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Need to Slow Down a Display Motor

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drabain

New Member
I have a DC motor that runs off a 1.5v D-sized battery. It is a motor that is inserted into a tube and has a connection peice that allows for 3 posters to be attached and they spin when the motor is turned on. The motor turns too quickly to allow for the info to be read. How can I slow it down or (even better) fix it up to spin a 1/3rd of a turn, stop for a about 30 seconds than turn another 1/3rd and stop for a about 30 seconds, etc?

Thanks
 

Mikebits

Well-Known Member
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drabain

New Member
Yes...either slow it down or have it spin in 1/3rd revolutions and stop for about 20 seconds. At the current speed, it spins too fast to propoerly read the display.
 

dknguyen

Well-Known Member
Most Helpful Member
The standard solution is to gear it down so the output of the gearbox rotates once for every 3 turns of the motor. Increases torque, lowers speed, and decreases motor current and heat.

Or you could feed it 1/3 the voltage or PWM it at the current voltage but with a 30% duty cycle. BOth of these methods however, decrease speed and decrease torque (possibly to the point where it is too weak).
 
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Sceadwian

Banned
How many batteries does it run off of?
 

drabain

New Member
Really don't have time or resources over here in Bermuda to build a gear solution. I would really like a "out the box" solution if possible that I can order and stick between the battery and motor. Motor is already geared, etc and is in a sealed plastic housing. It is really not possible to add gears to this solution (will post a pic later) and I need this about 2 weeks.
 

Sceadwian

Banned
Try putting a diode rated for constant current at 1.5 or 2X the motor's peak draw inline with the battery. That's a quick and dirty way to blow off a little power. Add more diodes, you'll get a slower motor, keep in mind this power is lost as heat in the diode itself depending on the current, so plan accordingly.
 

crutschow

Well-Known Member
Most Helpful Member
You could use a couple 555 timers to have the motor run for a given time and then stop for a given time. The first 555 would be connected as an astable multivibrator with a period of 20-30 (plus the period of the second 555) seconds. This would trigger the second 555 connected as a monostable multivibrator (one-shot) with a period sufficient to run the motor for 1/3 turn. The monostable will need a transistor amp to power the motor.

You can Google "555 timer circuits" for many references on how to design the circuits.
 

KMoffett

Well-Known Member
Just throwing together a concept. A 555 astable and three limit switches to stop the motor at the three positions and restart it after a delay. Sort of reminiscent of the windshield wiper delay circuits. ;)

Ken
 

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Sceadwian

Banned
Try the diode first =) Can't beat a penny part you just stick in vs trying a couple timer circuits you may or may not be familiar with.
 

Mickster

Well-Known Member
Most Helpful Member
Try the diode first =) Can't beat a penny part you just stick in vs trying a couple timer circuits you may or may not be familiar with.
As Sceadwian says, try the diode first. Pop into the electronics store on the corner of Church St & Washington Lane and ask for 1N914, 1N4148 or something from the 1N400X series, they should have them. You could also have a chat with the tech (older guy about 5' 6") he was always helpful when I spoke to him in the past.

HTH.
 

KMoffett

Well-Known Member
If the motor is running off of a D-cell, a 1N914 or 1N4148 might be a little too light on the absolute maximum If. Espacially for the motor start-current. The 1N400x would be a whole lot safer.

ken
 

drabain

New Member
Mickster - That store you refer to is Radio Shack and it closed about 3 or 4 years ago! LOL! Hence my need to do soemthign quick and dirty becuse I need to order the parts to come to Bermuda. The cleaner and less hassle it it, the better.....
 

Mickster

Well-Known Member
Most Helpful Member
drabain....PM sent.

EDIT: PM only contains contact info of others, not project solutions.
 
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