Few hundred ms delay circuit

[xoo1246]

I had an idea for a circuit to be used with two detonators in a FAE test. Let me point out that I'm not a at all skilled when it comes to to electronics. This is where you come in. <img border="0" title="" alt="[Wink]" src="wink.gif" />
Here it is:
<a href="http://w1.478.telia.com/~u47802930/circuit.jpg" target="_blank">http://w1.478.telia.com/~u47802930/circuit.jpg</a>
No resistance, voltage or capacitance is marked since I haven't done any calculations. The questions is, would the general concept work with the right components to give a delay of a few hundred ms?
One could hook up a timer to to D1 and D2 to measure the time between their activation.
Hmm, time to go to bed. Hope this post was constructive.

[Einstein]

I think it could work....one of my hobbies is electronics, so that should do. Finding right components is is a task: calculate, buy, test, calculate, buy, test, ...etc etc etc....

It would be good to get delay detonator for FAE, because I read from somewhere (forum?) that buildings and ships were destroyed with 60kg of flour detonated with small charge and then after 10-30ms later sparkling charge were detonated, which ignited flours.

[McGuyver]

I think the key for your circuit is going to be a capacitor. Some capacitors take anywhere from maybe 1 microsecond to a few seconds to charge to full capacity.

If you had some kind of voltage sensing device- either a transistor or whatever- that would only turn on when the cap. is at it's peak voltage- that might work.

Another idea is of course using some kind of countdown timer device. I'm sure there are timers that operate at 1/100th of a second.

[xoo1246]

There is a simple simulation program called "crocodile clips", once I had it, but since I've changed computer and didn't back up I don't have it any more. Handy little program, anyone got it?
If one got acess to a camera with reasonable frame-rate, one could calculate the aproximate fuel concentration in the air depending on time by looking a the diameter of the fuel cloud formed after the burster charge has detonated(knowing the amount of fuel in your container preferably :p ).

[pyromaniac_guy]

or you could determine most efficent time delay by the goof old fashioned (and much more fun) trial and error method :)

[nbk2000]

This topic is well timed.

I was just reading a patent (US#6244184) for a bomblet fuse that uses an accelerometer to detect when the bomblet hits hard vs. soft targets. Hard targets (tanks) get SQ fuze action, while soft targets (ground) get a bounding charge explosion which launches the bomblet back into the air where it explodes a few hundred milliseconds later as an airburst for increased effect against infantry.

Now, the SQ fuze is easy, and so is the bounding charge. The thing that stumps me is a simple means of delaying a few hundredths of a second.

Since I'm not planning on attacking tanks, all the bomblets would be bounding airburst. Are you planning on breadboarding this circuit for testing? Because a simple circuitboard as diagramed could be made by the hundreds easily and cheaply.

As an aside, the patent uses a capacitor to store the needed charge to detonate the bomblets. The cap. is charged in flight from an onboard battery so the bomblets are unenergized until immediately before dispensing, making them safe to handle. Also, since caps self-discharge over time, this renders safe any bomblets that failed to explode within a few minutes.

I'm wondering, would it be easy to use disposable camera flash caps as the initiators? I'm thinking, if the bomblets are filled with plasticized AP, then you don't even need a detonator, just a fat hot spark. Such as when a flash cap is shorted out. :)

What kind of circuit would be needed to charge up photocaps by the hundreds, all at once? Is it doable? If not photocaps, what kind of caps could be used?

[xoo1246]

Couldn't you use the standard charge circuit found in the photo flash. Using a transformator in combination with a pulse generator? Then connect several caps paralelly. I assume what stopps the charging is when the resistance increase in the cap(s). True?
You would have to change the common 1.5 v batteries to something capable of giving more amperes if you don't want to wait forever when charging.
I see no reason to use hight voltage capacitator if you don't want to use exploding bridgewires.
I'll try to get hold of that program, or I will have to calculate this manually. But since I have many things going paralelly I will either forget about it or it will take time.

[Flake2m]

I was thinking that you could use a 555 astable circuit. The 555 astable continuly switches on and off, it can run on a 9v battery and could be re-used again. The speed of the 555 can be changed by using different capacitors and resistors. You could use the 555 to run a relay or a transistor.