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flippityflop

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Posts posted by flippityflop



  1. With all the series diodes feeding emitter-followers and the fuse then there is no voltage regulation.
    It has the LED shown backwards which shows how much that site knows about electronic circuits.

    The rectified and filtered 30VAC produces +40V. If the output is shorted or the voltage is set low and the load current is 20A then each of the 4 2N3055 transistors must dissipate 40V x 5A= 200W which is absolutely impossible.


    crap. bunch of liars, they are.

    i can just go with this:
    http://electronics-lab.com/projects/power/001/index.html

    but 3A MIGHT NOT BE ENOUGH....

    can we tweak it a bit or make improvements in the design so that it can reach around 6A?? bit too much to ask.. but is it even possible?

    if heat dissipation really is an issue, i can level all the ICs that needs cooling and just mount a single large copper plate or something and attach a dc fan....

  2. been scouring the web for a good diy dc power supply that can power a lot of my experiments.
    so this is the what i settled on:

    http://www.eleccircuit.com/high-power-supply-regulater-0-30v-20a-by-lm338/

    so, does anyone else know of a better design??
    i really don't have the knowledge to analyze if it's reliable or have a lot of noise... that and i don't want to spend hours, scouring the web, you see...

    if there's even a remote chance of this being overloaded, i'd like to add (if it isn't already there) a current limiter.... can it be easily integrated to this design?




  3. If you spent the amount of time you've spent trying to come up with an inferior design yourself working you'd have the money to buy it by now.


    unfortunately, money is an issue and buying that $150 thing is too much of a luxury.

    and, no, i have not spent weeks coming up with these things -- though saying that might not be a good thing, as it automatically suggests that. it's what i read-on and scour the web (for parts) when i'm bored or can't sleep.... or something. so it really is something that i don't prioritize, more like afterthoughts; as are other projects that i've started almost a year ago that still ain't done...

    with the exception of my programming projects, that is.

  4. can't find a proper latching switch that goes to being open after the power has been cut-off (reset?). so i changed the design on parts that i can easily obtain.


    i'm not really sure with it. i have these 2 unknown component that are lock-off devices -- if current goes to the gates, it OPENS, BUT it has to do it EVEN IF THERE IS NO CURRENT FLOWING THROUGH THE ANODE AND CATHODE YET AND MAINTAIN IT FOR AT LEAST 7-10ms ... though i haven't actually heard of such a device.

    and i'm trying to discharge C1 so for the next cycle it'll work glitch free, and that discharge should also keep the current going so as to let 5ms pass and completely switch the latching relay.

    i wanted to change the N/O DPST relay to a solid state device... (a FET, maybe???), one that is still small. what's the lowest voltage that this control circuit can operate reliably (6-9 V??)

    i've also omitted the diodes that protect the relay, hope that's ok.


    parts that needs consideration:
    C1 = 47uF to 220uF

    latching DPDT relay:
    http://www.nteinc.com/relay_web/pdf/R72.pdf

    latching push button (still not final, it's too big):
    http://www.galco.com/scripts/cgiip.exe/wa/wcat/itemdtl.r?listtype=&pnum=AB6H-A1-R-IDEC

    N/O DPST relay:
    http://www.nteinc.com/relay_web/pdf/R74.pdf

    the fictional unicorn-like components ?? (1) and (2):
    what are they and can i get them small and cheap?



    post-44241-14279144319754_thumb.png


  5. alright... the intent of my device, though it sounds silly,  is this:
    http://www.canadiantire.ca/AST/browse/6/Tools/WeldingSoldering/AccessoriesRodsWire/PRD~0580037P/Lincoln%252BElectric%252BAutodark%252BFlame%252BThemed%252BWelding%252BHelmet.jsp?locale=en

    i can't cough up that much for some auto-darkening thigamajig.... though i like the idea very much. it should give me enough time to position my 2 hands before i make the contact when i'm arc welding.

    so i thought that if i bought a simple welding goggles for about $10, maybe i can attach an electronic mechanism to it that. so when pressed, should give me enough time to position my hands (though it'll require a bit of practice). 1, 2, 3 then it'll snap down the dark lens and i can make the electrode come into contact.



  6. press push button 1 and it switches the time delay control circuit on. for practical purposes, the high capacitance capacitor for the electromagnet will always be in parallel (ON) with the source, so that no charging time is needed.

    press push button 2 and it starts the time delay circuit. 1, 2, 3... :
    1) shorts the high capacitance circuit through the electromagnet coil, snapping the hinged mechanism.
    2) turns off the control circuit.

    the device may be turned on again with push button 1.



    the "high capacitance capacitor", above, when shorted, is what supplies the power for my external electromagnetic coil; snapping a hinged mechanism.

    i know i sounded non-sensical. i tend to do that every once in a while.  ;D


  7. Just looked at the last circuit with two transistors.

    Whn the power is applied C2 will charge causing the horrizontal transistor (I'll call it Q2) to turn on. The vertical transistor (I'll call it Q1) will then turn on  as C1 will charge. The relay will be activated shorting out C2. When C1 is fully charged, Q1 will turn off, de-energising the relay causing it to open.

    The only wat to reset the circuit is to press the start then the on reset or the reset then quickly press the start before C2 recharges.




    cool. so it works glitch-free, then, huh? and after the whole cycle (after it shorts the control and turns itself off), the whole circuit absolutely doesn't draw any more power, right?

    btw, is there any way to lower the voltage to just about 3-5V?? i'm thinking of only using rechargeable batteries, you see.

  8. this is my mod...

    i'm thinking C1 = ~70uF and C2 = 10 uF....

    would it work??


    of course, the TIP32 (<- 1st time i've seen a transistor like that, really) on the top would still be drawing power. and to avoid that, i'd have to replace that section with the latching relay again and that would also mean i would need a non-debouncing circuit again....

    well, at least when it comes down to that, it'd still be smaller than my original mod.

    post-44241-14279144314421_thumb.png



  9. What do you mean both circuits????>? One circuit will do the job.
    1 Transistor two resistors and a 47uF capacitor..
    Just a push switch not a toggle the timer begins when you let go of the button if you push the button again durring the cycle it resets the timing cycle.


    i'll edit and combine the 1st and 3rd circuits so to point out what i meant -- i could be wrong, of course. but i'm basing this on my assumption that the 3rd circuit cuts off the output supply after the button is pressed.

    i haven't picked which schematic editor and/or SPICE simulator to use yet... so i'm doing it the pbrush method, so it's gonna take a while.


  10. Try it!! KISS Easy Easy Easy 4 extra parts Whoopdy dooo


    well i pretty much get the GIST of the above diagrams.

    and really can't do the calculation or math, but i can see that when assembled together as a control circuit
    (i guess i'll pick the PNP version??)....

    i can use a dpst switch for both circuits... press it... 1, 2, 3... turns on the controlled device -- (the electromagnet powered by a high capacitance capacitor), thanks to the 1st circuit... and the 2nd circuit below, can be set to time in a slightly longer delay. then turns off 1st circuit. but i need to get that whole control circuit running again.... so is it simply a matter of putting another reset push button in parallel with the switch on the 2nd circuit?

  11. @hotwater:

    call me silly, but i take it that my mod works, just that there are no "non-debouncing" button out there so i have to build it out of another 555?....


    pfffttt... then the circuit just got bigger. had to be small.


    ok.... if there are other packages out there that does what i asked (and possibly even has less power requirements), even if it's more pricey, i'd buy it.


  12. will MY mod produce the functionality that i outlined above?
    if so then i need to know parts numbers for the relays and non-debouncing push button, if it even exists. the s1 latching button should ideally re-open when power is cut-off.

    a bit idiotic to ask, but is it even possible for this to run under 3V?

    http://img820.imageshack.us/i/mymod.gif/

    my fear is that this will end up more than $20... nooooo.....


  13. ok, i guess there's no harm in stating the full functionality of the device... (i didn't say so as it seemed silly)

    press push button 1 and it switches the time delay control circuit on. for practical purposes, the high capacitance capacitor for the electromagnet will always be in parallel (ON) with the source, so that no charging time is needed.

    press push button 2 and it starts the time delay circuit. 1, 2, 3... :
    1) shorts the high capacitance circuit through the electromagnet coil, snapping the hinged mechanism.
    2) turns off the control circuit.
    optional: short the 1uF capacitor on the control circuit.

    the device may be turned on again with push button 1.


  14. http://www.electronics-lab.com/forum/index.php?topic=22577.0

    the above is just the rough sketch....

    ok, i guess there's no harm in stating the full functionality of the device... (i didn't say so as it seemed silly)

    ok. press push button 1 and it switches the time delay control circuit on. for practical purposes, the high capacitance capacitor for the electromagnet will always be in parallel (ON) with the source, so that no charging time is needed.

    press push button 2 and it starts the time delay circuit. 1, 2, 3... :
    1) shorts the high capacitance circuit through the electromagnet coil, snapping the hinged mechanism.
    2) turns off the control circuit.

    the device may be turned on again with push button 1.


  15. ok, if i get the explanation on the main page correctly i want to base the trigger on this circuit:
    http://home.cogeco.ca/~rpaisley4/LM555Delays1.GIF
    (i'm referring to circuit #1, ignore #2)

    what's the cheapest way to rig  this so that it will short a high capacitance capacitor (about ~30 mf, ~50V ???) and temporarily supply a current through coil to snap the latch.


  16. i need to have a really small timer circuit that would trigger the closing of a hinged mechanism. not much, but i want it snap shut really fast.

    so i was thinking of using a simple electromagnet that would pull back the hinge.

    the timer has to be small and can be very crude. i'm not asking much out of it but to give me about 3-5 seconds delay before "closing" the circuit for the electromagnet. also, since i want it shut really fast, i was thinking maybe i need to provide a high power "flash" of current (sort of like those circuits from disposable cameras).

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