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View Full Version : dissected vcr...lotsa parts



dr0w
11-10-2005, 08:45 AM
hi,
i opened some old malfunctioning vcr laying in my house and got a ton of nice mechanical parts, sheet metal for casings, two dozens of microswitches, and many other things to lay around in future and piss my girlfriend.
one particulary interesting part was the brushless motor which is actually called "video head motor".
after i RTFM-ed for a while i found out that it is (brushless DC motor) controlled via 3 coils, much like a stepper motor, i guess it is fed with 12v nominally.
problem is that it has a shitload of pins to connect to, i found some 14 in a single plastic header connector, which made motor twitch after i pressed random pins with a 9v battery, still hadn't found much logic in it, it is late and im anxious, so i fear to shit something up, so i'll leave it for tommorow.

did anyone interfaced it in past? which IC should i use to control it? some stepper controller or a specialized ones? i need some form of digital control since i plan on connecting that to a microcontroller.
thanx

quasar
11-10-2005, 08:24 PM
If i am correct.... What you are having right now is a sensored 3 phase DC motor with Hall outuput...

first of all.. I dont have a first hand experince in this....

any way....

http://www.designnotes.com/CIRCUITS/dcmotor.gif

This circuit can directly drive your motor..The Speed can be controlled by selecting different crystal values....

".........The motor cannot commutate the windings (switch the current flow), so the control circuit and software must control the current flow correctly to keep the motor turning smoothly. a simple half-bridge on each of the three motor windings can do the job.There are two basic types of Brushless DC motors sensor and sensorless. Because it is critical to know the position of the motor so the correct winding can be energized, some method of detecting the motor position is required. A sensor
motor will directly report to the controller, the current position of the motor. Driving a sensor motor requires a look-up table. The current sensor position directly correlates to a commutation pattern for the bridge circuits...."

Took from of the App notes in Microchip....google it.. i got it from the CD..

have a look in one of the manafactures appnote.......

http://www.beikimco.com/appguides/motors.php

ok

Quasar...

dr0w
11-12-2005, 07:47 AM
thanx,
i found that app note, as well as for atmel (my target uC), it has sources and everything.
but since i only worked with regular DC's i think this is overcomplicated to start with. ill go trashing tommorow to the flea-market to find some old 5.25" floppy's stepper and try that for starts.