Hello ;

I'm looking to commission a project from someone. I do not know electronics and do not have the capability or tools. I am looking for a circuit to power some small dc motors for an art project.

Power 3 motors
turn on and of at random intervals.
speed at random patterens.


I am an artist , and would like to do this before Christmas. This will be for a train display. I can be reached via <SNIP> This would be a paid project.

Thanks Brian

I will check here for replys.
Below are the type of motors

 

You probably should remove your e-mail address from your post. Otherwise, bots will harvest it for the spammers.

 

Welcome to AAC.

Listen to WBahn, remove your e-mail ASAP, lest you get flooded with spam.

I think I can help.

I'd suggest discussing your project here so others might learn and contribute which will likely yield a better solution. If you decide to move forward and have me build it, we can work out payment for parts and labor through PM (private message).

To that end, I would suggest using a microcontroller. I can program it to output a PWM (pulse width modulation) signal to some MOSFET's which will cause the motors to vary in speed. Timing will also be handled by the microcontroller. Once the program is written, I can show you how to easily reprogram the chip to change the timing or speed variations in the future if you so choose.

If instead you want a purely hardware solution where you can change the speed and timing manually, it can be done, but it will require more parts, time, and cost.

If you would prefer to keep this private, simply send me a PM.

 

I don't think he can PM until he has 10 posts. You also can't PM him in the mean time. There's an option, when clicking his Username, to send an e-mail to him. I don't know if that is always active, or if he has to enable it in his profile.

 

Unfortunately i cannot remove my email address at this time.

elec_mech

If you decide to move forward and have me build it, we can work out payment for parts and labor through PM (private message).

To that end, I would suggest using a microcontroller. I can program it to output a PWM (pulse width modulation) signal to some MOSFET's which will cause the motors to vary in speed. Timing will also be handled by the microcontroller. Once the program is written, I can show you how to easily reprogram the chip to change the timing or speed variations in the future if you so choose.

If instead you want a purely hardware solution where you can change the speed and timing manually, it can be done, but it will require more parts, time, and cost.

It sounds like you can do this project.

I'm not sure what a micro controller is or how to program one.

I have worked with programming languages in the past.

I have tried to pm you, but the board seems to limit me at this time on what i can do.

 

No worries, we'll move forward here if that is okay, in this way others can offer their advice. You'll be up to ten posts in no time.

A microcontroller is an IC that you can program to do your bidding. There are a number of different manufacturers and programming languages. I'm planning to use the PICAXE as it is easy to learn and the software is free. My plan is to write the program and, depending on your needs, create variables at the top of the program you can change on the fly without needing to modify the code itself. So you'll be able to change things like top and bottom speeds, timing intervals, etc. If you feel ambitious down the road, you can learn the language (BASIC) and completely change the program if you so choose.

So I see one of the motors pictured appears to be a pager motor, is that correct? What are the other ones?

Are you planning to use three different types of motors (one of each pictured) or will you use three of the same motor?

Do you know what voltage each of the motors require?

How long would you like each motor on for, e.g., 1 second, 5 seconds, 2 minutes, etc.? Or do wish to the time to vary? If the latter, what is the longest and shortest times you'd like, e.g., 5 to 50 seconds?

How many different speeds do you want?

What is the top speed you want? If for instance, you connected the correct voltage to each motor and they spun full speed, would this be okay or do you need the top speed to be slower?

Do you want the motors to ramp up or down or just come on instantly to the desired speed?

Random is a little difficult, especially for microcontrollers, but there are some tricks we can employ. Is a repeatable pattern okay? We can have 5, 10, 20 sequences of different speeds and times for each motor, so to the casual observer the patterns will appear random.

Alternately, there are ways of looking at internal timers or external sensors to add an element of randomness to the program. The caveat is some patterns may repeat themselves back-to-back depending on the conditions.

Do you have a power supply in mind, e.g., plug in wall wart or batteries?

 

Are you planning to use three different types of motors (one of each pictured) or will you use three of the same motor?
The first motor on the left would be ideal.

Do you know what voltage each of the motors require?
I do not know anything about voltages i would need you to recommend, I just need the motor to vibrate (the buzz vibrate is what i'm looking for )

How long would you like each motor on for, e.g., 1 second, 5 seconds, 2 minutes, etc.? Or do wish to the time to vary? If the latter, what is the longest and shortest times you'd like, e.g., 5 to 50 seconds?

vary, 2 seconds to 5 miniutes

How many different speeds do you want?

3 or 4 different speeds would be great

What is the top speed you want? If for instance, you connected the correct voltage to each motor and they spun full speed, would this be okay or do you need the top speed to be slower?

full speed, just as long as the motors wont burn out

Do you want the motors to ramp up or down or just come on instantly to the desired speed?
both if possible or instantly at the desired speed

Random is a little difficult, especially for microcontrollers, but there are some tricks we can employ. Is a repeatable pattern okay? We can have 5, 10, 20 sequences of different speeds and times for each motor, so to the casual observer the patterns will appear random.

Perfect ! 20 sequences of different speeds and times for each motor, so to the casual observer the patterns will appear.

Do you have a power supply in mind, e.g., plug in wall wart or batteries?
Batteries

 

Excellent, I'll begin formulating a schematic and plan out the program.

The first motor you've shown is a pager motor which as you stated vibrates when it spins. So this is what you want?

Have you already purchased these? If so, can you post a link to where you bought them (or plan to buy them)? This will give me the information I need regarding the voltage.

If not, I have a one on-hand, so I'll use that to test with. Would you like me to supply the motors? If yes, how long do you need the wires between the circuit board and each of the three motors?

If memory serves, most of these use 1.5V, maybe 3VDC to operate. The PICAXE will require 5VDC, unless I luck out and find a 3.3V version, you'll probably need a 6VDC or larger battery pack (4x AA or AAA batteries).

Do you have any size constraints on the circuit itself? Tentatively, the circuit will probably be 2" x 2" roughly, possibly 3" x 3" or so. Is this okay?

Do you need an enclosure for the circuit board? Is it okay to have a simple power switch so the motors will run for as long as the switch is in the ON position?

Got plenty of info now to start, so no rush.

 

True random's hard to do but good enough pseudorandom isn't. This may already be in your bag of tricks; if not, here it is:

http://www.electro-tech-online.com/threads/need-simple-random-function.119179/

 

Excellent, I'll begin formulating a schematic and plan out the program.
Great

The first motor you've shown is a pager motor which as you stated vibrates when it spins. So this is what you want?
yes

Have you already purchased these? If so, can you post a link to where you bought them (or plan to buy them)? This will give me the information I need regarding the voltage.
no i have not purchased anything, I did see them at radio shack, i was told they are carried nationwide

If not, I have a one on-hand, so I'll use that to test with. Would you like me to supply the motors? If yes, how long do you need the wires between the circuit board and each of the three motors?

please supply the motors, if you can make the wires 3 ft long, it will allow me to wrap along branches. Can you make this with 4 motors ?

If memory serves, most of these use 1.5V, maybe 3VDC to operate. The PICAXE will require 5VDC, unless I luck out and find a 3.3V version, you'll probably need a 6VDC or larger battery pack (4x AA or AAA batteries).

thats OK,

Do you have any size constraints on the circuit itself? Tentatively, the circuit will probably be 2" x 2" roughly, possibly 3" x 3" or so. Is this okay?

What you need to make it is OK, I can hide it in the base of the project.

Do you need an enclosure for the circuit board? Is it okay to have a simple power switch so the motors will run for as long as the switch is in the ON position?

yes a simple on switch is OK. just keep in mind the randomness of "on" for each motor will have a 'rest' or 'off' beteen each 'on' cycle . I understand the on off switch is to power the project ?

Got plenty of info now to start, so no rush.

Thanks , do you have an idea of what this will cost ? you can email me or pm me. Thanks

 

If this works out well, I have a couple of other projects , involving lights if you are interested.

 

KJ6EAD - thank you for the link. I was not aware of that method, so I'll keep it in mind.

OP,

I can get those at RadioShack, but I found them on eBay for less than half the price. I'll get those on order now.

I'm still working out the method, but, yes, I can add another motor for a total of four.

I think you might be able to get away with two AA batteries, but I'm still in the design stage and moving - slowly - toward the experiment stage. I did a quick test with the one pager motor I have and it required ~125mA at 1.5V, ~250mA at 3V. This means with four running, the current draw could be 500-1000mA. On a set of brand name AA's, this gives you roughly 2.5 to 5 hours of runtime. If I can decrease the number of batteries to two, you could use some C or D batteries and get more time or use a wall wart (power supply that plugs into a wall outlet).

Yes, the ON switch is only for power to the whole circuit. Once flipped on, the circuit immediately starts up.

Another question comes to mind - do you have a desired off time between the on times for the same motor? In other words, if a motor runs for 20 seconds then stops, do you want it off for 20 seconds before starting again (for a different run time), or should the off time be somewhat random too?

Feel free to make multiple responses, say one response per question or comment so you can get the revered ten posts to allow you to PM. Sorry, I did not jot down your e-mail when it was posted originally.

 

Yes, the light projects would certainly be of interest. We can discuss those once we've gotten through this one.

 

I would like to stick with AA batteries, would 4 give it more then 5 hours ?

 

Another question comes to mind - do you have a desired off time between the on times for the same motor? In other words, if a motor runs for 20 seconds then stops, do you want it off for 20 seconds before starting again (for a different run time), or should the off time be somewhat random too?

yes the off time should be random

 

I would like to stick with AA batteries, would 4 give it more then 5 hours ?

If I can get away with 3V operation, then yes, you can put two sets two AA batteries in parallel, effectively giving you double the run time. The numbers I've give thus far are conservative, so it may run longer.

I just ordered the motors. They may use less power than the one I tested, meaning longer runtime, but I'll find out once I've got a circuit assembled.

 

im really excited to get this art project finished.

2 more post to 10

and i'm there !

 

Below is a first cut at the circuit and bill of materials (BOM). I did not factor in things like shipping costs of parts, solder, etc. - this is strictly meant to give an idea of basic parts cost for someone interested in pursuing a similar project in the future.

D5-D8 are used to lower the voltage going to the motors, since the motors are rated at 1.5VDC. As I understand it, one could potentially drive the motors at twice their rated voltage safely by not exceeding a 50% duty cycle. Hence, I may not use these I wanted to include them just in case.

The 74HC14 is used to invert the signal from the cheap USB-to-TTL converter in order to program the micro-controller - under $5 vs. $15-$20 for a dedicated programming cable.

The switch serves two purposes. One is to cut power to the circuit during normal use. Second is to prevent the USB-to-TTL converter from attempting to charge non-rechargeable batteries when connected to a computer.

To keep things simple and reduce time, my plan is to come up with 20 sequences for each of the four motors so they "appear" to go off randomly.

Final design including program will be posted once complete. This is being shared to a) save the OP money (no charge for design, only parts and assembly labor) and b) allow others to learn who may want to pursue something similar in the future.

Questions, comments, and suggestions are welcome.

 

Curiously absent from the BOM: vibe motors.

 

Curiously absent from the BOM: vibe motors.

Third item from the bottom - pager motors, M1-M4. Or am I missing something else?