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Timing Current Lapses

B

Bill Wayne

Jan 1, 1970
0
First of all, I apologize if this is the wrong group or if this
question has been addressed in the FAQ.

I've been interested in circuitry for a while, and am now trying to
design them. One thing in particular I want to do is create a setup
where, after a given time, the circuit *breaks*. This is to trigger
capacitors, which are connected to solenoids. I think you can guess
(or is it guass?) where I'm trying to go with this.

The 555 timer seems to be popular, but from what I understand it
rapidly flips between a low and high current. What would be a good way
to do what I intend?

Thanks in advance,
Bill
 
M

MooseFET

Jan 1, 1970
0
First of all, I apologize if this is the wrong group or if this
question has been addressed in the FAQ.

I've been interested in circuitry for a while, and am now trying to
design them. One thing in particular I want to do is create a setup
where, after a given time, the circuit *breaks*. This is to trigger
capacitors, which are connected to solenoids. I think you can guess
(or is it guass?) where I'm trying to go with this.

The 555 timer seems to be popular, but from what I understand it
rapidly flips between a low and high current. What would be a good way
to do what I intend?

No, I can't guess right now what you want to do. I am sitting here
with a glass of wine, thinking out the wonders of the applications of
the LM555. Life is truely amazing there must be a million ways you
can wire up a 555 to do a million different things. Among them are
various circuits that oscillate and make single pulses. Some of these
puses are high and can be used to tuen on a MOSFET for a brief time
others are low.

I predict that if you can be more specific, many people will give you
many suggestions. Among them will be some that will work, perhaps
after you decide to put a bypass capacitor on pin 5.

There will also be some folks suggesting that your application would
be better served by a PIC. Although these people are well meaning,
you should ignore them for that way leads to maddess. The only
microprocessor anyone should ever consider using is the 8051.
 
R

Rich Grise

Jan 1, 1970
0
First of all, I apologize if this is the wrong group or if this
question has been addressed in the FAQ.

I've been interested in circuitry for a while, and am now trying to
design them. One thing in particular I want to do is create a setup
where, after a given time, the circuit *breaks*. This is to trigger
capacitors, which are connected to solenoids. I think you can guess
(or is it guass?) where I'm trying to go with this.

Guessing is useless, so most won't even bother.

What are you actually trying to accomplish?

Thanks,
Rich
 
B

Bill Wayne

Jan 1, 1970
0
Guessing is useless, so most won't even bother.

What are you actually trying to accomplish?

Gauss gun. I thought the pun made it clear.
 
B

Bill Wayne

Jan 1, 1970
0
First of all, I apologize if this is the wrong group or if this
question has been addressed in the FAQ.

I've been interested in circuitry for a while, and am now trying to
design them. One thing in particular I want to do is create a setup
where, after a given time, the circuit *breaks*. This is to trigger
capacitors, which are connected to solenoids. I think you can guess
(or is it guass?) where I'm trying to go with this.

The 555 timer seems to be popular, but from what I understand it
rapidly flips between a low and high current. What would be a good way
to do what I intend?

Thanks in advance,
Bill

First of all, I'd like to say that I'm planning on building a coilgun.
It seems the pun wasn't as obvious as I had hoped.

In any case, it seems that what I planned won't exactly work out. A
better option instead seems to be using 555 circuits so that after
time N, the output switched from low to high and completes the
capacitor circuit that runs through the solenoid. Would this work?
Assuming it does, what would be an efficient way to recharge the
capacitor after it discharges?

Bill
 
R

Rich Grise

Jan 1, 1970
0
First of all, I'd like to say that I'm planning on building a coilgun.
It seems the pun wasn't as obvious as I had hoped.

In any case, it seems that what I planned won't exactly work out. A
better option instead seems to be using 555 circuits so that after
time N, the output switched from low to high and completes the
capacitor circuit that runs through the solenoid. Would this work?

Probably not. I wouldn't put a 555 withihn 10 feet of a coilgun. You
use a pushbutton to fire the first coil, then optical interruptors and
SCRs to time the ensuing pulses based on the position of the slug.

I'd also physically space out the coils to account for acceleration
along the barrel, that simplifies your timing requirements.
Assuming it does, what would be an efficient way to recharge the
capacitor after it discharges?

A power supply? Use enough series resistance so that your power supply
doesn't blow a fuse, and charge them as fast as you need to to be ready
for your next shot. But whichever way you do it, over the long run you'll
be expending pretty much the same amount of watt-hours.

Good Luck!
Rich
 
B

Bill Wayne

Jan 1, 1970
0
Probably not. I wouldn't put a 555 withihn 10 feet of a coilgun. You
use a pushbutton to fire the first coil, then optical interruptors and
SCRs to time the ensuing pulses based on the position of the slug.

I'd also physically space out the coils to account for acceleration
along the barrel, that simplifies your timing requirements.

I think I understand how that would work. I was already planning on
spacing the coils to optimize the end velocity, but I can see how that
would help with timing.

I'm trying to imagine how this would look in practice, though. As I
see it, some distance before each capacitor is an photodiode connected
to an SCR gate. When the sensor detects the projectile has passed over
it (probably either by detecting sparks caused by friction or by
modifying the projectile), it supplies electricity to gate and allows
the capacitor to conduct through the SCR. That seems much less
complicated than either other setup, at least in theory.
A power supply? Use enough series resistance so that your power supply
doesn't blow a fuse, and charge them as fast as you need to to be ready
for your next shot. But whichever way you do it, over the long run you'll
be expending pretty much the same amount of watt-hours.

So the supply would be connected to each capacitor. I had imagined
that could cause the gun to fire preemptively, but it seems your
recommended capacitor setup solves that problem, too.
Good Luck!
Rich

Thanks!
Bill
 
R

Rich Grise

Jan 1, 1970
0
I think I understand how that would work. I was already planning on
spacing the coils to optimize the end velocity, but I can see how that
would help with timing.

I'm trying to imagine how this would look in practice, though. As I
see it, some distance before each capacitor is an photodiode connected
to an SCR gate. When the sensor detects the projectile has passed over
it (probably either by detecting sparks caused by friction or by
modifying the projectile),

No, it's by interrupting the light beam from your emitter to your
detector.
So the supply would be connected to each capacitor. I had imagined
that could cause the gun to fire preemptively, but it seems your
recommended capacitor setup solves that problem, too.

I need to make a disclaimer here - I've never actually done anything like
this, it's just sort of a seat-of-the-pants "that's the way I'd do it"
kind of stuff.

But if I've helped you build a coil gun, that'd be a feather in my cap! :)

Thanks,
RIch
 
B

Bill Wayne

Jan 1, 1970
0
No, it's by interrupting the light beam from your emitter to your
detector.

Yes, I see how that would make much more sense.
I need to make a disclaimer here - I've never actually done anything like
this, it's just sort of a seat-of-the-pants "that's the way I'd do it"
kind of stuff.

Same. Most of the calculations I've been making have been for
optimization, and all the circuit designs I've been designing are more
intuition based.
But if I've helped you build a coil gun, that'd be a feather in my cap! :)

I'll be sure to properly attribute it. :)
Thanks,
RIch

Bill
 
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