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Type: Posts; User: betwixt

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  1. Closed: Re: Offline isolated Two transsitor forward with synchronoys rectifier control circui

    I agree that for very short delays you can utilize the propagation delay of logic gates but the issue of exact thresholds and the time it takes to pass them would apply anyway, regardless of whether...
  2. Closed: Re: Offline isolated Two transsitor forward with synchronoys rectifier control circui

    64MHz is no problem. Don't think of it as needing 'VHF' circuit design because externally most use a slower and cheaper XTAL oscillator and an internal PLL frequency multiplier. For example 16MHz...
  3. Closed: Re: Offline isolated Two transsitor forward with synchronoys rectifier control circui

    If you are going to use a microcontroller there is no reason to use more than one. Any MCU running at a reasonable clock speed can produce all the switching signals and handle the regulation as well....
  4. Closed: Re: Sensitive metal detector using microcontroller ADC channel.

    Not a 555, that would be a bad choice. A comparator would be best with a schmitt trigger logic gate next best. If the Arduino has a schmitt trigger on one of its port pins that would work too. I use...
  5. Closed: Re: Basic 12v Battery VOLTAGE METER, more resolution needed

    Its a long time since I used an LM3914 but I think it's possible to lift the bottom of the divider chain above ground to set the minimum reading. The LEDs then display linear steps from bottom to top...
  6. Closed: Re: White residue after solder mask develope!!!

    I think they mean the uneven surface after plating, you can just see it against the gold. I suspect this is the underlying copper being uneven and the gold plating just makes it more obvious....
  7. Closed: Re: Metal detector with Arduino ADC channel.

    That is the correct type of coil but the inductance depends upon how you use it. In its simplest form, you use the inductance and a small capacitance across it to tune an oscillator then measure its...
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    Closed: Re: Tracking Phase comparator Logic

    If I understand the requirement and it has to be done digitally, an XOR function of the two signals will produce a high during the time phase difference. What you need to do is count at 5uS rate...
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    Closed: Re: MOC3020/BTA41 circuit problem

    Hasan, please start a new thread with your questions as these are not the same as the ones Abuhafss is posting.

    If shorting LED1 makes it work it means I was right about not having enough current...
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    Closed: Re: MOC3020/BTA41 circuit problem

    I If the bridge rectifier is directly across the AC it has to bear the full AC voltage, if you place the resistor before the bridge it only has to handle a low voltage. The maximum voltage it can...
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    Closed: Re: MOC3020/BTA41 circuit problem

    Note the different resistor arrangement around the triac! The Chinese design uses a capacitor to filter noise from the gate and to partially snub spikes from across the line. For driving a heater...
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    Closed: Re: MOC3020/BTA41 circuit problem

    Two points:
    R4 value looks too low, it is only there to ensure the gate has some leakage current when the output of the MOC3020 is high impedance, I suggest a value of 2.2K or higher. Remember that...
  13. Closed: Re: Metal detector with Arduino ADC channel.

    It might work as a strong magnet detector but never as a sensitive metal detector!

    Metal detectors work by measuring the effect the metal has on a magnetic field, either by absorbing or de-tuning...
  14. Closed: Re: [PIC] Car Cooling System PSU Design Related

    Does your application permit charging one battery at a time?
    With some MCU intervention and some current steering it is possible to charge one at a time but you will not be able to use the '24v'...
  15. Closed: Re: [PIC] Car Cooling System PSU Design Related

    There is a clue in the MOSFET symbol about that!

    I can't understand why you need the 15V. If it is to charge the batteries you can't do it while they are in series, you need >24V to do that.
    If...
  16. Closed: Re: [PIC] Car Cooling System PSU Design Related

    Doesn't look at all right to me.
    I'm not sure what any of the circuit really does. D2 seems to have no purpose at all. If the DC-DC converter is to step down the PV voltage so it can charge the...
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    [SOLVED]Closed: Re: problem with coding 123

    I understand that Klaus but it doesn't increase 10 bits to 12 bits, it just multiplies the result by 4, the LSB will always be zero. The ADC is still 10 bits.
    Some Arduino device can use 12-bit...
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    [SOLVED]Closed: Re: problem with coding 123

    ... and what is the point in multiplying the result by 4? It is still a 10-bit value with zeroes at the end. It may be stored with extra bits but the precision isn't increased to 12-bits.

    Brian.
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    Closed: Re: MAR8 prior to AD8307

    Yes, but with the risk of damaging the meter and possibly the IC at higher signal levels. It isn't a safe strategy.
    A better approach if you want to follow that route is to amplify the lower voltage...
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    Closed: Re: MAR8 prior to AD8307

    If you add a capacitor at the output of the internal amplifier it may go unstable. Check the data sheet for the AD83xx device you choose, there is provision for a filter capacitor at one of the pins...
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    Closed: Re: MAR8 prior to AD8307

    It has a built in voltage amplifier so all you have to do is add a series potentiometer to limit the meter current. You would need a reference to adjust calibration accurately or apply a voltage...
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    Closed: Re: MAR8 prior to AD8307

    If you use a 100uA meter you can probably drive it directly from the AD83xx.

    Brian.
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    Closed: Re: How to create a voltage selector circuit

    I thnk a better topology is to feed your voltage to all the comparators in parallel but set a different threshold for each one. The will give you a 'bar graph' output with none, lowest, lowest and...
  24. Closed: Re: VU Meter only with 1LED (PWM) no IC except for OPAMP

    You can't use the outputs of comparators directly because all you get is an on/off indication of the instantaneous level. You would see the output flash at the frequency of the audio instead of its...
  25. Closed: Re: VU Meter only with 1LED (PWM) no IC except for OPAMP

    Not PWM, what you need is an op-amp as a gain stage, a rectifier (either diode or better still an op-amp based precision rectifier) to give you a DC level proportional to the sound level. Then you...
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