Motor Recommendation

[Jeremy S]

So I have constructed a mechanical TV using a disk from Peter Yanczer. It works to some extent, but I am having trouble keeping it in perfect sync. My disk is mounted to a hub made fro an old VCR head, and is driven by a belt.

I am using a old DC brushed motor from an 8track player. Peter suggested that this motor may not be the best, and said to maybe look for an AC synchronous motor around the 900 or 1200 RPM range.

See attached for my project so far. What are some good motors to consider using? I am using the PLL circuit available from the club handbook.

Thanks!

Jeremy

[Harry Dalek]

So I have constructed a mechanical TV using a disk from Peter Yanczer. It works to some extent, but I am having trouble keeping it in perfect sync. My disk is mounted to a hub made fro an old VCR head, and is driven by a belt.

I am using a old DC brushed motor from an 8track player. Peter suggested that this motor may not be the best, and said to maybe look for an AC synchronous motor around the 900 or 1200 RPM range.

See attached for my project so far. What are some good motors to consider using? I am using the PLL circuit available from the club handbook.

Thanks!

Jeremy

Hi Jeremy

i am no expert on this problem but i rather like Brushless DC motors but
it could be your belt drive ...i tend to use direct drive to do these things and i am in fact doing this my self for the current project so expect the belt if theres any slipping jerking what ever would cause speed changes.

But anyway i do think direct drive is easier if you can attach the disc to it ,
I have been looking into using PC Fan Motors they are Brushless and the big 12v ones look like they could be used .
Using a VCR head is good i like to use old Hard drives as i can attach the disc as it was a platter.....
I have not got these to work right but you could use the motor on the hard drive as well they will have the right speed for sure ....
Anyone got a good hard drive motor driver circuit ...

[gary]

Just my 2 cents worth:

The 8 track motor *should* be fine, I have been keeping one aside myself for just such an application. I can only assume that Peter thinks the motor may be faulty, i.e. brush wear, bearing failure etc.

His suggestion of an AC synchronous motor is fine, but if you use one you won't need to use the club circuit because it will be "sync-ed" to the mains supply. In fact you can't use the circuit as it is intended to be used with a DC motor. Unfortunately, AC synchronous motors are generally hard to find and tend to be very expensive when you do (unless you use a bicycle dynamo or stepper motor - both with their own "nuances").

There are many members who have used this disk with cassette motors with success, one on this forum that springs to mind is Andrew, the site "owner". His "construction Diary" http://www.taswegian.com/NBTV/forum/vie ... ry&start=0
should give you many suggestions of how to "debug" your system.

Keep in mind that it is not unusual to have problems "tuning" this circuit with your motor/disk/drive arrangement. Unfortunately it is not a "plug and play" type circuit as all the components disk, motor, bearing, belt, play a part in it's performance. Keep at it and I am sure you will get it working.