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  1. C

    Pic sine wave inverter H-bridge

    Let me put it this way. I was explaining how to start with sorting out the problem. The first thing to do is convert the square wave to a fairly accurate sine wave and deliver this through the output to see the result. If you don't have a smooth wave you can get a lot of "fighting" in the...
  2. C

    I would like to build tach for a small diesel. magnet, sensor, counter, LED

    That's the most important part of the set-up.
  3. C

    Pic sine wave inverter H-bridge

    To get a sinewave you simply output a square wave to a capacitor via a resistor and then buffer the output to drive a sinewave circuit. Once you have a smooth sinewave you can do something with it.
  4. C

    The BJT as an Amplifier homework question

    Basically you can only get a gain of 56 from the circuit. Applying 50mV to the base really only means the collector voltage can only increase or decrease by a factor of 56 and this allows a max change of 2800mV, if the circuit will allow this rise or fall. It is the ratio of emitter resistor...
  5. C

    I would like to build tach for a small diesel. magnet, sensor, counter, LED

    Please explain your set-up. How are you getting the "30" reading and what is the "coil" in the foreground?
  6. C

    High Power SMD LED Array - Heatsinking

    I took it as white LEDs but red LEDs are much lower at 1.8v to 2.2v or it seems like 2.4v so the dissipation will be less. Gluing them to screws will dissipate the heat better than a PCB. 3 watts on 20mm x 20mm will need a LOT of effective heatsinking. Screws are the only answer and the...
  7. C

    automatic doorbell

    An "Automatic Doorbell" IS a security alarm because the person approaching the door may have no intentions of entering. How many times have you passed a Chemist and the doors automatically open? The 27MHz detector can be designed to detect the presence of a body or touching a plate.
  8. C

    High Power SMD LED Array - Heatsinking

    3.6 x 1 x 12 = 43.2 x0.1 = 4.3 watts Some of the wattage will be released as light but 4 watts on a small board will require nuts and bolts from the LED heatsinks to fins on the back of the board.
  9. C

    automatic doorbell

    Your hand kills the RF when you touch the door or handle. It mainly detects someone trying to get in.
  10. C

    automatic doorbell

    This can all be done with an 8-pin micro and 10 components. The frequency can be anything because the receiver just uses amplitude detection. However you can buy the transducers in a microcontroller module for less than the cost of the individual items. A 27MHz version would be cheaper and...
  11. C

    back to back zener diodes does what?

    The maximum voltage appearing across them will be 6.8v + 0.7v = 7.5v in either direction
  12. C

    Wanted: As many small push button switches as possible!

    RS now have free next day delivery for a $2.00 order!! In Stock. Free next working day delivery Australia wide when ordered online That's a change from their $12.00 deliver charge a few years ago. As I say, "you can't beat the Chinese." They have simply joined them.
  13. C

    Wanted: As many small push button switches as possible!

    "Yeah, and I used to admire you. I'm just hoping you're not the real Colin Mitchel." No. I'm the FAKE Colin Mitchel - just using his name because he died years ago. I stole all his ideas and I'm now making lots of money. SHOW ME. How is 9 cents equal to 3 cents ????? How is post free equal...
  14. C

    Wanted: As many small push button switches as possible!

    "In sufficient quantity you can get tactile switches for similar prices from trusted suppliers." SHOW ME. "I can send you some excellent fake voltage regulators" No one is going to set up and make fake voltage regulators that work but are not reliable. The set-up to make a regulator is...
  15. C

    Wanted: As many small push button switches as possible!

    Simply look at Mouser price: Tactile Switches 6.0x3.5x4.3mm 160gf 100 pcs: $0.68 $68.00 !!!!!! SHIPPING CHARGE: $39.00 ORDER TOTAL: $107.00 China price: $3.11 and you say Mouser are not thieves !!!!!!
  16. C

    Wanted: As many small push button switches as possible!

    100pcs Tactile Pushbutton Key Switch Momentary Tact DIP 2 Pins 3*6*5mm $3.11 Free shipping How many do you want? You NEVER buy anything from Mouser etc. They are thieves.
  17. C

    6 Volt Motorcycle Alternator. Possible voltage regulator?

    It looks like the best way to prevent burning out the lamps is with a resistor, although you are bleeding nearly 50% of the generating capacity and the battery will take longer to charge and a 4 hour run at night will flatten the battery - if the specifications on the sheet are correct.
  18. C

    RC circuit

    "When pin 3 goes low again, the capacitor discharges through the resistor so there is no voltage across it." No. The capacitor discharges via the protection diode on Pin 5. "Like the charge-up of the capacitor, this discharge takes a certain amount of time;" No The capacitor takes almost...
  19. C

    pulse generators

    The operation of the circuit is much more complex than you think. I have never seen it presented before. Not only is it a blocking oscillator but it is jammed for 99% of the time to produce a 300Hz tone.
  20. C

    6 Volt Motorcycle Alternator. Possible voltage regulator?

    A 10 watt load is not going to take much from a 60 watt generator.
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