using solenoids

[igpay]

I'm looking to make an pump airsoft sniper rifle using a solenoid valve and I had a few questions:
First of all, is this even worth the trouble? I'm only attempting to use a solenoid because i've made an airsoft gun out of a water gun before and i didn't like how you had to pump it 20 times after every shot.(i'm lazy)
Next, I haven't heard of any mentions of this on spudfiles, but i think it should work if i use a capacitor to trigger the solenoid. I don't have much experience with electronics but i think that it should discharge all of its electricity at the same time, only opening the valve for a short period of time so as not to let all the air out.
I'm working on a picture right now.
thanks,
igpay

[jackssmirkingrevenge]

You should look into modding your solenoid valve for pneumatic actuation, it's very simple to do and will give you increased power and remove your dependence on batteries and fiddly electronics.

[Carlman]

ohh lol, i was thinking of him just using the actual solenoid somehow

[igpay]

But if i did this, wouldn't i still need a separate valve to trigger this one???
Sorry, im a noob.

[jackssmirkingrevenge]

But if I did this, wouldn't I still need a separate valve to trigger this one?

Yes, a very cheap blowgun available from practically anywhere

[igpay]

Well, I'll consider that, but still, what if i wanted to use a solenoid? Does spudfiles have a resident electrician or something like that who could help me?

[XxtriviumxX]

You dont have to tell us when you log off

is this even worth the trouble?

Yeah, a solenoid gun isnt to much trouble really, simple and effective ...

You should probably read through this first
http://www.spudfiles.com/forums/modding ... -t305.html

[psycix]

A capacitor that is like 400 volt will instantly dump its whole charge trough the solinoid.
But if you have got a 24 volts solinoid and a 24 volt capacitor it will gently give the right amount of power until the capacitor is empty.

[igpay]

thanks!
but how long would the valve stay open if i only used 24 volts?
isn't voltage the measure of how much energy a capacitor holds?

[igpay]

thanks for all the help you guys!
But actually, i think i'm just going to make a simple breachloader with a ball valve.

[psycix]

http://hyperphysics.phy-astr.gsu.edu/hb ... apeng.html

Use this to calculate the amount of J stored in your cap.
Then you can use the amount of watt used by the solinoid to calculate how long it will last.
1W = 1J/s

[igpay]

Thanks for the help, but as i said before I doubt I will use a solenoid.
I want something simple for my first gun.

[Hotwired]

A solenoid cannon IS simple

Solenoid is wired up just like a lightbulb with a battery and switch, switch goes on, solenoid valve opens.

Easy as pie


Plus once you're happy in how it works like that you've got the option of upgrading it with a pneumatic trigger which isn't much harder to do.

[psycix]

In fact, a blowgun trigger is easier.
Pull it and your valve is open.

[jimmy101]

A solenoid works OK for a small bore gun such as airsoft. I would think a blowgun would be overkill for the trigger.

Here is a BBMG made from the water supply valve from a washing machine.


The capacitor really isn't needed, a switch and a battery work fine.

If you want to use a cap so the valve will cycle open then closed you'll need circuitry to control the charging of the cap. Not terribly difficult for low ROFs, gets complicated at high ROFs.

I would think it would take a pretty big-ass cap to supply enough power for long enough to cycle the valve correctly. A typical photocap (~120MFD) probably won't work but might be worth a try at voltages starting at whatever the solenoid is rated for and going up from there. (You can run the solenoid at higher than rated voltage for short periods of time.)

In the circuit below if the Solenoid coil is 10 Ohms and you want the valve to stay open for 0.1 second then the RC of the circuit needs to be ~0.03 seconds and the capacitor needs to be about 0.03sec/10Ohm = 3000MFD. That's a very big capacitor. Boosting the voltage will allow you to use a smaller cap but it'll be harder to come up with a suitable power supply.