Moving Head Spotlight

Guest,

While you could get away with two DPST switches, there ARE DPDT micro-switches available on the market.

Honeywell has at least a dozen models, which should be available through the larger electronic parts distributors.

(Try www.newark.com for starters)

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Just my $0.02

Sounds like a windshield wiper motor/gearbox to me...

Marine spotlights offer vertical and horizontal movement via a joystick type controller. Most of them are quite small for their power and are not that expensive. Why not Google "Marine Spotlight" and see what you get? OR, do you want it to sweep back and forth continously? If so, I'd go with the windshield wiper concept posted previously.

There are worm gears and shafts available from Northwest Shortline that could work this problem. Is the motion to be continuous or interrupted? In either case, a simple design where the worm gear is on a shaft that extends out of a block of sufficient thickness to provide adequate bearing to hold the shaft from sidewise motion and a shouldered screw threaded into the worm gear with a link to an arm on the spotlight's pivoting mount should do the job.

If you want a reliable design, do it without switches. Instead use hardware and software to sense the motor current increase when running into a "crash stop". It involves a bit more design work, but will pay back in the end due to the much improved reliability of the end product.

Even using the best switches around, you will need a second emergency stop switch in case the first stopped working!!

End stops can be spring loaded if required to increase load current without locking up...

As you have not given us much detail to work with, I cannot be more precise than that....

If there is a computer near by i would suggest a stepper motor and a simple program in Visual Basic. all parameters are programable-speed, Dwell, cycle time,ramp up and down, etc.

CCTV Camera mounts.

Good luck,

James

I've done this with a stepper for a rotating robot sensor array. You need to consider the spotlight weight (affects size of motor) and type of motor. You have a couple options:

1. simple direct control of motor that reverses when hit limit switch on either side -- the switch will have to take the motor current or be a simple micro SPST that then controls relays.

2. have a small CPU control or digital logic drive a motor controller (again, depends on the size of motor) -- the suggestion above for a stepper motor works well here, but a DC geardrive will also work -- again a simple SPST microswitch is all that is required for the limit sensor

Things to watch out for:

1. The motor will not stop immediately, so you will have to allow some time to turn direction.

2. Depending on how you drive the motor, you will want to be careful NOT to immediately reverse power to the motor to increase its life.

Other items:

motor drive supplier http://www.pololu.com/products/elec.html#motocon

remote search light: http://www.premiermotoring.net/cgi-bin/webc.cgi/st_main.html?p_catid=1350

Hi Joe,

You have received a lot of good feedback to the problem of a 90 degrees moving arm. From your question, an answer comes to mind: use a single SPST limit switch. This could supply the coil of a more complex relay that can perform all your requirements.

Keep it simple... How about a crank attached to the motor shaft, and a lever arm with the proper pivot to get the necessary motion. mount the spot light so that it can piviot and have a lever arm with a slot to attach to the first lever.

It is hard to discribe... wish I could supply a picture...

Play with the concept and the geometery.....

Control the motor speed to your need and the spot light will sweep back and forth... No switches no computer no software....

Keep it simple... Hope that will satisfy your needs

Reminds me of the rice farmer who had trouble with air borne eagles. He wired a weapon to a flywheel. One automotive starter on each side, oscillated them through limit switches. Leveled his weapon, run his wire back, and waited......................

...similar to windscreen wipers?

# 10 has your simplest answer..trouble free....constant single rotation motor.....no computer needed...no intermitnt reversing switch needed........just a #1 drive small #1 cam with a travel rotational/linear throw of 25% of the throw on an connecting link arm driven slave cam holding light fixture on #2 cam's center axis.

Cheap..only four bearings beyond the drive motor mounted #1 cam....subject only to the mass of the light fixture and desired frequency/speed of display of said light.

MR.GUY

This is exactly the same approach that I mentioned before. Use a worm and worm gear to reduce the speed at which the light changes direction. A crank directly on the motor shaft would likely make the light reverse much too rapidly. My approach would delete the need for a separate crank and use the shouldered screw as a crank.