electronic help plz

[evan_ellerbe]

i have a circuit i made. It includes a 12v battery a small switch and a linear solenoid. im using it to forcefully trip a sear pin in a paintball gun. my problem is the setup is very direct. If you hold down the switch the solenoid stays in a excited state.I need the circuit to stop supplying energy to the solenoid after like a split second or so(even if the switch is still being held)and then when the switch is released the system resets ready to trigger the solenoid again. because if the solenoid is on for to long it makes the recocking mechanism malfunction.im really stumped here because my understanding of electronics is limited to on/off circuits.if anyone can help plz?

 

[kjennejohn]

Hi. I Googled "LM555 circuits" and found this site:
http://www.josepino.com/circuits/index?555_circuits2.jpc

Look at the first circuit on this page, the relay controller. You may be able to swap out your solenoid for the relay if it doesn't pull too much current. If not, then use the circuit as is, or use a transistor to replace the relay, but change the resistor and capacitor at pins 6 and 7 to something more suitable. These values in the circuit will keep the relay on 3 minutes or so, and you only need a quick pulse. Try 100K for the resistor and 4.7microFarad for the capacitor. If that's too long, decrease the resistor's value by a factor of ten and see if that works. If that is too long, then decrease the capacitor by a factor of ten. Continue doing this, first the resistor then the capacitor, until it works for you.


The LM555 is a timer IC. It is commonly used in all kinds of timer and oscillator circuits. There are plenty more circuits and data sheets for this online. Do your own search, perhaps on paintball gun control(lers).

Happy holidays!
kenjj

 

[evan_ellerbe]

thnxs for the post. i just wnted to know is there a simplier way?

 

[Voltboy]

555's is one of the simplest ways.

 

[evan_ellerbe]

well ive been experimenting. i made two circuits attached to one three pin switch. in one of the switch positons its attached to a capacitor charging circuit(includes battery and 16v 6800uf capacitor) then the other switch positon attachs the charged capacitor to the solenoid only which discharges it. my problem is for the charge time(like a split second) the capacitors just puting out a pulse thats a little less than i need.
should i use a higher/lower voltage capacitor or higher/lower uf capacitor or some kind of combo of both?

 

[audioguru]

Without using a transistor to boost the current then a capacitor directly driving the solenoid must have a huge capacitance (uF).

A capacitor with a low capacitance can drive a transitor for a timing period as long as you want.

 

[evan_ellerbe]

thank u canada