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Thread: Need help with Pulse DC

  1. #1 Need help with Pulse DC 
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    Here is what I have.
    A pulsed DC signal that when displayed on my voltmeter it reads more than 1200 V and 200 ma @RMS. I measured it with ACV and DCV and it still read 1200. It pulses at least 80 times a second; but for some reason It doesn't have enough power to turn on a little flashlight bulb or a simple AA motor (both DC).

    Any ideas on why it isn't powering anything?
    Could the volt meter be giving off false readings?
    Thanks,


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  3. #2  
    The Doctor Quantime's Avatar
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    I wish I could help. Maybe the meters are draining the power? Placing the meters after the bulb-would that work?


    "If you wish to make an apple pie from scratch, you must first invent the universe". - Carl Sagan
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  4. #3  
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    Yes, I believe it's quite possible your meter is giving a false reading. If the light doesn't light, and it is rated for that voltage, that would be proof positive. The cheaper meters I think just read the peak voltage and give you a "rms" voltage that is .707 of the peak a-c. There is such a thing as a meter that reads "true rms."
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  5. #4  
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    It gave me a peak of over 1600v and 350ma so I thought I would round down. My meter is a cheap-o and it reads a AA battery as it should be and it reads the 110v coming from the wall. I will try a analog one, thanks.

    Another question for you how do I create an frequency of over 1mhz (1,000,000 cycles per second)? I think that a welder operates around 1.2mhz but I am not sure.
    Any advise?
    Thanks,
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  6. #5  
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    Try this site for a design of a radio frequency oscillator.

    http://my.integritynet.com.au/purdic/oscillators.htm
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  7. #6 Need a little more help, Still a little lost 
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    I need to create a electrical frequency between 1.5mhz and 2.6mhz. I would like it to operate with less than .01a and 250v. I understand how a LC circuit works and know how to read a basic schematic but am no sure about the simple things. I assume I need a circuit board, but what size inductor and capacitor do I need, what do i use to connect it to my solenoid, what would I use for the input? I want to keep things simple. I am not trying to be lazy but am just a little lost when it comes to the specifics.

    Thanks for all the help,
    Abudantia
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  8. #7 Post subject: Need help with Pulse DC 
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    Hi abudantia

    First of its possible to have 1200V rms and 200 mA rms with 0 watts of real power. If your voltge and current spike occur out of sync then you will have no real power, it could almost be said that you have a very power power factor since all your power is imaginary.

    Now im not sure i understand you right, you want to generate a signal, osscilating between 1.5 and 2.6 MHZ. As far as i know you cant generate a signal with a LC circuit, these circuits can be used as filters becouse they have a natural frequency at which they like to osscilate and reject the rest. However they cant create their own signals.

    To create a signal you need something like a Wien bridge.
    http://www.interq.or.jp/japan/se-inoue/e_ckt18_2.htm

    But you dont want to make a sine wave right ? you want a series of pulses. Maybe you can attach a comparator to the output of the wien bridge to switch between two voltages values at a predefined value(i.e switch voltage between 5V and 0V when sine wave greater than 2.5V or so), not sure im gonna have to think about it a while.
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