Animated Reindeer motors and LE's

[GrumpkaXmas]

My apologies if this subject has been covered prior. 

Has anyone used a Lynx Express to control animated reindeer motors?  Here are the specs; (similar to that of the deer motor, might be a little off... close as I could find)

1)         Rated Voltage: AC  110V
2)         Rated Frequency:50/60 Hz
3)         Rated Power Consumption:3.5 ± 0.5 Watts
4)         Current Consumption:30 ± 5 mA
5)         Withstand Voltage:1500 VAC / 1Min
6)         Insulation Resistance:Over 100 MΩ at 500 VDC
7)         Insulation Class E

I must admit, I did try to run a very small AC fan on an LE with success.   No heat off the triacs or heat sink.  No issues with fan.  NOT saying you should do this, as I did it as a bench test only!   

I'm just curious if the Triac's can/should handle a very low amp draw like this.  The load type is different than a bulb, but still want to know IF it could work, and would it harm the LE's?

The application idea is a traditional animated prop with several deer motors in place of servo's.   Example, might have a santa with a waving arm on one channel, head turning on another, and even a third for eyes and or mouth.   Seeing as it would be seeking that 'warm' old school animation effect from years past, not looking for precision of modern servo driven props...

Thoughts?  Warnings?  Stop here, do not pass go?

[tomwb301]

What I would do is let the triac operate an 8 or 11 pin ice cube relay that has a 120 volt coil. The current load of the coil of the relay is very low. Then let the relay drive the motor load. Motors, how ever small, have an inrush load and might damage the triac.

[GrumpkaXmas]

That's a thought.  Based on the triac specs, an inductive load of a small AC motor shouldn't be an issue.  I guess I'll have to do some bench testing and watch what kind of loads come up with the motor.   Also, thinking a 'fade in' instead of an instant full on might address the startup load stress concerns.  No expert, so might be the wrong avenue to even consider.   Checking into the relay option in the meanwhile.

Thanks for the help.

[RJ]

That's a thought.  Based on the triac specs, an inductive load of a small AC motor shouldn't be an issue.  I guess I'll have to do some bench testing and watch what kind of loads come up with the motor.   Also, thinking a 'fade in' instead of an instant full on might address the startup load stress concerns.  No expert, so might be the wrong avenue to even consider.   Checking into the relay option in the meanwhile.

Thanks for the help.

This is a thought of a way around the inductive load issues. but you need a fade out also as one of the biggest issues using the express to run will be that when you turn it off the magnetic field in the coil of the motor can produce a very high voltage exceeding the triac rating. this is how old cars ignition coil produces the spark for the plugs they power a coil of wire and turn it off. the field falling quickly generates a low current very high voltage spike we use across the spark plug. But if you ramp the voltage down slowly this might not be an issue as you would be limiting the speed the field was collapsing. But if you add a diode acorss the motor feed with it allowing backwards current flow you can overcome this also if it is a fast diode. 

RJ

[tbone321]

You really can't just say an inductive load because motors are in a different world.  There are many different types of AC motors and they have different properties from standard inductors like a straight coil.  There are many types of motors that run on AC and each type has has different properties and since they have moving components withinthe magnetic field, the properties and level of inductance changes with the speed of the motor. 

I guess that what comes first is your intention for using the controller on the motor(s).  If you want to control their speed, remember that many of the AC motor types will not respond to or work well with a dimmer type control and some can actually be damaged by them.  Inductive loads (especially motors) also work best with smooth signals and if you look at the output of a triac, it is far from that.  Even at full on, a Triac does NOT provide equal output on both sides of the AC signal and while not much of an issue for lights, can be for motors and other inductive loads. 

The output from the motor even while running can cause issues with the triac as well.  Triac's cut off when the the current across them goes to zero and the kickback from the running motor can fool the triac and cause them to shutdown at the wrong time and possibly miss entire cycles from switching back on.  If you look on most dimmers, they clearly say FOR RESISTIVE LOADS ONLY and these are some of the reasons.

If all you want to do is turn them on and off, then I would go with the relay option.  Even though relays are also an inductive load, they are a straight coil load and the issues in this case can be properly controlled.  Since there is no need, capability, or reason to dim them, you can set the curve on the LE to ON/OFF only.  To deal with any kickback, you can put either a 47K resistor or a small bulb (C7 or C9) across the coil to dissipate any kickback.  You can't use a diode here because we are working with AC. 

[GrumpkaXmas]

Thanks guys.  In summary, or rather, layman's terms,  it's not such a great idea, although it would certainly work.  However, the triac is at risk, and perhaps even the motor.    End result could be magic smoke?