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FrozenGate by Avery

Single Pulse Driver Circuit

Ok got it working, only problem i have is if i hold the trigger switch on, the output stays on?

How would i make it so that if the trigger is held down longer than the pulse the output turns off?
 
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Having no memorable direct experience to advise you with (I usually use a uC for precision one-shot stuff instead of a 555 these days) I've done a bit of searching and found this:

555mono.gif

The two circuits below illustrate using the 555 timer to close a relay for a predetermined amount of time by pressing a momentary N/O push button. The circuit on the left can be used for long time periods where the push button can be pressed and released before the end of the timing period. For shorter periods, a capacitor can be used to isolate the switch so that only the initial switch closure is seen by the timer input and the switch can remain closed for an unlimited period without effecting the output.
Click to expand...

Circuits Page 9

I believe this operates the way the one djQuan posted does, did you try that or just the one in the OP?
 
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Fiddy said:
Ok got it working, only problem i have is if i hold the trigger switch on, the output stays on?

How would i make it so that if the trigger is held down longer than the pulse the output turns off?
Click to expand...

That's exactly what I said would happen on post #6. That's why I recommended a circuit I drew on post#12.
 
djQUAN said:
That's exactly what I said would happen on post #6. That's why I recommended a circuit I drew on post#12.
Click to expand...

im sorry, i read your post wrong, thanks for drawing that up djQUAN & RHD
 
that circuit rhd and djQUAN did works nicely, just simulated it on a program,

i put a 10k resistor in series with a 100k pot so the pulse can be set from 110ms to 1.1seconds and if the trigger is held closed it doesnt trigger again or stay on!


singlepulse.png
 
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made messy modifications to my first diagram to bring it up to what rhd and djQUAN drew,

works perfectly, heres the prototype in my M4

prototype.jpg
 
My Phaser "toy" nearly toasted the cheep switch.
I tried an IFR510 Mosfet and found the voltage is
too low for operation. I switched to a TIP120 NPN
Darlington BPT and it works OK. That tranisitor
has an hFe of over 1,000.
Fiddy is OK because he is over ~5 volts.
HMike
 
Hemlock_Mike said:
My Phaser "toy" nearly toasted the cheep switch.
I tried an IFR510 Mosfet and found the voltage is
too low for operation. I switched to a TIP120 NPN
Darlington BPT and it works OK. That tranisitor
has an hFe of over 1,000.
Fiddy is OK because he is over ~5 volts.
HMike
Click to expand...

haha dam, the N channel im using has a threshold voltage of 4V
 
So do mine but I figured -- "what's 0.3 volts?"
It does make a big difference. My BPT only
cost me 100 mW -- so what ---
HMike
 
dQ -----
Really !!!! Our local radio shack doesn't even know... They stock only one and I tried two others which I had. I'll look for one of those and maybe a small IGBT transistor but for now, the darlington is working.
Thanks --- HMike
 
RadioShack is a dismal afterimage of what it once was. Not only are components 500% overpriced but the selection doesn't let you do much with what's available.
 
You can find logic level mosfets in old motherboards. It will be a little hard to remove though since the boards are multilayer and would need a considerable amount of heat to remove parts.
 
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