555 timer supply voltage/current

Discussion in 'The Projects Forum' started by jmyown, Jul 12, 2011.

  1. jmyown

    Thread Starter New Member

    May 29, 2011
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    I am building a 555 timer circuit as a PWM to output to a coil. I know I need diodes to manage back EMF from coil. My question is can I use a 12V/2A DC trickle battery charger to power my circuit?

    Is it possible (do I have to) to limit the current to the timer to keep it within operating spec's?

    Basic circuit objectives is approx 50% duty cycle at about 7Mhz.
    555 timer used is from Radio Shack.
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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    It depends on how you're using the coil. If it's for a transformer type arrangement, you'll want a snubber instead. If it's for a relay, then you could use a regular diode, or a Zener back-to-back with a regular diode to make the current stop more quickly.

    The output from a trickle charger is not normally filtered as in a typical power supply. If you had an oscilloscope measuring across the output, you might see variations up to 18v or so; some higher than that.

    Some trickle chargers won't output anything at all if the output has less than a certain threshold voltage; this is to prevent the charger from becoming overloaded if someone tried to charge an absolutely dead battery, or the wrong voltage battery, etc.

    It's difficult to tell by your initial specifications. If it's a really old charger, it may simply put out rectified AC at low voltage (maybe up to 18v or 20v), and depend on the impedance of the transformer to limit the current.

    You're not going to get anywhere near 7MHz with a typical 555 timer.
    Some of them will go 2MHz.
    They carry more than 1 model of 555. One of them is a TLC555, a CMOS version. Another is a BJT version.
     
  3. jmyown

    Thread Starter New Member

    May 29, 2011
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    Details for my project:

    Timer: 555CN (Radio Shack #276-1723)

    Coils to be driven by timer circuit: Hand wound Starship type windings with magnet wire from Radio Shack. Coil to be used as transformer type arrangement which is to be sandwiched between two ring magnets from speakers.

    Diodes for managing back EMF from coils:1N4148 & 1N4001

    I could further use a rectifier bridge to manage voltage supplied by intended battery charger supply to timer circuit.

    Project objectives: Observe and measure any current produced by MEG (Motionless Energy Generator) configuration. Use a flat coil sandwiched between two ring magnets from speakers. Coil is driven with timer circuit to stimulate magnetic fluxes in ring magnets. Use a coil around outside of ring magnets to pick up magnetic fluxes and generate measurable current.

    This is a purely experimental configuration of components and does not follow any current MEG designs. However it may follow basic principles of MEG operation.
     
  4. SgtWookie

    Expert

    Jul 17, 2007
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    You should read this:
    http://en.wikipedia.org/wiki/Motionless_electromagnetic_generator
    I'm not certain whether Bearden & company are simply misguided or an outright fraud; but with claims of needing $11 million dollars to develop it into a viable commercial form has me leaning heavily towards the latter assertion.

    You also need to read this thread: No more HHO, overunity, or Meyer
    The "Starship" and MEG claims are simply preposterous. You simply cannot get more energy out of something than you put into it, no matter how fervently you might wish that to be the case.
     
  5. jmyown

    Thread Starter New Member

    May 29, 2011
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    Thank you SgtWookie for your replies and technical advice. Although the MEG devices have been generally discredited I still would like to test my theories out. If you have any additional information/advice in reference to my project and post threads, it would help. :)
     
  6. SgtWookie

    Expert

    Jul 17, 2007
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    It won't produce power; only consume it. I can give you an iron-clad guarantee on that.

    Now if you have a project that involves practical circuitry that will be based on scientific fact rather than fiction, feel free to start a new thread.

    However, this one has run its' course. The board simply does not entertain discussions on such flights of fancy.
     
  7. jmyown

    Thread Starter New Member

    May 29, 2011
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    SgtWookie, I clearly understand your position about this controversial subject. However my original question regarding 555 timer circuits still stands. I am NOT ASKING for HELP in reference to solving the mysteries of Over-unity devices. I thought this forum could help me learn and understand some basic circuit principles. If 555 timer circuits fall beyond the forums discussions or help I will seek other avenues. What I do with my 555 timer circuit is my business (since you are closed to any other phenomena beyond your logical understanding).
     
  8. SgtWookie

    Expert

    Jul 17, 2007
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    Here is National Semiconductor's page for the LM555 timer:
    http://www.national.com/mpf/LM/LM555.html#Overview
    Here is the datasheet for the LM555: http://www.national.com/ds/LM/LM555.pdf
    Note the chart on the bottom left of page 8 indicating free running frequencies in the astable multivibrator mode, and that the chart ends at 100kHz.
    You previously stated that you wanted a 50% duty cycle at a frequency of 7MHz.
    As you can see by the chart, 7MHz is not within the capabilities of the LM555 timer.

    So, I can't help you with your request.
     
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