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air cannon controller

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New Member
hey guys i am new here and have done some minor things with circuits like
leds and small project but i recently created a pneumatic air cannon operated by a sprinkler valve. I have already created a simple 18v circuit( two 9v batteries) and a momentary switch to open the valve; however, I was looking for some help with creating something a little more fancy. Thinking about using a resistor and capacitor( i believe) to set a time interval of when the button can be pushed to fire the cannon. I wanted a master power switch with indicator led. Then after 7 seconds or so power would be ready to pass through the momentary switch ( another indicator led) and to the valve. Simply to prevent the cannon which is CO2 fed to fire before the tank has reached a present psi or on accident injuring someone. then after each fire the current to the momentary would be delayed for 7 seconds( approx).
I have tried to figure this out on my own but i figured i would ask the experts.

opinions gladly taken


Most Helpful Member
There are dozens of ways to create a delay, but for simple and cheap timing with a fair accuracy in analog terms a LM555 Timer IC is still hard to beat!

Here is the basic specs sheet for the LM555. It shows several timing setups.
For more information on 555 timer just google it.
You will probably be overwhelmed!:D



New Member
Ok after a little research on the 555 ci timer iIcame up with a couple things,

one, I will most likely be wiring the timer in a monostable, or one shot circuit.
two, it will need to run on nor more then 15v so a voltage regulator will be needed
last, I will really be needed help while figuring this out

I found a schematic used to delay voltage to a relay to trigger another circuit.(attached, the middle schematic about voltage remaining off for set delay)
I quickly made this circuit to figure it out it worked flawlessly, my time of 7 seconds was accurate and the 18 volts I had running through it went from zero to 18 after exactly 7 seconds. upon attempting to add Leds where i needed them ( master power and ready to fire indicator) the circuit began to malfunction. I also found that trying to substitute the relay control with what i needed would not work.

What i am asking is how would i modify this to achieve my above statement for an air cannon controller.


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