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558 timer for triple timing use...

Discussion in 'General Electronics Chat' started by hackware, Jul 30, 2017.

  1. crutschow

    crutschow Well-Known Member Most Helpful Member

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    Can you post a link to that Mississippi Ag Dept. discussion on this?
     
  2. hackware

    hackware New Member

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    All the discussions were phone calls, over the years...

    I spent 30+ years in silicon valley, came back to mississippi few years ago (graduated high school in 1976 from a class of 12)...

    william...
     
  3. alec_t

    alec_t Well-Known Member Most Helpful Member

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    For a given HT voltage, the shorter the distance between the ground electrode and the other electrode(s) the stronger will be the electric field. If the pond is deep, the ground electrode is at the boat and the other electrode(s) is/are at the pond bottom then the field will be weak. A stronger field would exist if all electrodes were at the pond bottom.
     
  4. dave

    Dave New Member

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  5. shortbus=

    shortbus= Well-Known Member

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    I'll probably get shot down on this idea, but here goes. Wouldn't a microwave oven transformer, powered with a portable generator in the boat work? Aren't the secondaries pretty high voltage?
     
  6. hackware

    hackware New Member

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    Quote from google search:
    A typical home microwave transformer has two secondary windings. One winding provides 3.1 to 3.2 volts, while the high voltage winding provides between 1800 - 2800 volts (average ~2200 volts).

    Though the power might be more then any but a custom wound transformer...

    william...
     
  7. hackware

    hackware New Member

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    How would you suggest implementing this?

    I copied the set up used by the Mississippi Agriculture Department. Their set up uses 2 drag lines to compensate for pond bottom water differences. Most fish zapper documents only use one, but all of them use the boat (if metal) or a floating/submerged metal bar as the high voltage return path.

    william...
     
  8. crutschow

    crutschow Well-Known Member Most Helpful Member

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    I read an ad for a high power fish stunner that outputs a 2 Joule, 2,000V pulse.
    A standard ignition coil only outputs about a maximum of 100mJ of energy when used in the standard flyback mode.

    To get higher energies you could use a capacitive discharge system.
    If you charge a 1,600μF capacitor to 50V and discharge that through the primary of an ignition coil you would have a 5000V, 2 Joule pulse.
    So you would need a DC-DC converter to go from 12V to 50v to charge the cap and then an SCR to discharge the cap through the coil.
    The SCR can be triggered by a 555 astable.
    Possibly.
    But I would not power the transformer directly from an AC generator since the output would then be definitely lethal. :eek:

    Likely the best way would be to charge a 300μF cap to 120V and discharge it through the 120V primary of a microwave transformer.
    That would give a 2 Joule, 2,000V pulse, similar to the commercial stunner.

    To operate from 120Vac you could use an SSR (solid-state relay) that has zero-crossing circuitry to generate one cycle of the 60Hz through the primary.
    A 555 astable could trigger the SSR at the desired pulse rate.

    The pulsed outputs would certainly give you a jolt you will remember, but it's not likely to cause death. ;)
     
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  9. hackware

    hackware New Member

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    That fish zapper seems like the one the MS-Ag dept. uses, except they claimed it cost $1500 (rip?)...

    Not so interested in using an 120vac inverter in a metal boat, although a 12v car battery generating 1KV+ can still kill you...
    10 ma through the heart is all it takes...

    The 50v cap/scr to the coil idea is interesting...

    Perhaps a variable pulse width gate to a voltage accumulator circuit would give me the variable voltage I need.
    (ie: variable number of pulses charge up the cap)

    That fish zapper user guide states that their unit works better on bigger fish than smaller ones. Not what I have observed nor what the MS-Ag guys state...

    william...
     
  10. hackware

    hackware New Member

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    LONG POST WARNING...

    From the following site "
    http://electrofishing.net/guide/", found the following...

    CRITERIA FOR CHOOSING AN ELECTROFISHING UNIT


    ELECTRICAL PARAMETERS

    Most of these specifications are for control boxes (pulsators).

    Here’s various equipment attributes that can give you the capability to improve capture efficiency and precision.

    Power, maximum output average: backpacks typically are 200 Watts or 400 Watts average; control boxes for boat units range from 1,700 Watts to 9,000 Watts average and more. Higher power capacity can increase the upper range of water conductivities that you can effectively electrofish.

    Waveform type: may have one of more of these types- alternating current (AC), direct current (DC), or pulsed direct current (PDC). Having all three options in a control box provides more capabilities for capture and fish trauma control; AC often extends operating range into lower or higher conductivity waters. DC can be very effective for attraction of fish to the anodes and often is less injurious to salmonids. PDC can be very effective while putting less power demand on your equipment. Some units have a special form of PDC, the gated burst or complex pulse system, primarily used to minimize fish injury potential.

    Voltage control: Continuous or small increments (e.g., 5 Vpeak per selection) are desirable. Large increments (>= 50 V) can make it difficult or impossible to apply required outputs for standardization or reduction of fish trauma. A large voltage increment can result in the lower setting resulting in poor catch and the higher setting resulting in shutdown due to excessive power or current draw. Common maximums range from 600 Vpeak to 1000 Vpeak direct pulsed current, and up to 700 Vrms (AC); higher voltage can extend effective fishing range into lower water conductivities.

    Amperage: maximum peak current typically ranges from 10 amps to over 75 amps in the higher power units, with the maximum near 600 peak amps in one U.S.-built control box; higher amperage capacity can extend effective fishing range into higher conductivity waters.

    Frequency: Typically ranges between 7.5 – 120 pulses per second for PDC (50 or 60 Hz typical for AC). However, higher frequencies, as 300 pps, are showing promise for capture. Some units have capacity up to 1000 pps. The best option is continuously adjustable or fine control by 1 pps increments. Often higher frequencies, at least up to 120 pps, result in lower response thresholds and are more effective (i.e., less power needs to be applied for a particular capture-prone response). Concerning fish trauma, the ability to control frequency enables waveform management to lower fish injury potential.

    Pulse width: Units range between less than a millisecond to 10 milliseconds or more; Typical applications use 1 millisecond or more (often up to 4 – 6 milliseconds); pulse width and frequency affect duty cycle.

    Duty cycle: Best control is continuous (1% increments) from 1% – 100% (DC); Research has suggested that the optimum range of duty cycle for capturing fish ranges between 20 – 40% so a 40% maximum is sufficient in many cases, although higher duty cycles can increase attraction (taxis). Good control of duty cycle gives you the flexibility to adjust waveforms to improve fish reaction, particularly attraction.

    Waveform shape: Shape can vary across models (e.g., capacitor-discharge exponential decay, square, rectified AC) for all three major waveform types. There has been limited research on comparison of capture efficiencies and potential for fish injury among different PDC waveform shapes. Square waves compared favorably in capture efficiency and lower fish injury and stress levels. “Rounded” PDC pulses from rectified AC appear to require higher power than square waves to sample at the same efficiency. The square shape also facilitates accurate metering and description (e.g., duty cycle). Note that square waves can have slanted tops or spikes when under heavy loading, as in high conductivity waters. An operational capacity analysis with a scopemeter can indicate how well a unit keeps the waveform shape intact under various levels of loading.

    Metering: It is critical to have good peak reading meters; the best configuration is a peak reading output voltage meter and a peak output amperage meter; however, either a peak volt or a peak amp meter will allow you to standardize by voltage or amperage (of course, really power). If you have an average reading amperage meter, you’ll need a good duty cycle meter or a recently calibrated duty cycle control to convert average to peak. Due to wave non-symmetry, using RMS voltage or current meters for AC is not recommended. You’ll need a peak-reading voltage or current meter for AC as well. Without metering, assuming that the dialed-in values (setting) for voltage is equal to output may be problematic, particularly at high loadings (usually high conductivities); if you don’t have metering, the best option is to incorporate testing equipment (e.g., a scopemeter-current clamp combination to serve as the amp meter). Do not trust the setting value.

    Electrodes: The design of electrodes is under your control and preferences. For DC or PDC and often AC electrofishing, typically you want the cathode to have larger surface area than the anode. High resistance can limit power output.

    Operational Capacity: Here you are trying to answer the question: “What is the range of water conductivities that can be successfully electrofished with the unit under consideration?” (Do not rely on conductivity ranges given by manufacturers). First determine 1) the range of water conductivities that you will encounter and 2) the level of power required for successful electrofishing across water conductivities with a particular gear (use Excel files EF Goal Power or Electrofishing with Power or the Electrofishing Tool app). Note: a determination of successful electrofishing means that at a given water conductivity and using an effective waveform, you can generate more peak power than you need. Next, run an output analysis of your gear. You’ll need to input certain equipment specifications from the manufacturer and electrode resistance. Use the Excel files Boat Power and Backpack Power to estimate the effective electrofishing range across water conductivity.

    SAFETY FEATURES
    Safety features on equipment have been critical to providing safer working environments for crews. Equipment safety requirements is a topic that can be specific to the country or region, depending upon national codes. Features that are standard or desired include construction to electrical standards (wiring capacities, conductors in conduit, water-resistant plugs, etc.), an easily-accessible safety (on-off) switch (e.g., mushroom switch), a “power on” light, safety switch on hand-held electrode handle (backpacks), foot-activated switch on boats (pedal, mat, or kick-plate), tilt-switches on backpacks (forward, backward, and/or sideways), and railings on boat work decks. Additional features to consider include a backpack immersion switch (when operator goes down vertically into the water), anode out-of-water switch, battery compartment splash guard, and enunciator (“power on” sound for battery-powered models). Don’t forget the all-important personal protective gear as insulative gloves.

    summary of (my) requirements next post...

    william...
     
  11. hackware

    hackware New Member

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    Voltage control: Continuous or small increments (e.g., 5 Vpeak per selection) are desirable.
    (Common maximums range from 600 Vpeak to 1000 Vpeak direct pulsed current)
    (I seem to have been very wrong in some of my assumptions here...)(bigger is NOT always better...)


    Amperage: maximum peak current typically ranges from 10 amps to over 75 amps in the higher power units...
    (higher amperage capacity can extend effective fishing range into higher conductivity waters.)


    Frequency: Typically ranges between 7.5 – 120 pulses per second for PDC...
    (50 or 60 Hz typical for AC). However, (higher frequencies, as 300 pps, are showing promise for capture)
    (best option is continuously adjustable or fine control by 1 pps increments.)


    Pulse width: Units range between less than a millisecond to 10 milliseconds or more...
    (pulse width and frequency affect duty cycle)


    Duty cycle: Best control is continuous (1% increments) from 1% – 100%...
    (Research has suggested that the optimum range of duty cycle for capturing fish ranges between 20 – 40% )
    (Good control of duty cycle gives you the flexibility to adjust waveforms to improve fish reaction, particularly attraction.)


    As I seem to have drifted from original focus of this thread, I'll return to it and state the needed circuit outputs...

    (signal-pulse) refers to 558/555(s) circuit outputs

    1) variable frequency oscillator (signal-pulse frequency)
    2a) variable pulse width triggerable monstable (signal-pulse width)(single zap duration)(in milliseconds 1-200)
    2b) variable pulse width triggerable monstable (signal-pulse gate)(zap pulse stream duration in seconds 0.1-300)
    3) variable voltage generator (signal-pulse voltage)(50v cap/scr to the coil idea?)

    william...
     
  12. crutschow

    crutschow Well-Known Member Most Helpful Member

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    The capacitive discharge pulse design puts out a very short pulse.
    You cannot significantly vary its width.

    If you want a variable pulse width, then you would need to use a different design, such as driving a microwave transformer with pulses of AC.
     
  13. hackware

    hackware New Member

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    heh... just so happens we got an old microwave sitting in the barn...

    was hoping to avoid building/buying custom transformer...

    but will get to that after control signal circuits are complete...

    (will probably test with ignition coils anyway...)

    can always use my new ignition coils on electric fence...

    william...
     
  14. crutschow

    crutschow Well-Known Member Most Helpful Member

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    So if you want a varying pulse width, then it would seem driving the μwave transformer from a 120Vac inverter with short bursts of the AC on the primary may be the way to go.
    To vary the voltage you would have to vary the 120Vac from the inverter.
    (Got a variac transformer?)
     
  15. hackware

    hackware New Member

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    No... :-(

    But the transformer input would be 120vac MAX (variable voltage requirement), so a drive circuit is needed anyway...

    But on the good side, looks like my original assumptions of needing superKV were wrong anyway...

    Seems like most units used by the pros max out around 2-3KV...
    (Although found a couple $10K+ "real" units going to 6KV... They stated their use were for Louisiana swamps...)

    Most of the units for sale boasting HIGH KV units I think are built on the "bigger is better" rule of marketing...

    Anyway, I might get away with the microwave transformer with no mods at all, just a hairy set of signal/driver circuits...

    If it ends up needing more power than the microwave transformer can supply, there's an old welding unit I can get my hands on...

    Would most likely have to rewind it, cause I think welder units only output 300 volts or so... (but their transformers are massive)

    Last guy I talked with at the Ag-dept, said "even the season and weather can change the required settings to get the big ones hiding on the bottom
    of ponds in Mississippi"...

    Also found out why I can't get anybody at the Ag-Dept to come out... They only have time for "commercial pond farmers"...
    (25 years or so ago, when my father had the pond stocked from MS-Ag-Dept, they bent over backwards to help in every way...)
    (they would do pond clear out for me for only $3500-$5000...)

    This project seems to have less and less to do with 558/555 circuits the further I go...

    [ ones and zeros are so much simpler for my simple brain... ]

    william...
     
  16. hackware

    hackware New Member

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    BTW: anybody have any advice on the best component combinations which work best with 555 timers?

    a) capacitor/resistor
    b) variable-capacitor/resistor
    c) capacitor/variable-resistor
    d) variable-capacitor/variable-resistor

    Mica capacitors at 1uF and above are expensive ($4+ each) but are only 1% caps I can find...
    (multi-layer mica caps wildly alter their values with physical shock (experience talking here))...

    Tantalum capacitors seem to be more stable than common electrolytic capacitors, and don't cost much more...
    (but they have that old "explosion/burning" thing with high ripple and/or spikes...)

    Ceramic capacitors are stable over temp range, but physical shock can alter value (not as bad as multi-layer mica caps though)...

    Air capacitors (variable) work great in high static fields and/or high emf zones, and extreme physical vibration/shock...
    (but would need to seal/pot them some how)(non-magnetic, I've seen them actually mounted on transformers!)

    Don't have much experience with any of the various poly caps, same goes for mylar caps...

    Also, would the component combinations change between my needed circuits?

    1) 555 astable circuits
    2) 555 monostable circuits
    3) 555 PWM circuits
    4) 555 voltage multiplier circuits

    All the circuits above need to operate in a wet/humid environment, with thoughts of safety in a metal boat on water...
    (and physical shock without any doubt (boat paddles, transformer hum, big feet, etc...))

    I very much desire to seal and/or pot as much of the circuitry as possible, keeping in mind this might affect the circuitry operation(s)...

    With everything above in mind, I'm willing to pay more for components for stability, long life, and safety...

    Just want extra expense to be justified...
    (1% components are always nice, but not always really required, or even make ANY difference...)

    Thanx in advance to all who take the time... :) :) :)

    william...
     
  17. shortbus=

    shortbus= Well-Known Member

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    Seems like my 'microwave transformer' idea wasn't so far off base after all.:) So here's another one, how about adapting a 'fence charger'? Some circuit changes would be needed to vary the pulses but it should be doable.
     
  18. shortbus=

    shortbus= Well-Known Member

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    For your cap problem, there are some things actually called 'pulse capacitors' made for this and fairly cheap from this place, https://www.surplussales.com/Capacitors/Polypropylene/Box-Caps/Index.html The MKP type are usually called pulse caps. No affiliation just a satisfied customer. They may have some of the other stuff you need.
    https://www.surplussales.com/
     
  19. hackware

    hackware New Member

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    heh, i've used those guy b4, never thought about caps n trons tho... (mostly hydraulics / tractor stuff...)

    thanx...

    william...

    [ ps off-topic: why o why are replacement fan motors more expensive than original fan cost?!!!@### ]
     
    Last edited: Aug 4, 2017
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  20. hackware

    hackware New Member

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    yeah, gotta drag out the old microwave for surgery...

    i've built a few electric fences with ignition coils, mostly mother-earth magazine designs... nut'n fancy...

    yer microwave transformer luv goes beyond electric fence requirements tho, unless ya wanna kill sumthin... ;-)

    william...
     
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  21. crutschow

    crutschow Well-Known Member Most Helpful Member

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    1% capacitors are only needed if you don't want to adjust the timing and that's not the case here, so even 20% capacitors would be fine.
    You just take up the slop with a pot.

    For 555 circuits you want to do
    c) capacitor/variable-resistor.
    (Adjustable capacitors are only generally used in high frequency circuits).
    Most of those have a short, non-adjustable pulse width.
     

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