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Timer circuit/555 board

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Unread postAuthor: Marco321 » Wed Oct 17, 2007 5:57 am

Here is my solution

Circuit 1: I have worked with the 555 timers before, i was trying to get an alternating positive current, there is a formula based on the resistors used to figure out frequency and time the current is on for. It worked well.

Circuit 2: Another thing you can do with them is make a wait period before the current gets sent through, the time delay was set by a resistor used, and there is a formula for working it out. The delay is created every time a current was sent through the circuit.

Circuit 3: Another thing i did was use 2 transistors, 2 resistors and 2 caps to make a circuit to light alternate LEDS, the caps and resistors determined the frequency and how long each LED was on for.

My thoughts are that you can use the a circuit like the 3rd on i described, which then alternates between the solenoid, then a circuit like the 2nd one for the 2 second delay to fire the bolt. I hope that makes sense, it does in my head and should work. Here is what should happen, the 3rd circuit i shall call the "2 cap" and the 2nd one i will call the "delay": -

Current goes to the "2 cap" when the switch is on, for a certain amount of time, current goes to the solenoid, then the "2 cap" flicks over to the "delay" which makes a 2 second delay then activates the bolt. The "2 cap" flicks over to the solenoid, and the cycle continues. And there you have my solution.

Any questions just ask :D
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Unread postAuthor: dewey-1 » Wed Oct 17, 2007 10:10 am

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Last edited by dewey-1 on Sun Apr 20, 2008 3:42 pm, edited 1 time in total.
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Unread postAuthor: jimmy101 » Wed Oct 17, 2007 2:20 pm

The original solution of just using the Lego RCX is really the best solution. It is in no way ghetto. The RCX is a selfcontained microcomputer that includes it's own power supply, memory, sensors and high current relays (actually transistors) for controlling external devices.

To build the equivalent circuit starting from a PIC, or other single chip computer, is going to require a fair amount of electronics know-how. You need a stable power supply, signal conditioners for the inputs, power transistors or relays for the outputs etc. Why reinvent the wheel when you already have the perfrect solution in the RCX?

With the RCX you can use the inputs and simple switches to confirm that a particular step has completed before proceeding to the next step.

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If I was going to build a circuit to do this control, I would start with four 555 timers similar to Dewey-1's approach. Or, a pair of 556s (two 555s in a single package).

The first timer would control the overall cycle rate and would be a bistable, that is, it would put out a square wave at the gun's ROF.

The second timer would trigger from the first but be a monostable, it would control the duration of the first relay's cycle and trigger off the first timer.

The third timer would also be a monostable and would control the delay for the second relay and trigger off the first timer.

The fourth timer would also be a monostable and would control the "on time" for the second relay and trigger off the third timer.

You also need a power supply and the output relays or power transistors to handle the current needed by the ...

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The RCX really is the best solution.
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Unread postAuthor: Marco321 » Wed Oct 17, 2007 8:37 pm

dewey-1 wrote:marco;

Are you referring to what is called cascading timers?
The three timers would be set up as monostable operation.

Note: The times of duration are for example use only!

Timer 1 would be for the Main Solenoid with a duration of 250 ms, after it has timed out, it would trigger Timer 2.

Timer 2 would be for the Delay with a duration of 2 seconds, after it has timed out, it would trigger Timer 3.

Timer 3 would be for the Bolt Solenoid with a duration of 500 ms, after it has timed out, it would trigger Timer 1. So long as the firing trigger was still actuated this will repeat the complete cycle. Once the firing trigger was released, you would still get a complete "loading cycle".

I believe this is what shownomercy wants to do.
Please correct me if I am wrong.

For a free schematic cad program check this out:
http://www.expresspcb.com/ExpressPCBHtm ... ftware.htm
This is one way to exchange and show schematics of circuits.
Helps to explain how to show designs of circuits from members.
dewey-1


Yeah thats what i was trying to say lol. I have no idea what they are called, like i said, its been a few years....
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