Coin Mechanism

Thread Starter

Nicholas K. Heinrich

Joined Feb 25, 2012
102
Haha, maybe, but im not just a newbie to this, but have avoided all things like this as much as possible for a long time, so im even worse. The steam locomotive I volunteer on is a far cry from any of this.
 

Pencil

Joined Dec 8, 2009
272
Ok, I will, thanks
I have reviewed the source you provided, and understood about half the words. I am not yet able to read cicuit schematics, so this is vey confusing.
Plenty of help here, don't worry.

I am gathering that timing duration is based on the capacitors value?
The timing is based on the value of the capacitor and the resistor.
The formula is: Seconds=1.1 x R x C. What range of times (in seconds)
were you thinking for the output?

I (or someone else) will probably work up a schematic in a day or so.
 

Thread Starter

Nicholas K. Heinrich

Joined Feb 25, 2012
102
Thank you, my goal was either a 30 or 45 second duration, based on my lionel model locomtive's smoke unit, which takes about 20-25 seconds to heat up.
 
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Thread Starter

Nicholas K. Heinrich

Joined Feb 25, 2012
102
Thanks, that's good, I was hoping to eventually make it adjustable, after I get it to work at all of course. I am going to bed, but tahnk you for all the help so far!
 

Pencil

Joined Dec 8, 2009
272
Attached is a preliminary schematic.

See if this is something you might want
to tackle. It is not as intimidating as it
might seem.

A few component values will need adjusted
as the final parts are chosen.

The two (2) 555 timers could be replaced with a
single 556 in the final build.
 

Attachments

Thread Starter

Nicholas K. Heinrich

Joined Feb 25, 2012
102
Thank you, This would be something I may be willing to tackle, but I think I will print it off, and have the elctronics teacher help me to understand it a little better. Im just ahppy I actulally know what you are talking about with the 555 v. 556 timers. A 556 is simply two 555s stuck together, yes? I believe they share incoming power pins or something like that. I am going to bed, I will try to get on tomorrow. Thanks for all the help by the way, I hope that someday I can contribute to this board as well. :)
 
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Pencil

Joined Dec 8, 2009
272
Im just ahppy I actulally know what you are talking about with the 555 v. 556 timers. A 556 is simply two 555s stuck together, yes? I believe they share incoming power pins or something like that. :)
Basically, yes.

Good luck. Post questions as needed.

As stated earlier, some component values may
need changed in the final build as the final
selections are made.
 

Thread Starter

Nicholas K. Heinrich

Joined Feb 25, 2012
102
What do you think the relay's capacity should be, im thinking around the capacity of the power supply, about 12v/ 600 milliamps. And, since you are a machinist pencil, what would be more practical / economical, a small 12v motor linked to a series of brass reduction gears or a 12v motor supplied with 1.5 volts so it goes really slow. I supplied a 2300 rpm 24 volt motor with 3 volts, and it went at the right speed. So I figure if I can find a small 12 volt 2300rpm motor and supply it with 1.5 volts, it should do the same thing right? BTW i plan to use about 6 3.3 volt zeners in parallel and some resisitors to reduce the 12 volt output for the light and smoke unit to 3.3volts for the motor. I have been unable to find a 1.5 volt zener, so I went a little higher than reccomended on the resistor. It said 10 ohms, so I will go with 15, and hope it drops the voltage a little closer to 1.5. The motor will drive a small crank and piston hooked to the smoke unit with a tube to reproduce the pulsing or chuffing of the smoke. I went to the elctronics teacher and he said he would have one of his students set down with me and build the circuit, at no cost to me! I hope to add this on to the circuit for the motor. The smoke unit will consume 120milliamps, and the light should consume about 25 milliamps, I dont know how much the circuit will use, but I think the motor is the biggest power variable of all.
zener-diode-voltage-regulator.PNG
 
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Pencil

Joined Dec 8, 2009
272
What do you think the relay's capacity should be, im thinking around the capacity of the power supply, about 12v/ 600 milliamps.........The smoke unit will consume 120milliamps, and the light should consume about 25 milliamps, I dont know how much the circuit will use, but I think the motor is the biggest power variable of all.
Best bet for sizing relay is to consider maximum expected load and
add 50% more (x1.5), or double (x2) capacity. Other factors to
consider are physical size of the relay and current requirements
of the coil. A relay is a "power hog", but also the easiest way
to switch an unknown or varying load.

And, since you are a machinist pencil, what would be more practical / economical, a small 12v motor linked to a series of brass reduction gears or a 12v motor supplied with 1.5 volts so it goes really slow. I supplied a 2300 rpm 24 volt motor with 3 volts, and it went at the right speed. So I figure if I can find a small 12 volt 2300rpm motor and supply it with 1.5 volts, it should do the same thing right?
Supplying motor with excessively low voltage to reduce speed is
generally a bad idea. Look into "Pulse Width Modulation" or "PWM".
This could possibly solve your problem without wasting power and
generating unwanted heat. This could be another 555 timer project.
A gearbox/geartrain is probably unnecessary. It would add bulk and
complexity where it is unneeded. The advantage would be an increase
in torque/power, which probably isn't needed.

BTW i plan to use about 6 3.3 volt zeners in parallel and some resisitors to reduce the 12 volt output for the light and smoke unit to 3.3volts for the motor. I have been unable to find a 1.5 volt zener, so I went a little higher than reccomended on the resistor. It said 10 ohms, so I will go with 15, and hope it drops the voltage a little closer to 1.5.
See above note about wasting power.

I went to the elctronics teacher and he said he would have one of his students set down with me and build the circuit, at no cost to me! I hope to add this on to the circuit for the motor.
This sounds like an excellent situation. Remember, one step/component
at a time. Get each piece to work individually then integrate the
parts for a complete working system.


FYI: I built the circuit myself on a solderless breadboard and it does
function as expected.
 
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Thread Starter

Nicholas K. Heinrich

Joined Feb 25, 2012
102
Thank you, and I dont much care if somehting is a power hog, I'm not looking to conserve electricity here, although excess heat is somewhat of a consideration, and I will definately look up pwm. I looked up pwm, and how would I calculate how many Hz to pulse it at to get 250 rpm? This is a good website for dc motor speed control. I dont understand that much of it but maybe you can. http://www.robotroom.com/PWM.html
 
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Pencil

Joined Dec 8, 2009
272
and I dont much care if somehting is a power hog, I'm not looking to conserve electricity here, although excess heat is somewhat of a consideration,
Not only is being efficient the responsible way to design, but it also
goes directly toward the lifespan and reliability of the device.

I was not trying to steer you away from the usage of the relay,
merely stating a fact.
 

Thread Starter

Nicholas K. Heinrich

Joined Feb 25, 2012
102
that is a good point. But for something I'm spending quite a bit of money on, reliablity and lifespan are huge considerations, although a relay being the simplest way, that is the way im going to go.
 

Pencil

Joined Dec 8, 2009
272
I looked up pwm, and how would I calculate how many Hz to pulse it at to get 250 rpm? This is a good website for dc motor speed control. I dont understand that much of it but maybe you can. http://www.robotroom.com/PWM.html
You need to experiment with your motor. Read about the ideal
frequencies. Build an adjustable unit operating at the desired
frequency. Perform tests. Vary frequency and duty cycle until
a desirable result is found.
 

Thread Starter

Nicholas K. Heinrich

Joined Feb 25, 2012
102
Ok, so should I build a circuit like the one on the link provided, get a motor, and hook it up and play around with it? Also, what are the chances of finding a 25orpm motor?
 

Pencil

Joined Dec 8, 2009
272
Ok, so should I build a circuit like the one on the link provided, get a motor, and hook it up and play around with it? Also, what are the chances of finding a 25orpm motor?
Look for 555 PWM. I mention the 555 because it is cheap,
readily available and there is tons of examples/circuits/information
available. Also when you blow one up at a critical time a replacement
is usually available locally.

250 RPM motor? Not gonna happen. Figure out how to use what is available.
 

Thread Starter

Nicholas K. Heinrich

Joined Feb 25, 2012
102
Ok, I think I will, but more just for kicks, because I just found a 120rpm 12vdc 150mA gearmotor, it is small and will fit perfectly, aslo it is only about $15, and is closer to the speed I was looking for anyways. Or would that produce too much heat? The running total is 295mA plus whatever the cicuit itself(including what the relay uses.) Also, is this a good 555 pwm cicuit? http://www.dprg.org/tutorials/2005-11a/index.html
 
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Pencil

Joined Dec 8, 2009
272
Ok, I think I will, but more just for kicks, because I just found a 120rpm 12vdc 38mA gearmotor, it is small and will fit perfectly, aslo it is only about $13, and is closer to the speed I was looking for anyways. Or wuld that produce too much heat.
Ahh gearmotors, that is a whole different ball of wax. The motor runs
at its rated speed and the attached gearbox does the reduction. This
is a relatively good way to reduce speed and retain power, but the tradeoff
is the relatively high price compared to an ≈$3 motor and ≈$2 in components.
Build it and see.

the running total is 183mA plus whatever the cicuit itself(including what the relay uses.)
It is good that you are tracking your power budget.
 
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