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  1. Hero999

    50V, 50A H-Bridge IC needed

    First check that the schematic is wired as per the attachment below. Check the voltage across each zener is around 10V. You might need to reduce the values of R2 and R4 slightly to ensure the zener current is high enough for the zeners to clamp the voltage effectively.
  2. Hero999

    HELP> AC Circuits projects

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  3. Hero999

    50V, 50A H-Bridge IC needed

    The polarity of the zeners needs to be reversed, they won't protect the MOSFETs as they're currently connected. Remember a zener just acts like a normal diode when it's forward biased.
  4. Hero999

    50V, 50A H-Bridge IC needed

    Only D3 and D5 are required. Think about it. The gate voltage for the lower MOSFETs comes from a logic circuit so there's no chance of it exceeding 5V, let alone 20V. The voltage is also only one polarity so there's no need to connect the zeners back-to-back which is only required for AC. D3...
  5. Hero999

    Current Limiting Technique

    What's the capacity and internal resistance of the batteries? You should take it into account because the voltage will probably drop below 12V per battery when the 40A load is applied. I hope you connect a transient suppressor to the coil, other wise an arc will form across a mechanical switch...
  6. Hero999

    Son's school project is this possiable

    It's pretty straightforward. You can buy ICs which can record and playback sound or even simpler, buy a module that does it all for you. http://www.rapidonline.com/sku/Educational-Products/Projects-Robotics/Sound-Music-Light-Modules/10-Second-sound-recorder-playback-module/60530/13-0678
  7. Hero999

    intercomm

    No but we are willing to help you design the circuit yourself. Anyway, you haven't provided enough information.
  8. Hero999

    opamp roll-off

    But some of his posts are wrong and might confuse a newb into believing incorrect information.
  9. Hero999

    opamp roll-off

    Thanks, I've found the datasheet and saved it, here's a link. http://www.nxp.com/documents/data_sheet/UA741X.pdf
  10. Hero999

    Will this high-current regulator work?

    It used to be complicated but it's fairly straightforward nowadays. Look at the Linear technology, National and Maximum semiconductor websites: they all make SMPS ICs which are fairly easy to use.
  11. Hero999

    opamp roll-off

    Where did you get that graph from? The datasheet I found on Google did not include that graph, although I know I've seen it somewhere before.
  12. Hero999

    Switch selection for high-power H-bridge

    The capacitance is normally only a problem for op-amps and circuits with high output impedance which can limit the switching time. If all the MOSFETs parrallel have a combined capacitance of 50nF and the output resistance of the logic circuit and gate resistor is 500R the time constant will be 25
  13. Hero999

    Will this high-current regulator work?

    It's not possible to have a linear regulator with an input current of 4A and the output current is 4.75A. With a linear regulator, the output current is always equal or lower than the input current. You need to use a switched mode power supply if you want to reduce the voltage but boost the...
  14. Hero999

    opamp roll-off

    I'll answer in case a newb reads this and gets confused. . . Where did you get your information from? I couldn't find a frequency response graph on the datasheet. You couldn't be right or wrong, either way it's not an acceptable design because the slew rate limits the output voltage to an...
  15. Hero999

    50V, 50A H-Bridge IC needed

    The high side MOSFETs will dissipate more power because they are P-channel and will have a higher on resistance. two 9V batteries in series driving a 54R load is not 18V because the batteries are overloaded the voltage will drop to around 14V. I don't know why the MOSFETs blew when it was...
  16. Hero999

    Switch selection for high-power H-bridge

    72W power loss isn't too bad, it's 98.8% efficient which is quite good. You can buy 150V MOSFETS with a resistance of 16mΩ which will gut the loss to just 51.2W but you'll need a way of driving the high side gates above 150V. http://www.fairchildsemi.com/ds/FD/FDB2532.pdf A simpler solution is...
  17. Hero999

    Switch selection for high-power H-bridge

    I would probably suggest MOSFETs. Is there any DC? If it's AC only, then you could use a pulse transformers to control the high side, rather than N-channel MOSFETs, which will loose less voltage. I can't think of any other solutions than MOSFETs or IBGTs but at 150V, the former is probably...
  18. Hero999

    Free and open source electronic applications

    Wow, it actually appears to be genuine. At first I thought this was spam but it seems to be genuine. I'll download it, virus scan it and install it.
  19. Hero999

    a light dependent switch

    No one's going to email you, we only help on the open forum. Here are a few circuits: http://www.silicontronics.com/index.php?action=ezportal;sa=page;p=17
  20. Hero999

    tv

    You might get a better response if you tell us the make and model.
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