venture51

The diode is likely why your frying your mosfet, connecting the positive and negative is never good even with a diode (you could also have the diode running the wrong direction too)

​You can see the diode in the photo above - it appears to be in the correct direction.  The motor ran ok for a while even with it on there.   Other than the ball timing/double/triple shoot, the gun was spinning up and shooting well... until it failed.

I read that having the diode  was critical for protecting against reverse voltage nd have seen them on multiple designs.  I've seen airport schematics without one - so I don't know...

Just before the mosfet failed the motors did not spin up - I think they seized... then began to smoke before I pulled the battery.  The next time I plugged in the battery after that, the mosfet had failed, and the motors spun up automatically even without the high signal.

You should post up a wiring schematic for us to look at and try to help you find the problem, it seems to me you may need registers or possibly a step down style regulator for the mosfets, but without a schematic it's hard to say.

My wiring diagram is written in pencil on a sheet of notebook paper - it's quite the mess.  I'll clean it up and post it. 

In the meantime, I mentioned that my schematic is roughly based on TG's Rapidstrike schematic though.  The area I'm concerned with is the two flywheel motors - I've got mine wired similarly.  It has 12 volts supplied directly with the battery, a diode across the negative and positive leads, and a single mosfet on the motors' negative leads.

So I was inspired by F4S4K4N to create my own "CronOS" mod (which I'd probably dub "CronOS" lite) and was going to wait until I had it working really well before I shared my work with the community.   However, I ended up running into a few issues that I'm hoping you all can help with.

I made a number of changes to the original CronOs mod - both in the hardware and software.  I built my version without any instructions, but based it on a modified version of Technician Gimmick's Rapidstrike schematic http://nerfhaven.com...apidstrike-mod/.  I replaced the pusher motor in his schematic with a solenoid, and removed all the additional switches, displays etc.

3D Printed Parts and Analog Trigger

​Among the biggest changes I made was in incorporating 3D printed internal parts to create a battery, custom board, and Arduino cages - as well as fitted parts for the firing solenoid and an analog trigger.  The analog trigger is a sliding pot.  When the trigger is partially pulled, the motors spin up, and once the trigger is half way, the solenoid actuates.  What this does is eliminate the need for two separate triggers, you just pull the one.  I'm eventually going to have a mode where when you pull it part way you get a single shot, and when you pull all the way, it switches to full auto.

Simplification of the CronOs build

I also opted to remove the safety and "Quickfire" buttons - which I thought made the build unnecessarily complex.  ​(The mode switch is recessed enough that I believe the chances of accidentally changing modes to be very low).  I ended up having trouble compiling F4S4K4N's original code (I'm not a programmer in my day job - so couldn't figure out why it wouldn't compile in Arduino 1.7) - so I flattened the code into a single file and removed all the IFDEF statements.

​I've completed an initial build, but ran into the following problems:

BUGS

​1. In semi-auto, I can't seem to get the gun to consistently fire just one ball.  With the IR sensor - it would fire 2-3 balls.  Using the IR sensor didn't seem to solve this problem - in fact it appeared to exacerbate it.  I found removing the IR code, and relying on just the timing was more reliable (but I'd still sometimes get 2 balls instead of 1).

​2. My bigger problem right now is I've fried the mosfets hooked up to my flywheel motors twice now.  I did a little research, and I believe that the mosfets I chose (IRF520) were insufficient to handle the feedback from the motors.  Originally the flywheels were spinning up fine, but the motors stopped responding, spun weakly, and then it appears the mosfets overheated and immediately shorted, causing the motors to spin up indefinitely (only stopping when I turn the power switch off or pulled the battery).

I think I need something more robust.  I also think I might need protection circuitry and/or a heat sink for the mosfet.  I'm not an engineer, so I'm hoping that one of you is - and can advise me on how to fix the problem.  I came across this setup on an airsoft site:  http://www.airsoftca...ead.php?t=89097 - I think the components listed should take care of the problem.  My understanding is it will allow for higher peak currents.

​I've got the parts listed in the airsoft site on order, and am going to try replacing the mosfet/motor portion of the circuit. 

​Here's a picture of my build - would love your suggestions on how to solve the problem - or any questions or critique of the build.

- Venture