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  1. WHONOES

    How to run BLDC motor from an old printer

    Best guess is that it is a 2 phase stepper motor. These are fairly straightforward to drive with a bit of associated electronics.
  2. WHONOES

    Design bass amplifier

    I tend to make my own inductors then I know they will be accurate. How on earth did you measure a manufacturers demo speaker? presumably it would have been in a shop or on their premises.
  3. WHONOES

    Beginning electronics, understanding whats actually happening

    Sorry. but I don't think you understand the concept of learning. Look up the metaphor "Dwarves standing on the shoulders of giants".
  4. WHONOES

    Switch for 110V 16amp AC

    Using a relay driven by the switch would be simple.
  5. WHONOES

    MOSFET Circuit Help

    Look up Bernoulli's theorem. It basically states (simplifying it) that air or any fluid for that matter is at a lower pressure than the surrounding air. The fan moves air hence pressure drop. You may be stuck with what you see to a degree unless you find a solution that doesn't involve a fan...
  6. WHONOES

    Design bass amplifier

    I suspect Josejos is wanting to build an active speaker. As for a passive speaker crossover, it is possible to construct one that sum's to zero at the crossover frequency using the Linkwitz - Riley type. The only issue is that there is a 180degree phase difference between the 2 halves. This...
  7. WHONOES

    Active load on a differential BJT Amplifier

    If you are getting 30dB gain with a common emitter circuit why don't you just use a second stage to give you the other 10dB that you need?
  8. WHONOES

    Active load on a differential BJT Amplifier

    What sort of bandwidth are you after. I see that the device you have chosen is a μwave device.
  9. WHONOES

    Active load on a differential BJT Amplifier

    Simple explanation. Because the current flowing into the collector of one transistor in a current mirror pair will be reflected in the second transistor. With the pair connected as in your circuit, the collector current in either transistor is to all intents infinite therefore, both transistors...
  10. WHONOES

    Active load on a differential BJT Amplifier

    Because with the NPN arrangement for the current mirror as shown on your 2nd sketch, the top 2 transistors will be turned hard on resulting in the collectors of the lower 2 transistors being pulled up to a few millivolts below the 5V supply. Also, the current source at the bottom doesn't look...
  11. WHONOES

    Active load on a differential BJT Amplifier

    Also, the chosen current through your transistors is much to high at 30mA each. At that value, the 300Ω resistors will have 9V across them, much more than the 5V supply which of course is impossible. A more suitable value would be 1 - 2mA in each transistor. Harald is correct, the current mirror...
  12. WHONOES

    555 pwm controller.

    I've got rellies in Oz. Like your attitude.
  13. WHONOES

    555 pwm controller.

    I think that HellasTechn claimed that he had tried to find a replacement but could not. You must be an Aussie with that turn of phrase!
  14. WHONOES

    Clarification of terms S:N

    Spot on AG.
  15. WHONOES

    DIY Electric Shocking Mouse/Rat Trap

    Get a Jack Russell dog. They were bred for just that purpose.
  16. WHONOES

    555 pwm controller.

    Up to a point. But you must bear in mind that the FET gate pulse current will have a fairly high amplitude which would necessitate a fairly low impedance volt reg circuit. For my circuit, I would recommend, for a 24V supply, a 100Ω resistor and 3 to 5W 12V zener and at least a 220μf cap.
  17. WHONOES

    555 pwm controller.

    Try the attached circuit for a very simple 555 PWM motor driver using an N channel MOSFET. In the circuit diagram, the motor is represented by R1. It should have diode across the motor with the cathode connected to the + supply.
  18. WHONOES

    How to make this circuit unity gain?

    Just came up with a discreet headphone amplifier. For reasons of stability (which I won't go into) It has a gain of about 4. If that is too much then pot down the input voltage. See attachment. It has a lot of notes on it that you should read. It will output a little over 5W rms into 8Ω so may...
  19. WHONOES

    What are these 2 "extra" red wires for? Li-Ion RC Battery

    Like your sense of humour.
  20. WHONOES

    Trying to convert a M2 silent pro PSU into a bench top power supply

    What sort of voltage and current are you wanting?
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