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The CYBOT Motor Control Board

HOW IT WORKSPROBLEMSDOWNLOAD


HOW IT WORKS

This section is currently under construction

When the motor is operated in 'FAST' modes, the power is switched constantly to the motor.

For the 'SLOW' modes, the power is switched 50% of the time, on for 12.5ms, off for 12.5ms

Connections

PINFUNCTION
1Right Motor - FORWARD
2Right Motor - REVERSE
3Left Motor - FORWARD
4Left Motor - REVERSE
5+5v Output
6+6v Output
70v Output

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PROBLEMS

A number of problems could exist:

1. Potential Short Circuit
By driving the H-bridge with an on - on signal, all devices in the H-bridge will be enabled.
This will have the effect of shorting the 6v power supply.
The overall result would be several damaged transistors and if you're unlucky - smoke.

Cure:
1. don't drive the H-bridge in that way
2. apply some form of over-current protection
3. use an alternative motor driver

2. Poor Design
Polarised capacitors are placed across the motor outputs.
This is fine for forward motion, not so good in the reverse motion.
Generally the life of the component may be dramatically shortened by such use.
The result could be a shorted circuit capacitor, physical leakage or in the extreme rupture or explosion of the capacitor.

A possible thought was that the motor may only ever run in a forward motion.
It has been seens that at issue 13, the motors operate in both directions

Cure:
1. remove the capacitors, local suppression capacitors are fitted to the motors.
    ( motor operation may sound more noisy )
2. replace them with non-polarised capcitors, i've done this.
    ( Before and after pictures are available in the
Download area of this page )
3. ensure that the motor is always going forward, if you use an alternative control system.



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DOWNLOAD AREA

Motor Board Schematic
gif
pdf
zipped pdf


Datasheets
2SA1300
2SC3279
S8050 Datasheet

Motor board before capacitor change
Motor board after capacitor change

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