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flippityflop

timer to trigger latch

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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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How large an electromagnet are you using?


figure i'd be making the core from electrical steel bar about 2.5 cm x 0.3cm x 0.3cm (salvaging from strips off a small transformer)... something like that. has to be small and light.

basically press the toggle switch... 1, 2, 3.... hinged mechanism snaps close.

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i am using a coil. it's just that the core will be made from electrical steel.

those small transformers are made out of sheets of electrical steel, right? i'll just cut them up and stack them together again to get a bar as a core

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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.

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what specific part do i need if want a solid state relay that is normally open, dpst, and is operated by a current that has a very large gap to switch on or off... (by the last requirement, i mean if the normal off current is 0, the on has to be 100mA... or 10mA - 1 A. or something like that.)
also has to be cheap.

thnx!

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Why? What are you trying to do?

Your discription is very vague.

The current though a relay's contacts will depend on the load.

Or are you saying you need a current to activate the relay, i.e. when the curerent exceetds 10mA, it turns on?

You'll also recieve more help if you post a schematic.

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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.

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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.

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Threads merged. Don't create multiple topics about the same subject - it wastes our time and yours.

We still don't know what you want. An electromagnet is inductive not capacitive.

You've posted a coupled of standard 555 timer schematics, not your problem.


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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.....

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@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.

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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?

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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.

index.php?action=dlattach;topic=22577.0;

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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.

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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

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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.

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