When you put the cost of the pwm circuit and motor vs. a gearmotor, that makes that 555 pwm much more tempting, in fact I think i will do that, also, it will help the size constraints- I have to remember, this is a piggy bank. The purpose of all this will be defeated if the bank is all full of electronics and big gearmotors and there is no room for any money. Also, I updated the "power budget" it is now to the specs of the smaller but more powerful gearmotor, but will probably change, once I make the adjustable pwm. I am going to bed, and will let you know how things go. Thanks again for all of your time and help. Many of the schools that send students to the career center that I attend had no school due to snow, including the kid in electronics who is supposed to help me build the circuit, so hopefully tomorrow. Honestly, I should have looked into this sooner, but I really dont know how a smoke unit produces chuffing smoke in a model locomotive, whether it be by mechanical or electrical means. If it is by mechanical means, I am almost thinking of building a small diaphragm, such as those on a speaker, sealed to a chamber, used to pulse the smoke. It would be smaller than a motor and piston. A circuit would have to be designed to deliver a pulse of DC current to the coil of the diaphragm once per second. how hard would that be?
Sincerely,
Nicholas K. Heinrich

 

This is the inside and outside of the bank, with my hand next to it for size comparison.

 

A circuit would have to be designed to deliver a pulse of DC current to the coil of the diaphragm once per second. how hard would that be?

Astable multivibrator.

This is the inside and outside of the bank, with my hand next to it for size comparison.

Wow. That is going to be a challenge.

Patience. One step at a time.

 

I have found this solenoid, it is very compact, and I think it will be perfect to pulse the smoke, also the electronics teacher is putting me with a student who is very good at getting things to fit in small spaces, such as this entire circuit on a 1.5" X 2.5" circuit board. This is the link to the solenoid I found: http://www.adafruit.com/products/413

I will look up astable multivibrator, I wouldnt think it to be too complicated.
I looked up astable multivibrator, and found a 555 relaxation oscillator. here is a picture of three basic types. Would it be possible to make one that has an adjustable Hz range. I need about 1-3 Hz.

 

Can you build a base to mount the bank upon, which could then be used to house the electronics?

 

Wow, just wow, I cant believe I didnt think of that! Thank you so much djsfantasi! You just made my life so much easier!