero999

    sony defects how to solve

    Sorry but your post doesn't make much sense: this is an English forum. I think you've confused this place for a similar Filipino forum.
  12. Hero999

    help me plz...for my project study..

    Please provide more information and try to write using correct spelling punctuation and grammar.
  13. Hero999

    Design new 0 to 30V power supply.

    The physical size of the heat sink doesn't matter, as long as the
  14. Hero999

    Design new 0 to 30V power supply.

    I've finished the design. Attached is the BoM and the schematic. One thing you'll notice is it needs an insanely large heat sink <55
  15. Hero999

    Design new 0 to 30V power supply.

    I'll get the final parts list and schematic finished tomorrow. I'm still not sure it even needs the negative supply, I know LTSpice didn't like it without it but that doesn't mean anything. I'll include it on the schematic and ask whoever builds it to try connecting it to 0V to see if it still...
  16. Hero999

    Design new 0 to 30V power supply.

    20mA means I could happily remove the booster transistor or do you think that would be a bad idea? Here's the latest schematic, I've added the current delay in. I'll probably precede to the final version and the BoM soon. I'm not going to worry about getting exactly the right models for the...
  17. Hero999

    Help needed urgently: Audio Amplifier Project.

    The idle current is the current drawn when no sound is produced. For low distortion the circuit needs to be operating in class A-B which occurs when both Q5 and Q6 are conducting slightly when there's no signal. Adjusting RV2 alters the base voltage of Q5 and Q6 and thus the idle current. The...
  18. Hero999

    Design new 0 to 30V power supply.

    Don't forget that the higher the current the larger the transistor and heat sink needs to be. I would like to use the same heatsink as used for the MOSFET but I don't want to use long leads for a voltage reference. I'll rate the reference power supply to 250mA for now which will allow a cheap...
  19. Hero999

    Design new 0 to 30V power supply.

    It's slightly more expensive to buy two 10,000
  20. Hero999

    Adding a Digital Multimeter LCD to XP-720

    It's difficult to show you without a copy of the original power supply. The 'To +' and 'To -' inputs jusst go to the positive and negative supply outputs respectively. The current sense resistors go in series with the outputs but still enclosed in the feedback loop. I have a feeling that the...
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