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  1. BobK

    Need 1000v??

    Look up "Boost converter". This will tell you how to create a high DC voltage from a low one. Bob
  2. BobK

    Need 1000v??

    Yes, connect 111 of them in series. Bob
  3. BobK

    How to generate 22V pulses from TTL and a 22V supply

    50ma is a lot of current. You can't use the simplest (single transistor) version for that. For example, if you used a 100R resistor, that would drop 5V at 50ma. So you would need a level shifter followed by a push-pull pair. To make this out of discrete transistors it would be difficult to...
  4. BobK

    How to generate 22V pulses from TTL and a 22V supply

    And how fast does it need to switch? Bob
  5. BobK

    How to generate 22V pulses from TTL and a 22V supply

    You need a level shifter. Depending on the current you need out, this can be as simple as an NPN with the emitter to ground, the collector to a resistor to 22V and the base to a resistor to the TTL signal. If you need to source significant current, you will need to follow this with a PNP high...
  6. BobK

    Please help me in audio circuit

    Look up ADC (analog to digital converter) and DAC (digital to analog converter). Bob
  7. BobK

    Collective Components

    A race of relays A network of cables An art o' chokes
  8. BobK

    Collective Components

    A loony farm of bipolar transistors. Acres or hectares of field effect transistors. A bed of MOSFETS.
  9. BobK

    1/4-inch-to-1/8-inch plug adapter

    If you have junk cables lying around, sure, just cut them and solder the wires together and wrap them in tape or heat shrink if that is available. The guitar cable is likely to be coaxial and the headphone cable not. Cut the guitar cable long and the headphone one short to minimize stray...
  10. BobK

    L.E.D Setup to 800w Amp

    The most foolproof way would be to drive the LEDs from a separate battery instead of deriving the power for them from the speaker output. You should be able to find circuits for this on the web. Then, if you only have the speaker output, instead of a line level output to drive the LED circuit...
  11. BobK

    Power handling limits of resistors

    As long as the resistance is the same, they would divide the voltage equally and again, the power would be divided equally and hence the total power would just add up. On the other hand, if you used different value resistors, either in parallel or in series they would divide the power...
  12. BobK

    LED driver chip question

    The chip can dissapate at least 1.7 W depending on the package you are using. At 20ma per LED, that is 320 ma. Dropping a full 2V will only dissapate 0.64 W, less that half the chip is capable of, so I don't see how you would need to drop the voltage externally. If you were trying to drive...
  13. BobK

    Power handling limits of resistors

    Yes, paralleling resistors with the same resistance will add their power handling capability. I don't think the composisiton of a resistor matters as long as the power rating is sufficient. Bob
  14. BobK

    Driving primary isolated mosfets

    You need a high side mosfet driver chip. They supply the voltage above the high side voltage by using a switched capacitor. They are also designed to give a high peak current to the gate. Bob
  15. BobK

    Resistance

    The impedance is not all that important as long as it is not too low. A higher impedance will just mean you cannot get quite as much power out of the amp. If you want to try it, I would put the 3 midranges in parallel, then put this in series with the subwoofer. This would give you 6.2...
  16. BobK

    Voltage Regulator for 30W solar

    It looks reasonable. Any switch mode regulator should be far more efficient than 7805's. Bob
  17. BobK

    Resistance

    The problem is not just the impedance, but the balance of sound. If you just wire them in a combination of series and parallel, you may achieve close the right impedance, but different wirings will give you different frequency respose. The only way to do it right is with a custom designed...
  18. BobK

    Met

    Write a 1ms delay (1000 instructions) then call it 60000 / BPM times for each beat. For example, at 60 BPM you would call it 1000 times to get a 1 second delay. Bob
  19. BobK

    Voltage Regulator for 30W solar

    Using a 7805 to go from 17V to 5V is only 29% efficient. A better solution would be a DC-DC converter. These are much more efficient. You can get them as modules or look for a switch mode regulator and build it yourself. Bob
  20. BobK

    New Power Supply

    Well, that rule of thumb is flawed even for 60Hz. The equation for a capacitor charging / discharging is: I = C dV/dT So setting I to 1 A and C at 1000uF we find that dV/dT is 1000V / sec. With a full bridge rectifier, the capacitor is going to have to supply the current for about 1/4...
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