Laser Spyro

[Kookapeli]

You've seen plenty of these here before, mines no different, so here's a sneaky peak before the main build !!!!

 

[ideas]

nice, but I think you could do a smaller fit for that, seems like a lot of unused space..
from my own exp: when it's finished you always regret making it to large and want to redo it smaller lol

 

[Kookapeli]

I'm just using realy small motors, it's roughly the size of a DVD case. I didn't want to go too small incase I had problems with the alignment etc, I'll probably sell this and make one a little smaller

 

[jimdt7]

I think it is hard to sell a Spyro because it is very easy to build !

 

[weeba2kv]

I hope those potmeters will last long nice build

Here is mine

 

[Kookapeli]

I was thinking of selling it to a non laser enthusiast

@ Weeba - looking good


Does anyone use on/off switches to stop individual motors or just use the PWM/Pots and is there a chance of burning anything out doing this ???

 

[Kookapeli]

I've got all the motors working but they spin like buggery, they run at 13000rpm
my pots are 500 ohm and need to get them down to 100 or 50 am i right in thinking if
i put a 400 ohm resistor somewhere on or before the pot that would work ??

 

[Pontiacg5]

How do you know those motors are turning at 13K rpm? That is obscenely high for those bearing-less motors.

Where did you get the motors? If you bought them somewhere like radioshack or digikey they should have voltage and current ratings with an RPM at those settings. If you have that info you can do a few simple calculations to figure out what size resistor and potentiometer you need.

The single standalone resistor should (probably) be smaller than the potentiometers maximum resistance, the thought being that the single resistor limits the motor to its rated V & I and the added resistance from the pot slows the motor down. If you pick too large of a resistor to add the motors won't be able to run as fast as they can. If you pick a pot that is too large you'll end up with 3/4 turns of motor off and 1/4 turn of slow to wide open.

If you just want to go about it blind...
Resistance added in series is cumulative, so to slow the motors down just keep adding more resistance to what you already have till you get speeds you like.

 

[Kookapeli]

The motor I have is the MTR2 motors

do I add the resistor before the pot or on the pot i.e between 2 of the 3 pins ? I tried to get smaller pots
but couldn't find anywhere that didn't charge less than $12 shipping to the UK I did want 100ohm but
no avail

cheers for the help

 

[Meatball]

You could try PWM. It can give you very precise control over motor speed. Does this circuit look like something you could construct? I can help you with component values and whatnot if you need...

 

[Kookapeli]

Maybe on my next project I'll opt for the PWM, but I'm going to stick with what I've got at the moment it's cost me enough already I just need to know do I need to stick the resistors across the 2 pins on the pot or before/after the pot ?

 

[Pontiacg5]

Not across the two pins of the pot, that would put the resistance in parallel. (I assume you mean a leg and the wiper right? You need to be using an inside and one of the two outside terminals of your pot.)

Either before or after the pot is fine, assuming you want to add the resistance in series. Search google for the difference and it should all make sense

 

[Kookapeli]

Cool, I'll give that a go on the w'kend and fingers crossed