Photoelectric Switch controlling a 12V DC Motor.

Donald · Feb 3, 2013

I have a Photoelectric Switch controlling a 12V DC Motor. A 12V battery serves as the only power source. When connected the motor just makes a clicking sound. I tried smaller motors that worked. For some reason they now also just make a clicking sound and do not work.

Any reccomenddations are greatly appreciated. thank you.

Don-

Harald Kapp · Feb 3, 2013

What's that photoelectric switch? An off the shelf part or a selfmade contraption?
What's the rating of the switch and the ratings of the motors used?
Can you measure voltages and currents at the inputs and outputs?

duke37 · Feb 3, 2013

If the battery voltage collapses when on load, the relay will drop out and the battery voltage will recover, the relay will energise again and so on.

Make sure the battery is charged and in good condition.

Donald · Feb 23, 2013

Thanks so much for the quick response. Sorry for the delay. Family and travel issues popped up. And I can only work on this when the wife is asleep at night ;o)

Here’s what I’m working with:

Dayton DC Motor
12 Volt PM DC
HP. 1/35 RPM: 2350
FL AMPS: 3.70

Keyence Photoelectric switch. PR-MF Series
Power voltage: 10 to 30 VDC, including 10% ripple (P-P)
Control output: NPN or PNP Open controller, 30 V or less. 50 mA or less

A multimeter reading from the wires (brown & blue) from the photoelectric switch to the motor indicates 2-3 amps and upwards of 10-12 volts as I’m using a volt regulator to supply power. I’m experiencing the same results when connected to a 12 V battery.

I’ve tried smaller motors to trouble shoot. They began to work with the photoelectric sensor then all stopped working and emitted the same clicking noise. Feels like back EMF or something mucking up the works. I have tried an ice cube relay (not sure if I connected it properly and will try again). Would inserting a capacitor resolve? Any input is greatly appreciated?

john monks · Feb 23, 2013

What if you try with a small 12 volt light bulb?
Maybe there's something Strange going on in your Keyence switch.

Donald · Feb 23, 2013

I thought the same and purchased another switch. I'm on my third and the issue is consistant

john monks · Feb 23, 2013

What I meant was that there may be an SCR or other type of transistor circuit incorporated in the switch that might have current limiting. I'm trying to find the specifications on the switch. What happens when you bypass the switch? Do you have a voltmeter? Can you see what the voltage drop across the switch when the motor is making the clicking sound?

Donald · Feb 23, 2013

I see. Good point. I'll test that out to see confirm. Would the ice cube relay get around that?

duke37 · Feb 23, 2013

What battery are you using?
Is it fully charged?
Have you measured the voltage on load?

If it worked for a while, then stopped, it appears the battery ran out of breath!

What is an ice cube relay?
What is the voltage rating of the coil and its resistance or current consumption at 12V.

EinarA · Feb 25, 2013

In post #4 the specs Donald gives list the max control current as 50 mA and the motor draws 2-3 amps. You need a relay or a power transistor to drive the motor.

Photoelectric Switch controlling a 12V DC Motor.

Donald

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