anybody help me with a DIY co2 gun?

[spaspeckerthedull]

hi guys - long time lurker, first time poster. I have searched for a while but can't find the specific required info, so here goes

i'm currently in the middle of a conversion from airsoft to co2. I have an airsoft gun "shell" that i'm filling with my own DIY internals. I have all my bits, but am having trouble getting them to work how I want hence the need for a bit of help.

basically, i want my setup to be the same as the drozd i use to own. In the drozd, a battery powered solenoid is used to hit a button on a valve, which releases a "shot" of co2, which propels a 4.5mm bb down the barrel. I have all my bits - namely the solenoid, the valve, my barrel etc but the problem I have is that my solenoid cannot hit my valve hard enough to release the gas.

some pics of my acquired parts:

solenoid

valve - taken from an umarex walther CP99 magazine

valve internals


I have my electronics sorted out, in that a trigger press makes the solenoid operate for approx 1/4 of a second (duration adjustable with a potentiometer) the solenoid is rated at 1kg at 10mm stroke, 3kg at 0mm. The solenoid is 12vDC.

how can i get this solenoid to hit this valve hard enough? I have already tried using a weaker spring inside the valve, the solenoid still wasn't able to open it and when I did it manually (pushed it with a screwdriver!!) the valve stayed open and dumped all the co2 in one shot so it was obviously too weak to close the valve. I am using 12g co2 bulbs that I believe operate at around 850PSI.

Any and all comments or help will be much appreciated, I know this can be done as it how my old drozd worked

[jackssmirkingrevenge]

This is the Drozd circuit board. See the capacitor on the right? That discharges into the solenoid to give it its "oooomph".

Daystate airguns use a similar system: http://www.airgunsofarizona.com/Daystat ... mation.pdf

[spaspeckerthedull]

hi jackssmirkingrevenge - thanks for the reply

the board you have pictured is the drozd upgrade board, which gives full auto. There are a couple of reasons this is no good for my application - 1) I don't want full auto 2) full auto here is illegal (over a certain power) and carries a 5 year mandatory jail term. I appreciate you are bringing the size of the cap to my attention, but my electronics are already sorted out in that I have my PCB already soldered together.

I have read the daystate CDT literature before, and have met Tony (Belas) daystate CEO and electronic engineer on a few occasions as he is a regular guest at my rifle club. I understand the reasoning behind a large CAP in daystate applications, but their rifles are PCP and run at around 2600 PSI in non FAC form, hence the need for a hefty shunt of power to the solenoid

When I owned my drozd, I did the very simple mod of increasing the voltage supplied to the solenoid, the theory being that when more voltage is applied it would hit harder. It seemed to work, without having too much of a detrimental effect on the operational lifespan of the solenoid - after all it is only active for milliseconds at a time.

One thing I have noticed between the drozd solenoid and that of my solenoid is that the drozd one seems to have weight on the end of the plunger arm that strikes the solenoid? would this make a difference? I have been turning this over in my mind all day and it seems to me that the weight would act as a hammer thereby enabling the solenoid arm to hit harder? I know a few of you will now be "face-palming" and thinking jeez what a dumb-ass, but I am a complete noob at things like this. I have spent the best part of about a week reading through these forums and am coming to terms with the theory and terminology (I am currently on sick leave from my work as I have contracted pneumonia) so I am getting there slowly

My particular application does not have to use the valve that I have sourced - the reason for the CP99 valve is that I happened to have a spare one lying around!! If anyone can give any pointers to an alternative then you have my thanks in advance

The system I want to build is as follows:

propellant source is 12g CO2 bulb as I have lots and they are readily available.

I need to use an electronic trigger as I cannot use/have no room for a mechanical

I simply wish to replicate the drozd system, in that a press of an electronic trigger actuates a solenoid which will hit a valve and release a shot of CO2 which will then propel a 4.5mm lead BB down a barrel and on towards a target - eventually the gun will be used for relaxational "paper punching" down my club rifle range. I have read with interest about quite a few builds already done on here, but none seem to be specific to my particular needs. If it helps any, I haven't yet decided on an ammo feed system but am leaning towards gravity fed for simplicity - oh and before I forget, all of this system will be contained within an FN P90 shell, which I already own, hence the lean towards gravity fed as the magazines on these are on the top of the gun. As far as I am aware there have been a couple of paintball marker builds inside a P90 shell but never a CO2 bb gun

[jackssmirkingrevenge]

There are a couple of reasons this is no good for my application - 1) I don't want full auto 2) full auto here is illegal (over a certain power) and carries a 5 year mandatory jail term. I appreciate you are bringing the size of the cap to my attention, but my electronics are already sorted out in that I have my PCB already soldered together.

That was the point I was trying to make, in order to use a solenoid as a hammer, it only needs a short burst of electrical energy, but a large one - unlike a solenoid that is used to open a door for example.

I have read the daystate CDT literature before, and have met Tony (Belas) daystate CEO and electronic engineer on a few occasions as he is a regular guest at my rifle club. I understand the reasoning behind a large CAP in daystate applications, but their rifles are PCP and run at around 2600 PSI in non FAC form, hence the need for a hefty shunt of power to the solenoid

I have a FAC Mk.3 that does 28 ft/lbs, lovely bit of kit

Even though you have lower pressures and pressure areas, you still need to smack the valve, and I don't think you can do this with a low volt DC power supply without the aid of a capacitor. After all, the Drozd runs on 850 psi CO₂ and still needs a capacitor.

When I owned my drozd, I did the very simple mod of increasing the voltage supplied to the solenoid, the theory being that when more voltage is applied it would hit harder. It seemed to work, without having too much of a detrimental effect on the operational lifespan of the solenoid - after all it is only active for milliseconds at a time.

... so you know the benefits

There are for example solenoid nail guns that don't use capacitors, but these typically run off domestic AC current, not the sort of power you can carry around.

One thing I have noticed between the drozd solenoid and that of my solenoid is that the drozd one seems to have weight on the end of the plunger arm that strikes the solenoid? would this make a difference? I have been turning this over in my mind all day and it seems to me that the weight would act as a hammer thereby enabling the solenoid arm to hit harder?

That's basically the idea, increasing hammer weight increases the momentum and therefore the valve opens for longer.

I know a few of you will now be "face-palming" and thinking jeez what a dumb-ass, but I am a complete noob at things like this. I have spent the best part of about a week reading through these forums and am coming to terms with the theory and terminology (I am currently on sick leave from my work as I have contracted pneumonia) so I am getting there slowly

I have spoken to much, much dimmer individuals on this forum, don't worry and good luck with your recovery!

My particular application does not have to use the valve that I have sourced - the reason for the CP99 valve is that I happened to have a spare one lying around!! If anyone can give any pointers to an alternative then you have my thanks in advance

If you have it, use it! Saves a lot of effort certainly.

I simply wish to replicate the drozd system, in that a press of an electronic trigger actuates a solenoid which will hit a valve and release a shot of CO2 which will then propel a 4.5mm lead BB down a barrel and on towards a target.

Sorry to repeat myself, but you're going to need that capacitor

[spaspeckerthedull]

hi jackssmirkingrevenge -

I see what you're saying about the cap discharge, I don't think I can mod my existing PCB as it was a simple shop bought kit that operates a 12vDC relay when triggered with the output time trimmable with a pot, however I reckon I should be able to use/convert the board out of a disposable camera somehow? thoughts please?

i'd also like to incorporate a blow forward action if possible - again thoughts please. My other option is to simply incorporate a paintball marker into my design but instead of firing a paintball it would fire a bb - not really feasible for me as paintball markers, especially electronic ones, are expensive and it wouldn't give me the satisfaction of saying "I did that" plus it wouldn't be "heath robinson" enough for me either!!

[jackssmirkingrevenge]

I see what you're saying about the cap discharge, I don't think I can mod my existing PCB as it was a simple shop bought kit that operates a 12vDC relay when triggered with the output time trimmable with a pot, however I reckon I should be able to use/convert the board out of a disposable camera somehow? thoughts please?

http://www.evosapien.com/robosapien-hac ... apien.html

http://blog.makezine.com/2009/07/17/cam ... -coil-gun/

http://www.instructables.com/id/Disposa ... a-coilgun/

This is what you should be looking for, using a disposable camera flash circuit to make a coil gun. Essentially the latter is what you are trying to make, where instead of launching a projectile you have made a hammer.

i'd also like to incorporate a blow forward action if possible - again thoughts please. My other option is to simply incorporate a paintball marker into my design but instead of firing a paintball it would fire a bb - not really feasible for me as paintball markers, especially electronic ones, are expensive and it wouldn't give me the satisfaction of saying "I did that" plus it wouldn't be "heath robinson" enough for me either!!

A simple T magazine should be enough if you're firing spherical projectiles.

This is the logic:



As you can see, the next BB in the magazine effecively blocks the magazine so very little air is wasted provided the tube in which the BBs has an internal diameter very close to the BB diameter.

This is simpler and more efficient that having to use a blow forward bolt.

it wouldn't be "heath robinson" enough for me either!!

How quintessentially British of you

[spaspeckerthedull]

got a disposable camera, stripped it down but must have borked something 'cos after removing the flash unit I cannot get it to work/flash/charge. They are only a couple of quid so I will have to go back to the shop and get another I suppose but I think i've found a stumbling block in that the circuit (if I can get it to work!!) needs about 10 - 15 seconds to recharge? that's no good as I can't wait that long between shots?

I've posted a picture of my existing circuit, just note that I changed C2 to 1µF to bring the discharge time down to a more controllable level using a pot. Is there any way I could mod this existing circuit to give me the "belt" that I need to punch this solenoid hard enough?

Also added a very simple 12v relay diagram - is there any way this could be altered to give me the same outcome?

also - british?!? I don't consider myself british, I am English - born and bred!

[spaspeckerthedull]

OK - went back in to the disposable camera, got it working and hooked up to my solenoid but when i triggered it - nothing, the plunger didn't even move. So I upped the voltage by adding more batteries and burnt the board out. Knackers.

Have been having a read of THIS THREAD HERE of someone with the same idea/problem, but the thread seems to have gone to sleep?

I've tried adding weight to the plunger arm of my solenoid, and when the glue dries i'm going to try over-driving it by a couple of volts to see what happens, unless someone can come up with a sort of DIY hammer type affair for me to try?

This can be done, I know it can, and i'm determined to get there - I just wish the drozd wasn't so expensive to buy as I would get one and cannibalise it

[dewey-1]

I've tried adding weight to the plunger arm of my solenoid, and when the glue dries i'm going to try over-driving it by a couple of volts to see what happens, unless someone can come up with a sort of DIY hammer type affair for me to try?

You will need more than a couple of volts!
A 12 volt solenoid could be actuated by 24 volts in a low duty cycle.

You could get a 6 volt solenoid and use 12 volts.

[jackssmirkingrevenge]

I've posted a picture of my existing circuit, just note that I changed C2 to 1µF to bring the discharge time down to a more controllable level using a pot. Is there any way I could mod this existing circuit to give me the "belt" that I need to punch this solenoid hard enough?

More volts, simple as that.

also - british?!? I don't consider myself british, I am English - born and bred!

I wrote "English" first then figured out you might be Welsh and get offended so I used a wider term, seems I managed to offend you anyway

I've tried adding weight to the plunger arm of my solenoid, and when the glue dries i'm going to try over-driving it by a couple of volts to see what happens, unless someone can come up with a sort of DIY hammer type affair for me to try?

Stuff like a toy cap gun or an automatic staplercan be adapted as ready made hammers.





Another possibility if you want it to be electric is to hack one of these:



The spring piston becomes the hammer, also gives you the potential for full auto.

[spaspeckerthedull]

thanks for the continuing input -

have tried running 16vDC pulse through the solenoid with the extra weight added to the arm and had a partial success in that it hit the valve JUST hard enough to open it ever so slightly, so it looks like simple brute force may be the way. I shall get a larger battery holder soon and try it with 24vDC and see what happens

again jackssmirkingrevenge, I like the idea of maybe trying to use the original airsoft piston setup as a hammer, but as the P90 I bought was supplied with a cheap plastic gearbox I think i'll keep plugging away at the solenoid. Nice idea though, keep them coming

Also need to re-iterate about the full auto. IT IS NOT ALLOWED IN THIS COUNTRY AND IF YOU DO GO FULL AUTO IN THIS SETUP YOU ARE LIABLE FOR THE MANDATORY SENTENCE OF 5 YEARS FOR BREACH OF FIREARMS ACT SECTION 5. Apologies for the CAPS, the statement is for the benefit of any "big brothers" that may be watching

will try it a la Tim Allen (MORE POWER!!) and report back. Also, it seems that my existing electronic setup is of no use as well, reason being the 555 timer in my circuit does not start to countdown until after I release start button/trigger. This is regardless of how the "pulse" time is trimmed using the pot, because the 555 does not activate the circuit/output relay until after the release of the start button/trigger. Not an ideal setup as I am looking for a semi-auto trigger action - one pull of the trigger, one pulse to the solenoid is what i'm after regardless of how long the trigger is held down

keep 'em coming

[Goats spudz]

Im in England and i have a full auto .22 cal airgun, Most airguns made on this site are most definitely illegal.

[dewey-1]

Also, it seems that my existing electronic setup is of no use as well, reason being the 555 timer in my circuit does not start to countdown until after I release start button/trigger. This is regardless of how the "pulse" time is trimmed using the pot, because the 555 does not activate the circuit/output relay until after the release of the start button/trigger. Not an ideal setup as I am looking for a semi-auto trigger action - one pull of the trigger, one pulse to the solenoid is what i'm after regardless of how long the trigger is held down

Did you look at the schematic I provided?

It will do; one pull of the trigger and one pulse to the solenoid regardless of how long the trigger is held down.
A circuit that is over 30 years old and a proven design!

[spaspeckerthedull]

Also, it seems that my existing electronic setup is of no use as well, reason being the 555 timer in my circuit does not start to countdown until after I release start button/trigger. This is regardless of how the "pulse" time is trimmed using the pot, because the 555 does not activate the circuit/output relay until after the release of the start button/trigger. Not an ideal setup as I am looking for a semi-auto trigger action - one pull of the trigger, one pulse to the solenoid is what i'm after regardless of how long the trigger is held down

Did you look at the schematic I provided?

It will do; one pull of the trigger and one pulse to the solenoid regardless of how long the trigger is held down.
A circuit that is over 30 years old and a proven design!

I have looked at your schematic but do not know how to build it. I have a VERY limited understanding of electronics. The board I have came as a kit with all parts provided and very clear and concise instructions, ie "solder part C1 into hole 5" type of thing. Whilst I have no doubt that your design will work, unless it is available as a kit to buy with very easy instructions, it is of no use to me but I appreciate you trying to help

[jackssmirkingrevenge]

it looks like simple brute force may be the way.

That was the point of adding the capacitor, but simply getting a bigger battery is another way of doing it

again jackssmirkingrevenge, I like the idea of maybe trying to use the original airsoft piston setup as a hammer, but as the P90 I bought was supplied with a cheap plastic gearbox I think i'll keep plugging away at the solenoid.

All you have to do is give the piston a hard face, the gears are there to cock the piston and they're usually more than up to the job.

Also need to re-iterate about the full auto. IT IS NOT ALLOWED IN THIS COUNTRY AND IF YOU DO GO FULL AUTO IN THIS SETUP YOU ARE LIABLE FOR THE MANDATORY SENTENCE OF 5 YEARS FOR BREACH OF FIREARMS ACT SECTION 5. Apologies for the CAPS, the statement is for the benefit of any "big brothers" that may be watching

If big brother is watching,