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  1. Replies
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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...
  5. 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...
  6. 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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    Closed: Re: Simple 50R I/O RF attenuator (1-30MHz)

    Just a thought - it is possible to use pre-set potentiometers with plastic center 'screws', either a slot or hex hole? You won't get perfect matching but you might get something close enough if you...
  8. Closed: Re: Rectifier diodes with bypass capīs & gounding speaker basketīs

    Based on what we have already said, Carbon dioxide resistors would be best but you might have trouble soldering to them. :)

    Really, the snubber circuits are not going to make one iota of...
  9. Closed: Re: ACS710 - pin 1 to 8 is shorted all together

    They are internally connected together through a copper loop so they should measure as shorted.
    The load current (or a proportion of it) passes through those pins and the internal circuits measure...
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    Closed: Re: Inrush current limiter

    A cheaper alternative might be a low-Q inductance in series with the incoming power. Something like a 50 - 100uH choke with a ~22 Ohm resistor across it. The inductor will slow the current rise and...
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    Closed: Re: specific use of volatile keyword

    Volatile would be a hint to the compiler to re-read the variable because it could have been changed by the ISR. For example, if your main code was counting 'x' upwards and your ISR changed the value...
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    Closed: Re: Inrush current limiter

    Most components are rated to handle higher current for brief periods so I doubt any damage would occur in any case.
    There are methods to limit the charge current to a capacitor but if the load is...
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    Closed: Re: Inrush current limiter

    ... and your thermistor tries to drop 2.5 * 10 = 25V as well.

    First explain what you mean by "it produces sparks" as this is nothing to do with inrush current.

    Brian.
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    Closed: Re: Building Blocks on an FM Band Receiver

    As per FvM, don't confuse FM and AM bandwidth requirements. The deviation of standard FM broadcasts is far wider than the bandwidth of normal 455KHz filters so you would 'chop off' most of the band...
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    Closed: Re: Building Blocks on an FM Band Receiver

    Before going further - when you say "FM Band" you seem to be referring to the domestic VHF broadcast band (~87MHz to 108MHz) where relatively wide band transmissions are used but the block diagram is...
  16. Closed: Re: Converting AF oscillator to use discrete components

    I'm not sure Brad's schematic is a true Wien-Bridge design as it uses different RC values in the series and shunt arms of the feedback loop and it also has additional phase shifting between the...
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    Closed: Re: Implementation of sine cosine using LUT

    You are quite right to correct me FvM - put my mistakes down to old age.

    They say your memory goes first ...... and I can't remember what comes second.

    Brian.
  18. Closed: Re: Rectifier diodes with bypass capīs & gounding speaker basketīs

    Perhaps they need one of these: https://www.ttvjaudio.com/The-Ultimate-Electrostatic-Headphone-Set-up-p/hif1230008.htm
    Thankfully it has free postage or it would be too expensive for me.

    On...
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    Closed: Re: tda7052a audio amplifier

    First thing to check is whether you really have a controllable volume at all. There are three type of TDA7052, the original with no letter at the end does not have electronic volume control at all....
  20. Closed: Re: Rectifier diodes with bypass capīs & gounding speaker basketīs

    I do not doubt any of the technical explanations about diode recovery time and how to snub the spike but I do have reservations about how relevant it is in this situation. We are talking about a...
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    Closed: Re: Implementation of sine cosine using LUT

    Symmetry - 32 points in 45 degrees means (360/45)*32 = 256 points in total. An average of a little over 1 degree per point but also a convenient LUT size for software/hardware to use.

    Brian
  22. Closed: Re: Regulating temperature of mains connected heating element: Skipping mains half cy

    Not necessarily, it may work the same way as some 'thermostatic mixer taps' with a constant heat source but motorized mixer valve.

    Brian.
  23. Closed: Re: PIC1F1508 with four PWM outputs operating at different frequency?

    Provided your PWM frequency isn't too high you can generate your own PWM waveform in software like this:

    1. use one of the hardware timers to generate the lowest base PWM frequency.
    2. Use...
  24. Closed: Re: PIC1F1508 with four PWM outputs operating at different frequency?

    See data sheet section 23.1.1


    Brian
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    Closed: Re: tda7052a audio amplifier

    ... also note that the wiring to pin 4 is wrong!

    Brian.
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