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  1. duke37

    Troubles with elektronics project

    Yes, that is what capacitors do ! Xl = 1/(2*pi*f*C) What is the impedance when f = 0? What is the impedance with your frequency and capacitance? They pass AC and block DC.
  2. duke37

    Shotkky diode used with switching regulator Lm2576

    The regulator runs at 52kHz which is not exceptionaly fast so an ordinary fast diode should do. The Schottky will drop less voltage so the circuit will be more efficient. A 1N400x probably will not do.
  3. duke37

    Troubles with elektronics project

    The microcontroller may produce 4V peak to peak but does it produce this with an average of zero volts. That would be AC. If the signal is 0V to 4V then it is AC plus DC. What would be the effect of the following amplifier?
  4. duke37

    Frequency Detector

    The 8038, will generate a reasonable approximation to a sine wave and is tunable. If you do not want to vary the frequency of the tone, you could put a filter after the 555 or before the 567. The 567 is a phase locked loop with two detectors. One or the other should work on non sine waves.
  5. duke37

    low voltage corrector

    Contact the electricity supplier and get the supply put right. The voltage may be low now, if there is a fault, it may go high Do not try to bodge the mains.
  6. duke37

    Frequency Detector

    You will need to make a circuit to tune to the incoming frequency. In olden times, a circuit made with an inductor and capacitor was used. Nowadays an amplifier is used to eliminate the inductor. You will need to know the frequency to calculate the components. Once the tone has been detected...
  7. duke37

    Another Bat Detector

    C9 blocks any current through the emitter of Q3, I would take this out. D1 will limit the bottom end of the potentiometer to 0.6V. I see no reason for this. You are not making a hi-fi amp, just blasting out pulses. I would put a capacitor before the volume control so that when there is no...
  8. duke37

    Bridge Rectifier Output ??

    That circuit looks good but you have desribed it wrongly. The LEDs are not in parallel, it is the strings which are in parallel. As to the voltage to be used in the resistance calculation, use what you have. I would try the rectified voltage without smoothing as it is simpler, cheaper and...
  9. duke37

    Another Bat Detector

    That looks reasonable except that Q3 has no current flowing through it.
  10. duke37

    Level Shifting

    I thought that schottky digital circuits have a diode to stop the collector going well below the base and keep the transistor out of saturation to get faster switching.
  11. duke37

    LM324 op amp

    I should think that one op-amp will do the job. You need negative feedback NOT positive feedback. The circuit you show will lock either high or low.
  12. duke37

    1N4148 Diode circuit

    That looks better. Do you understand why?
  13. duke37

    Wafer Vibrations

    There was a requirement for a low frequency oscillator here a few days ago, it was suggested to use an 8038? chip. Alternatively, there is a voltage controlled oscillator in a LM567.You could also use a cmos 4047 oscillator/divider. Feed the ouput of the oscillator to an audio amplifier to...
  14. duke37

    1N4148 Diode circuit

    No, R1 needs to be connected to the potentiometer slider. Do you understand why?
  15. duke37

    Speed measurement

    You should look at the requirement for accuracy. You may need many pulses per revolution. When travelling fast, you can count the number of pulses in a certain time, you will need a lot of pulses. When travelling slow, you will need to measure the time between pulses.
  16. duke37

    need help with reducing DC voltage

    I think the only way of finding out the power available is with an oscilloscope or studying the circuit.. It could be DC, AC, full wave rectified AC or half wave rectified AC. Obviously, using a high voltage supply and using a resistor to drop to a low voltage involves a lot of lost energy...
  17. duke37

    substitute 4558 op amp for guitar compressor?

    Starting at the op-amp, this has a gain of 23. The output is rectified and smoothed to give a positive feedback voltage. The feed back voltage is fed to the second fet which is turned on when the gate is less negative. This shorts the signal to ground. So, the larger the signal, the more the...
  18. duke37

    Transistor Question

    Filedropper seem to want me to download a program. I am not doing that. Olivier's suggestion should be considered. Many years ago I made a Lindsley-Hood amplifier. This used 2N3442 transistors in the output. These are rated 140V. I do not think the transistor type is critical in this...
  19. duke37

    Transistor Question

    My word, that is complicated. The HT is 64V plus variation so I would go for the G version. Maybe a higher voltage transistor could be found. There is feedback so you should be able to get away without close matching. Before fitting the transistors, check the voltage at the emitter of Q6...
  20. duke37

    Transistor Question

    There are several ways of making a push-pull amplifier. I doubt if a 1960 amp would use a PNP transistor. To use two NPN transistors, they can be configured in series (totem pole) or drive a transformer. Matching is done by measuring the transistor characteristics. The transistors you have...
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