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Phase Lock Indicator

I was watching a youtube video about a Nagra reel-to-reel deck and it had a neat little phase lock indication that I would like to duplicate. However, I want to make a stroboscope with an LED illuminating a small white disk with 5 black spokes on it. When the spokes appear stationary phase lock is achieved. The ratio is 5/2. I realize the ratio has to be a whole integer number for this phase indicator to work. This is easy as I can tap the part of my circuit that gives a 10:2 phase ratio and paint 5 spokes on the disks. I am confident it will work. I am just wondering if they make small ac sync motors that will run off of low voltage (i.e. 9V) AC. It would need almost no torque. It would just be turning a tiny white disk over a window in my project.

Thanks, Chris Maness

Reply to
Chris
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No, this indicates *frequency* lock. It was also commonly used on some turntables -- with multiple sets of "spokes" (your term) on the platter.

Presumably, you will be varying to adjust the speed of your motor to bring the "rotating disk" into frequency lock with the strobe? (or, are you varying the strobe rate to cause the disk to "appear" to stop -- it's unclear what your purpose here is) E.g., you might find it easier to use a small *DC* motor (e.g., out of a child's toy) and control the drive to that.

Reply to
D Yuniskis

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Well, adding the DC motor controller would double the complexity of the whole circuit. But looking around I did not find too many low voltage motors, and the ones I did find had reduction gears.

I will have to rethink this. My current design has an LED that lights up when lock is achieved, but I am not sure it will be dim enough when the frequency is not locked. I might have to set up some sort of threshold that only indicates when there is a steady lock. Here is my current design:

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Thanks, Chris Maness

Reply to
Chris

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I fixed it. I changed the time constant of the RC circuit that controls the inverters. The nor gate works off of pins 1 and 2 of CD4046.

Thanks, Chris Maness

Reply to
Chris

The jpg is hard to view. if you use a transformr you can drive a sync motor with less than 120 volts. A 12 volt secondary might work.

90 volts will drive a 120 volt motor.

greg

Reply to
GregS

Small stepper? Really tiny, like the old floppy stepper that shrunk to about 1/2 " diameter over the years. Speed control is open loop.

Image is too small for my tired eyes.

Grant.

Reply to
Grant

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Thanks, Grant. I fixed it. I just had to change the RC time constant to ignore all the little fluctuations until the loop locks.

Regards, Chris Maness

Reply to
Chris

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Man, that image is too tiny for Superman's eyes.

Reply to
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