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  1. audioguru2

    Some angel out there!! need help for motor speed control by pll

    It looks like you can use any of the signals from the encoder as your VCO signal. Attach your schematic of the LM565, encoder and amplifier for us to see what is wrong with it. I am in Canada.
  2. audioguru2

    Some angel out there!! need help for motor speed control by pll

    Sorry, we don't do somebody's homework. But here is a hint: go to Google and get the datasheet and the application note for the LM565. They show how to use its phase detector to control its VCO, then just use your tachometer as its VCO. Buffer its DC control voltage to drive your motor driver...
  3. audioguru2

    Infrared Receiver

    Your question #3 was correct.
  4. audioguru2

    Infrared Receiver

    Correct. Correct. No. The signal from the photodiode is loaded with 4 ohms (the reactance of the 1uF capacitor) in series with R2, and they are in parallel with R1 so the total load is about 100k ohms. Yes, half the signal is wasted. The value of the capacitor is way too high. It will take a...
  5. audioguru2

    50Hz when you touch Oscilloscope probe

    Hi Prateek, If your home or lab has electrical outlets on each wall and electrical lights on the ceiling then you are surrounded by high voltage AC at the mains frequency. Your body or a piece of unshielded wire will pick it up. It doesn't matter if there is a fan and the frequency doesn't matter.
  6. audioguru2

    A simple transistor switch for an LED light.

    Hi Gogo, Rason is incorrect. He says to use a base current of only the load current divided by the minimum hFE of the transistor. But a transistor's datasheet shows then the transistor isn't saturated, its collector voltage is from 1V to 4V. Datasheets show how well a transistor saturates when...
  7. audioguru2

    Convert 0-30V 3A PSU to 5A or more

    I don't think ordinary alkaline battery cells can be re-charged. I tried it and the "charge" lasts only a couple of hours if it is used or not. You can only discharge a cell a small amount then you charge its capacitance.
  8. audioguru2

    Convert 0-30V 3A PSU to 5A or more

    This project would need a complete re-design to get its output voltage up to 50V. It still has nearly the same schematic as the original. The output transistor has an added emitter resistor then two more output transistors and emitter resistors are added in parallel on the heatsink. Many parts...
  9. audioguru2

    FM deviation meter

    Hi AN920, I think the "additional electronics" takes the audio signal before de-emphasis and peak detects it with a peak detector like in the datasheet for the LM3915. You can add your two stereo channels and it probably doesn't need to be before the de-emphasis because high audio frequencies...
  10. audioguru2

    Electronic Stethoscope

    I think the project should work fine when the batteries measure a minimum of 6V while they are powering it. What load resistance do you have at the headphones jack? If it is 8 ohms or less then the positive battery has a high current drain when the sound is loud, possibly dropping its voltage...
  11. audioguru2

    220vac 50hz Inverter by Ferite core

    A laminated steel core is used at 50Hz. Ferrite is used at high frequencies. Make a 12Vp-p high current Pulse-Wiidth-Modulated square-wave or sine-wave using a high frequency clock and stepup the voltage with a ferrite transformer. Then filter the output and it will be 50Hz. Sorry, I don't...
  12. audioguru2

    Why doesn't my inductor give more kick.

    Hi H_man, It's great to hear that you got some nice big kicks with the new Mosfet. ;D The only difference I can see between the old and new Mosfets is that the new one has far less capacitance.
  13. audioguru2

    need help for cfl lighting

    Every transformer is different. The number of turns for a feedback winding is a ratio with the existing number of turns in the low voltage winding. You don't know how many turns are in the existng winding. There are lots of ways to make an oscillator without using an extra transformer winding.
  14. audioguru2

    project help with toy IC boards

    Hi GoGo, People and manufacturers call the supply pins of ICs many things. You should always look at the datasheet of an IC before connecting it to make sure. Motorola (now ON Semi) call the positive supply pin "VCC" and the negative supply pin "Gnd".
  15. audioguru2

    A simple transistor switch for an LED light.

    He explained about the components in the circuit. Useful? It doesn't blink with an oscillator, it is just on or off. The switch can turn on the LED and its current-limiting resistor without the transistor then it would be a dim flashlight.
  16. audioguru2

    FM Micromitter only transmitting 8M

    This circuit is a very good stereo transmitter. You don't need stereo for a bug. Make an ordinary simple FM transmitter for a bug.
  17. audioguru2

    Question about 74LS07

    The datasheet and description of it says, "open collector outputs". Its outputs are transistors to ground. A load or a resistor between the output and a positive voltage is supposed to pull the output voltage high.
  18. audioguru2

    project help with toy IC boards

    Hi Calahan, With only 3V for its supply, an amplifier can't amplify much without producing severe clipping distortion. The MC34119 will produce only a little more volume than the original toy. If the supply voltage for the amplifier is doubled to 6V then the power to the speaker is quadrupled...
  19. audioguru2

    project help with toy IC boards

    Sorry to hear that it didn't work. :'( Post the schematic of the MC34119 amplifier and we'll help you fix it.
  20. audioguru2

    need help for cfl lighting

    It is a feedback winding. Your schematic shows it shorted, and a resistor is missing for one of the transistors.
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