Type: Posts; User: schmitt trigger

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  1. Closed: Re: In accuracy in AC Voltage measurement

    The semiconductor companies sell double diodes which are specifically designed to protect microcontroller inputs from an overdrive.
    These have low leakage and low Vf.

    Having said that, if your...
  2. Closed: Re: Iran Core Transformator No Load Current (Core material)

    You need to measure real core loss, with a wattmeter that measures true power= V*I*cos(alpha).

    The core material with the lowest losses, all other things kept identical, is the best.

    When I...
  3. Closed: Re: Opamp buffer with 400nF output capacitance going unstable?

    Regardless of what compensation scheme you choose, hopefully you have (or can borrow) a "Bode Box" to check the phase/gain margin.
  4. Closed: Re: Regarding UC3844 IC used for PWM switching

    It appears that the schematic either:
    - has a drawing error
    - they are operating the 3844, which is a current mode controller, in voltage mode.

    Incorrect in either case.

    EDIT: Indeed, you...
  5. Closed: Re: High Input Current DC-DC Converter?

    The only way to properly decide, is to delve into app notes and data sheets from major semiconductor manufacturers.
    Lots of reading, my friend.

    When you find something similar to what you are...
  6. [SOLVED]Closed: Re: ACS712-5A AC Current Reading - How to?

    Something that you have not mentioned is the load type.

    All practical loads will have some sort of inrush current behavior.

    Some may last a couple of cycles, like the capacitor charging in...
  7. Replies

    Closed: Re: Functionl Generator 600 MHz

    Function generator, like a sine, wave, triangle wave generator?

    At 600 Mhz, you either have pure sine waves or a trapezoidal waveform.

    Because of the large amount of harmonics present in a...
  8. Closed: Re: Switch +/- 15v supply for audio preamp

    50 mA across 100 ohms would yield a voltage drop of 5 volts. Worse, the power dissipation, with all the channels enabled, would be 2 watts. I haven't seen the device ratings, but unless it is an IC...
  9. Closed: Four band audio bargraph display, using IN-13 Nixie linear bars.

    A couple of years ago, I stumbled upon an IN-9 Nixie linear display datasheet in Russian.

    Some fellow members (Prairedog and Altaero) in this forum, helped me translate it and my curiosity was...
  10. Closed: Re: Transformer Phase shift used in isolated zero crossing detectors

    Indeed, for applications which are not critical, this slight error could be calibrated via software to a much smaller error.

    I made another experiment, although I did not take waveforms:
    This is...
  11. Closed: Transformer Phase shift used in isolated zero crossing detectors

    In this and other forums, the question arises whether the same low power transformer used in the power supply, can be used to obtain an isolated sample for a zero crossing detector.

    I remember...
  12. Closed: Re: Motor dummy load resistor calculator

    What type of motor is the motor which is electrically loaded?

    Is it a BLDC or separately excited synchronous motor?

    If it is an induction motor, it will not self generate back EMF.
  13. Replies

    Closed: Re: reason for 50 Hz ac current

    The main reason for commercial power 50/60 Hz was chosen and not a lower frequency is twofold:

    -Lamp flicker and radio hum. Lower frequency ripple requires larger filter components.
  14. Replies

    Closed: Re: 2SC1971 Amplifier problem

    Can you attach those datasheet files?
    I'm not saying it is not possible, but I've never, ever seen a TO220 transistor whose tab wasn't the collector.
    The reason is very simple: heat transfer is...
  15. Replies

    Closed: Re: Is it a transistor or a mosfet?

    Hope that you have a DMM

    Start with the information on the following page:

    There are other web pages showing...
  16. Closed: Re: Ac induction motor constant speed control

    Induction motors are NOT brushed DC motors where you can measure the back-EMF to estimate the speed the motor is turning.

    You DO REQUIRE a tachometer. Can be optical, reluctance or magnetic. ...
  17. Closed: Re: Automatic light control circuit (On-Off)

    What c-mitra said above. With dusk and dawn conditions, or in cloudy days, without hysteresis the relay will be chattering.

    A LM393 comparator is both ubiquitous and ultra cheap. Use it to build a...
  18. Replies

    Closed: Re: forward voltage of LED diode

    Forward voltage drop depends on the LED wavelength.
    IR diodes indeed have forward voltages of around 1.7 volt, blue diodes are over 3 volts.

    But less than 1 volt?
  19. Closed: Re: shunt 24V rail to reference voltage using opamp?

    I fail to see how this circuit could work at all.
    Both the comparator and the optocoupler are open collector, and without a pull up resistor, the output will always be zero.
  20. Closed: Re: Phase current motor measurements with cro

    If, and that is a big if, I am understanding you correctly:

    You require three clamp type probes, a single differential high voltage probe, and a 4 channel scope.

    Connect the high voltage probe...
  21. Closed: Re: Getting trigger signal for 555 timer from elevator button.

    "I tried two circuits to get low signal to trigger 555 timer .
    I tried circuit 2 with 10k for R1 and R2 and i faced a problem . *the led of pc817 always on an this tell the controller the button...
  22. [SOLVED]Closed: Re: Generation of 4 Phase Shifted clock Signals

    Once upon a time, a complex timing waveform generation like the horizontal and vertical TV sync pulses, were designed using only vacuum tubes. But the sync generator was a refrigerator-sized...
  23. Closed: Re: ds1307 Rtc clock running slow by 6 second per day.

    In a previous company we had product which sold in +200k/year volumes and which used a DS1307. Produced it for over 5 years, perhaps over a million units total.

    Following the app note...
  24. Closed: Re: ds1307 Rtc clock running slow by 6 second per day.

    And all of those crystals that you have changed, are they different vendors and part numbers?
    Did you purchase them from reputable vendors or from e-bay?

    Having said this: If you really require...
  25. Replies

    [SOLVED]Closed: Re: Wiring of DC fans in Series

    The current draw of small DC fans do indeed change with rotation. Additionally, you cannot expect the two devices to draw the exact same current, even if they are the same brand and model.

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