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  1. Hero999

    How to generate negative voltage from PIC

    You need a negative supply, even the best rail-to-rail op-amps will only give you 0V, if the negative supply voltage is 0V and there's no load current. The easiest way is to use a buck-boost converter. http://en.wikipedia.org/wiki/Buck
  2. Hero999

    Idiot's guide to transformers ?

    You probably won't be able to buy the Russian rectifier diodes any more. They're almost certainly obsolete and inferior to modern diodes. I'd recommend replacing the old diodes with modern ones, even if they work. If replacing the diodes doesn't work, try replacing all of the electrolytic...
  3. Hero999

    load cell to AD620 op amp, circuit not working, is chip dead?

    Increasing the positive power supply voltage won't make any difference. You need a negative supply voltage, if the input is below 1.9V.
  4. Hero999

    load cell to AD620 op amp, circuit not working, is chip dead?

    I think the input voltages are out of range. The chip only works when the inputs are 1.9V above the negative supply and 1.2V below the positive supply.
  5. Hero999

    Protect Electronics from very low and very high temperature

    You need a heater to warm the board to -40 before most components will work.
  6. Hero999

    12.6v DC LED Flashers??? Need wiring help!

    There are all sorts of ways of making the patten generator, here's one idea. The LEDs will need to be driven using transistors and you'll need an LM7805 for the 74HC132. Where did you get 32V from? The highest voltage in the circuit is 12V. You can buy sirens from various suppliers.
  7. Hero999

    H-bridge using only n-channel mosfets

    Yes, just swap the IGBTs for MOSFETs but if it's HV IGBTs are probably better.
  8. Hero999

    Linear response

    Yes, you seem to be talking nonsense Kevin. How about posting a schematic so we know what you're on about?
  9. Hero999

    Is modification needed to dc motor controller?

    What do you think?
  10. Hero999

    RC CAR

    Please don't bump old threads, the original poster has probably disappeared, check the date before posting.
  11. Hero999

    555 Toggle On / OFF Switch

    I don't know what you're talking about as far as the transistor is concerned or why you still can't use the CD4013 or omit the transistor and connect the relay between pin 3 and 0V. All silicon transistors have a base voltage of between 0.6V and 1V depending on the base current. If anything...
  12. Hero999

    3-Axis Stepper Controller

    Thanks. That's the trouble with linking to external sites. I've zipped all the files and attached them to this post. Unfortunately there's still no guarantee it will stay here forever, as attachments have been lost before when the site has crashed and been restored in the past. If anyone has...
  13. Hero999

    555 Toggle On / OFF Switch

    No, just  connect it up and it will work. T1 isn't needed though, the relay can be connected directly between pin 3 and 0V but you still need D1 to protect the 555 from back-EMF. By the way, you do realise there are lots of better ways to make this circuit? Are you planning to leave it...
  14. Hero999

    Buck converter with SG3524 and IR2117, problem with duty cycle.

    Yes we need the schematic and please attach it rather than uploading it to some image hosting site, click additional options, choose, select the file and click open.
  15. Hero999

    how to design a microprocessor

    Then you start with a simpler project such as designing a 4-bit processor.
  16. Hero999

    Is my Li-Ion bicycle light battery repairable?

    That sounds like a rip-off. Unfortunately, Li-ion cells are dangerous to recharge, if the cell voltage has dropped below a certain lavel, 2.5V springs to mind. You're better off seeing if you can buy similar cells for cheaper. Be warned that there's often a protection system built-into the...
  17. Hero999

    Where are some applications of disc shaped heatsinks?

    The link doesn't work. If you want to post a picture then attach it, click additional options, choose, select the file and click open.
  18. Hero999

    Automatic Fan Controller - Help (w/ relay?) Please!

    I made a typo but yes, both the IRL520 and IRF520 have a high on resistance for MOSFETs. The difference between the IRL and IRF devices is the L devices are logic level, meaning they will pass the full current with a drain voltage of just 4.5V, the F devices require between 7V and 10V before...
  19. Hero999

    Automatic Fan Controller - Help (w/ relay?) Please!

    Yes that would work, although I'd recommend making a few modifications: 1) Get rid of the 470uF capacitor across the MOSFET, it doesn't do any good and just reduces the efficiency. 2) Connect the MOSFET's gate to pin 3 which is a push-pull output and is better at driving a MOSFET than pin 7...
  20. Hero999

    Driving Pattern Module ( guide the driver )

    Post in English and you might receive some help.
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