@jgrupczy
Don't give up on me I have a date with a garbage disposer.

 

@jgrupczy
Don't give up on me I have a date with a garbage disposer.

Are you kidding... you are my only HOPE! I am here at your beck and call! Good luck with the garbage disposer

 

Don't give up on me, either ;-) I simply have lots on my plate at the moment - as I have for the past year or so. However, this is not only interesting, but for a very good cause.

I have ideas for a microcontroller version. A microcontroller adds functionality that would not be terribly practical to implement via simple logic/timer ICs; as it would require quite a few of them and if a mistake were made, it could be expensive/impractical to change the circuit. There is also the number of connections necessary; each one is a possible failure point, and you're not that far from the Gulf of Mexico. Basically, it's a corrosive environment.

Rather than slowing the cyclic rate to avoid overheating, it would be more realistic to have the cyclic rate of fire to be close to the original, but limit the number of "simulated rounds" fired over a period of time. For example, the original M-16 and M-16A1 rifles used by the Marine Corps had a cyclic rate of fire of 750 rounds per minute. With a 30 round magazine loaded and the trigger held down, the last bullet would leave the barrel before the 1st cartridge case hit the deck (ground). This resulted in overheated barrels and wasted ammo with the most junior troops, so the M-16A2 came out with a 3-round "burst" mode; for each pull of the trigger, three rounds would fire.

This same type of idea could be easily implemented in a microcontroller solution for the simulator. For example, when the session first starts or the gun hasn't been fired for awhile, each burst might fire 6 or 7 simulated rounds at the standard cyclic rate, and then pause for several seconds before the next burst. If the operator attempts to sustain a high rate of fire, the microcontroller automatically reduces the number of "rounds" fired in a burst, and increase the length of pause before the next multi-round burst.

You might consider purchasing solenoid valves which have a larger internal passage to decrease the gas charging time.

 

Hello ronv, I hope you took my response as an attempt to be humorous. I surely understand and appreciate your time and efforts. As soon as we come to a final agreement on a solid design, I will pass it on to the USS Alabama Restoration Committee and go from there. I am one of four volunteers that spend 3 to 5 days a week working on the ship. I am also a member of the Living History Crew. The retrofitting of the Oerlikons is one of my major tasks at this time.

AND Hello SgtWookie and djsfantasi, I am also surely going to pursue a microcontroller design. One reason is to become familiar with the new tools that are available today. It has been nearly 20 years since I have done anything like that... and MUCH has changed, I am sure. My old expertise was designing systems around the original Motorola 6800 and programming in assembly language. It took editors that had to reside on mainframes....etc... Where do you recommend that I start?

 

I am an Arduino user. But, in this case (vibrations, electrical noise, cost), you may want to consider a PIC solution. You'd likely program in C or C++. On the Arduino, there is a free IDE for writing your code, compiling it and uploading it to the Arduino.

I expect something similar to the IDE exists for the PIC. Sarge?

I showed you some simple Arduino code for your timing sequence above. The nice thing about a microprocessor solution is that if a sequence changed, there is no change to the hardware. The example you quoted re; limiting firing under certain circumstances would be easy in code with no hardware change.

 

Hello ronv, I hope you took my response as an attempt to be humorous. I surely understand and appreciate your time and efforts. As soon as we come to a final agreement on a solid design, I will pass it on to the USS Alabama Restoration Committee and go from there. I am one of four volunteers that spend 3 to 5 days a week working on the ship. I am also a member of the Living History Crew. The retrofitting of the Oerlikons is one of my major tasks at this time.

AND Hello SgtWookie and djsfantasi, I am also surely going to pursue a microcontroller design. One reason is to become familiar with the new tools that are available today. It has been nearly 20 years since I have done anything like that... and MUCH has changed, I am sure. My old expertise was designing systems around the original Motorola 6800 and programming in assembly language. It took editors that had to reside on mainframes....etc... Where do you recommend that I start?

Thank you. I had forgotten how much fun it is to lay under a kitchen sink.
Here is another set of simulations that look pretty solid.
I'm no micro guy, but I'm sure there would be less hardware involved.
You still need to be careful there are no holes in your code.

 

I expect something similar to the IDE exists for the PIC. Sarge?

You are correct. The more modern one is MPLABX. There are also free C compilers. ronv is also correct that it would mean alot less hardware, though I hate to admit it.

I also want to tell the OP how much my wife and I love going to Fairhope, and visiting the USS 'Bama. I'll hep out in any way I can with your project.

 

You are correct. The more modern one is MPLABX. There are also free C compilers. ronv is also correct that it would mean alot less hardware, though I hate to admit it.

I also want to tell the OP how much my wife and I love going to Fairhope, and visiting the USS 'Bama. I'll hep out in any way I can with your project.

It's slow enough it could probably be done with a basic stamp. I think you can buy the whole kit for 50 or $60. Print out the book and away you go.

 

FWIW, I use the PIC debug board for quick and dirty projects. They run around thirty five bucks for the board and populated uC. It's overkill for a project like this, but quick and cheap. That is, if one already has a programmer. Add fifty or so bucks for that.

 

It occurs to me that a median between the high parts count of the 555 solution, and the low parts, but programming requirement of a uC, there is a possible solution that uses a CDfourty-sixty {sorry, my numeric row is still not working, I have a keyboard on order} and some decode logic. We can pursue that solution too, if you like,

 

Hello Brownout, ronv, djsfantasi and SgtWookie...

I completely understand the 555 circuit that ronv has designed. Don't tell anyone but I had to go back and look at a the 555 specs. Some of the driver circuit devices are new to me but I expected that and would be used irreguardles of what controlled them like a microcontoller. Thank you so much ronv. Curious, does your design tools generate a parts list?

Right now you guys have my head spinning. Not sure where or which way to go for a micro design down the road? I am intimately familiar with a micro controlled system that I was designing nearly 30 years ago. No knowledge or experienced with the latest or greatest. I want to pursue that route because it just makes common sense in the long run. And, because I just want to learn it! Now I have heard at least three possible routs to go but if you guys were in my place, where would you start?

I cannot thank you all enough for your help and support. This is a fantastic forum...

 

I'm not suggesting or promoting the PIC board, just using this as an example. The board comes with a PIC microprocessor soldiered to it, with the I/O pins connected to plated thru 'vias' to which one can soldier wires. All you would need to add is a regulated three.three volt power supply and the wires. Then, we'd need about twenty to thirty lines of c-code, a couple switches and we're done. Of course, we need a programmer to transfer our code to embedded flash memory.

There are other platforms which are just as capable. I don't keep up with all of them. More are added each day.

 

I don't think the Arduino can drive the propane and O2 valves directly, so an Arduino shield is called for.
Here are two possibilities to look at. You can also build one for yourself, it's not difficult if you can solder.
https://www.sparkfun.com/products/10618
https://www.sparkfun.com/products/12959
There are lots of options, and these were just the first few I found.
http://shieldlist.org
Also, for extra credit, add a display shield to the top of the stack to show the settings, error messages, or just "BOOM!".

 

I don't think the Arduino can drive the valves directly and never intended to suggest otherwise! External drive circuitry is necessary. And @Brownout , I think the PIC board would need driver circuitry for the outputs as well.

The Sparkfun products would satisfy that requirement, or one could design a circuit and PCB of your own.

I also consider the layout of the solution. A microprocessor on one PCB board, connecting to multiple PCB boards is an inelegant solution. I'd go for everything on one board, power supply, I/O, output drivers, and microprocessor.

 

On the micro side. There would need to be some input method to change the fill and cool times.

 

Interesting project!

You can also use a PICAXE. This is s PIC microcontroller, which is programmed with a Basic like language. It has a lot of potential, and the IDE is free and easy to use.

 

Hi, I don't have much technical expertise to contribute, but reading the thread it occurred to me; given that the environment mentioned is going to be harsh (salty gulf air, vibrations from the firing, etc)... it might be a good idea to design this for a cheap uC. This way you can buy and preprogram a couple of them in advance (along with any necessary peripherals such as drivers/shields) to have safely tucked away somewhere. Then if a controller or accessory fails, practically anyone can start swapping parts to test what died, just swapping like for like without needing any specialized expertise -- if they can remember (or write down) "the red wire connected to the second pin from the left on this little blue board" a swap should be pretty easy for most people.

 

Just getting some thoughts down:

Those solenoids have 7 Watt coils, so operating on 12v that would be about 21 Ohms resistance and about 0.6 Amperes current. As I suggested before, increasing the internal aperture to 1/4" would allow greater volume of gas flow, thus requiring less time to fill the barrel. It would be a good idea to consult with the manufacturer as far as which type of seals wold be best for propane and oxygen.. I suspect they may recommend options 2 and 6.

Also, simply using a diode across the solenoids' coil would result in slow valve closure times; adding a resistor in series with the diode would cause the current flow to stop much more rapidly, thus collapsing the magnetic field faster and allowing the valve to close rapidly.

A copper propane line might be wrapped around the breech, providing some cooling to the barrel. This would require more thought, and certainly a pressure safety valve.

TTL and CMOS are on their way out due to the availability of inexpensive microcontrollers; not too far in the future I'm sure we will see the majority of those series be discontinued.

While Arduinos are attractive as proof-of-concept, breadboarding, and hobbyist uses in laboratory settings, the corrosiveness and physical shock potential of the intended environment would likely lead to rapid and continual failures.

Due to the desired longevity in a corrosive environment with significant physical shock possible, I'll suggest that the board will need to be conformal coated, connectors and wiring will need to be waterproof and at least automotive rated, and switches should be capacitive instead of electro-mechanical.

Also, while flash-based memory has a reasonably long retention life, mcu's with EPROMs should be used instead for the finished product. However, it would simplify development to use FLASH memory.

I have an assortment of Microchip PIC uC's at the house, along with Mikroelektronika C and a PIC6 dev board; I'm not at home now, but will try to make some progress on this over the next few days.

 

Have a look at a Propane bird scarer as used by farmers, they have all the valves and ignition systems and could probably do the job.

 

Have a look at a Propane bird scarer as used by farmers, they have all the valves and ignition systems and could probably do the job.

I suggested that in post#24. Even gave a link to Google that gave some circuits.