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Type: Posts; User: betwixt

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    Closed: Re: Random Time Delay in C

    Wouldn't this do the same thing:
    delay(((rand() % 6) * 1000);

    Brian.
  2. [SOLVED]Closed: Re: PIC24FJ256GB210 Controlling Output Voltage

    The resistor and LED seem OK but what is the supply voltage (VDD) to the PIC. It needs to be a little higher than the LED needs to allow for some drop in the internal circuits. The maximum...
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    Closed: Re: What does 1

    Are you sure?
    1 << (twint) shifts a '1' left by '(twint)' times, it creates a value but does it change the contents of a register?

    Brian.
  4. Closed: Re: Measuring voltage drop across a diode in a switching circuit

    So if you did this: (forgive the crude graphics)
    +8V ------ Diode ------- (no connection)
    0V ----------------------------------------
    And you place a meter across the diode you would expect to see...
  5. Closed: Re: Measuring voltage drop across a diode in a switching circuit

    Only when the diode is conducting and passing enough current. If the voltage can't drop below 7.7V after the diodes it probably means there is already that much from storage in the capacitors or...
  6. Closed: Re: Variable Resistor clamping and output behaviour for LM2596-ADJ

    I've never seen a regulator that takes it's feedback from the input voltage!
    I suspect R36 should go to ground instead of the input.

    To get the voltages you need, find the values for the lowest...
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    Closed: Re: Will a filter block this waveform?

    I think the bottom line is this:

    If you want a clean 40MHz signal it is best to generate one as near a sine wave as possible then use minimal filtering to eliminate harmonics. If you want to start...
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    Closed: Re: HUM in transmitter PSU

    That suggests you are becoming part of the signal path.
    Can you check that the PSU you are using really has a ground connection. There should be one but I'm thinking if you are using a laptop supply...
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    Closed: Re: HUM in transmitter PSU

    Only that there is no frequency modulation on the carrier. When receiving in CW mode you probably wouldn't hear very low frequencies because of the receiver audio filtering.

    What happens if you...
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    Closed: Re: pull pull down meaningon GPIO

    You are not noticing the resistor symbols on the diagram.

    The pull-up and pull-down are not direct connections to VDD or VSS, they enable a weak current source to maintain the pin in a known state...
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    Closed: Re: Will a filter block this waveform?

    Not necessarily, but probably.
    If the module produced a pure sine wave output it would not have any harmonics. A sine wave is a single frequency. If the output is not a sine wave, even with the...
  12. Closed: Re: RFID Transponder transmission and reception working

    A bit over simplified but this will give you the general idea:

    In RFID systems, the transmitter sends pulses at the chosen frequency, it also monitors the amplitude of pulses it sends.
    The 'tag'...
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    Closed: Re: Will a filter block this waveform?

    Does not compute Will Robinson. (with apologies to 'Lost in space' fans). A crystal oscillator generally can't be used for FM transmission.

    I'm guessing you used a crystal oscillator module,...
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    Closed: Re: question regarding this C operations

    It is a pointer, usually to a structure member.

    Brian.
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    Closed: Re: Algorithm Implementation

    You sent us three fragments of mystery code with only one comment between them.

    We don't stand a chance of working out what is wrong if we don't even know what the variables are for.

    Brian.
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    Closed: Re: question regarding this C operations

    Standard C language.

    The '|' means logic OR.
    The '=' means 'becomes' in this context.

    '|=' means the left value becomes itself OR'ed with the right value.

    Without knowing what processor...
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    Closed: Re: HUM in transmitter PSU

    Sounds like a ground hum loop to me then. There is a difference in voltage between your audio input ground and the LM317 ground. You should have a capacitor (at least 10uF) from the input pin of...
  18. Closed: Re: Dont need a super accurate, super high bandwidth In Amp...

    Can't you just scale the two voltages and feed them differentially to the two amps inputs, one with low gain (or unity) to give the difference and the other with high gain so it works like a...
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    Closed: Re: DSB power generation

    My thoughts exactly FvM. That and because the same device running as a high power oscillator has to work in linear mode as well.

    Even the idea of balancing two 30A SMPS rectifiers at 7MHz is...
  20. Closed: Re: Problem with current loss with increasing length of wire

    The only option is to use thicker wires I'm afraid. The voltage drop is caused by the resistance of the wire (Voltage drop = Current * Wire Resistance). As the voltage and current are fixed, you...
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    Closed: Re: DSB power generation

    You are getting the idea!

    The best you could achieve with the present circuit is a 50% reduction in power usage because as you now realize, the oscillator must always run. Even at half power with...
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    Closed: Re: DSB power generation

    Don't let me stop you trying them but I think you will be disappointed. They are SMPS rectifiers, intended for pulsed high current at relatively low frequencies (< 200KHz) so running them at >35...
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    Closed: Re: Help identifying some parts

    Looks to have a capacitor across two pins and another capacitor across the other two pins. I would guess this is a small SMPS board and the part is a filter choke.

    If I'm right, you should measure...
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    Closed: Re: TMR 6-0523 does not start

    The TMR6-0523 can only deliver 200mA. You do not say what your 'lot of audio amplifiers' consist of, do they draw any additional start-up current to charge capacitors?

    Brian.

    - - - Updated - -...
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    Closed: Re: DSB power generation

    The minimum turn on and turn off times of the diodes added together must be less than 1 cycle at 7MHz (142nS) for it to work at all and it should preferably be much less than that.

    It is difficult...
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