Wiring Diagram for Ultrasound 2.0 LED Saber w/Resonator

[clublimbo]

I've been lurking on the boards for a few months now and owe a lot to all of you for all of your help. I have built my first saber and am eagerly awaiting the arrival of my UltraSound 2.0 board. I've come up with a proposed wiring diagram (attached) that I would like to get some feedback on.

I'm using all TCSS parts with the exception of the Micro-Vibration motor (Radio Shack part #273-107) and the resistor. My end goal is to have the vibration driven by the board and tied in to the led pulses (not just on power up/down and clash/lockup).

Beyond my basic wiring design I also have questions re: choosing the right resistor for the micro-vibration motor. I found a really helpful thread where xwingband explains the formula for choosing a resistor (voltage drop/amperage). The motor uses 3V, so with 6V going into the board and a target amperage of 30 mA, my calculation indicates that I'd be going with a 100 Ohm/.09 W resistor. I'm planning to use Radio Shack part #271-1311 (a 100 Ohm/.25 W resistor) for this purpose. The thing I'm not sure about is how much voltage will be going to the motor. If I'm sending 6V to the board, then is 6V coming out? If not, that will change the amount of voltage drop and I'll need to recalculate.

Thanks in advance for your help and thank you all for the volumes of information that I've already found on these boards, it has been invaluable!

[MoonDragn]

well your source is 6V, your motor takes 3V and 30mA or .030 A. that means the voltage drop over the resistor has to be 3V with a current of .030A. R=V/I Which you correctly figured out to be 100 ohms. This will supply 3V to the motor but the other 3V is expanded through the resistor as heat.

I would measure across the output of the sound board to see the actual voltage coming out. Since it is a driver circuit, the voltage may not be exactly 6V.

also, put a small ceramic .1 uf capacitor between the casing of the motor to the leads. One to each lead. Otherwise your lightsaber will cause some radio interference.

[clublimbo]

Thanks, MoonDragn! I've updated my wiring schematic (below) for anyone else who is following along.

[xwingband]

Why does radio interference matter? Who gives a flip?

The setup is correct though. The voltage is not... You'll need to use the LED's voltage not your overall battery voltage. The board is regulating the voltage for the LED so it will spit out whatever the LED wants. You'll either have to measure it with a variable current supply or rely on the "normal" specs and over resistor. I over resistor motors anyway. I find that you want to give it just enough power to spin, otherwise it's hard to tell the variable speed and it feels like you're holding an electric razor. A small adjustable pot if you could get one would be great, otherwise I'd say shoot for 10mA-20mA.

[MoonDragn]

Why does radio interference matter? Who gives a flip?

The setup is correct though. The voltage is not... You'll need to use the LED's voltage not your overall battery voltage. The board is regulating the voltage for the LED so it will spit out whatever the LED wants. You'll either have to measure it with a variable current supply or rely on the "normal" specs and over resistor. I over resistor motors anyway. I find that you want to give it just enough power to spin, otherwise it's hard to tell the variable speed and it feels like you're holding an electric razor. A small adjustable pot if you could get one would be great, otherwise I'd say shoot for 10mA-20mA.

The Neighbors may call the FCC ;)

Seriously, it will interfere with your TV. It doesn't really matter unless somebody in your house was trying to watch tv.

I suppose 6V battery isn't really strong enough to cause that much interference, but its just a standard practice among hobbyists who use electric motors.

btw, I tested a motor similar to that one with 6V directly and it worked just fine so it can take more current than necessary, but like X-wing says, over-resistor it so it won't take more current than necessary from your LED.

[xwingband]

I've been close to my TV before with a motor. No problems. It's extra wiring that hardly offers any benefits. It would actually change the way the motor fades in and out.

[MoonDragn]

The motor fading in and out isn't good for the motor. It wears out the contacts and eventually the motor. Thats what the caps are there for, to smooth out the voltage fluxuations.

[xwingband]

I've yet to hear of anyone burning out a motor that way in the years I've been in this hobby.

[MaverickJsmith]

Motors are very resilient things by design. It won't hurt the motor, and any possible emmission intereference the electronics may put out is shielded by the fact the electronics are inside a metal tube. Besides, I doubt they'd readiate more than half an inch anyway. Hell, .1 inches.

Maverick 8)