This dual axis stepper motor drive system represents a new era in high performance operation. Using a bi-level type of drive circuit we have achieved higher speed and more power output from medium sized stepper motors. Full torque is available at all drive rates with no loss at high speed. To achieve high speed with a large inertial load the drive ramps up the speed over a 10 second period.
The adjustment rates selectable by switch are 30%, 2x and 50x. With no buttons pressed the unit will be driving at the King rate (refraction corrected Sidereal rate). The VFO option (if fitted) will alter the RA rate to an adjustable rate encompassing SOLAR and LUNAR (Sidereal +/- 5%). Extra power is used only when the adjustment buttons are used in slew mode. The current in either motor is greatly reduced when they are operating at zero or slow step rates. This also reduces the holding torque but is not serious with a balanced telescope.
As with all stepper motor systems the direction sense of both motors can be altered with jumper links so it is suitable for Southern and Northern Hemisphere use, or if the motor is fitted either end of the slow motion shaft.
This unit is powered from 12V DC. Power consumption depends on the motor type fitted but will be less than 2 Amps when you would need to connect something like a car battery. The STEP5 and STEP4 motors require about 0.5 Amps and we are offering a BATPACK option which will operate the system from 4 'D' cells (large torch battery) and so at great reduction in weight. It is expected that a pack of cells will last at least 7 hours dependent on how often the high speed slews are used. This would typically be two or three astronomy sessions.
Physically, the system comprises a waterproof Drive Box close to the telescope and a 2 metre lead to the Handset. The power supply terminals are on the drive box and the motor leads come out on flying leads with a connector near the motor. The handset is 14cm x 8cm x 3cm. The drive box will be of a size to accommodate the BATPACK if ordered.
In common with all AWR handsets there is a LED in the middle of the 4 direction buttons. In SYSTEM5 the LED will change colour to green if the VFO option is in use and will also flash if it receives a low power signal from the drive box if the BATPACK option is fitted.
This system can drive the AWR motors as follows:
- STEP5 motors up to 500 steps per second at up to 100Ncm torque.
DRAWING OF MOTOR ASSEMBLY
- STEP3 motors up to 400 steps per second at up to 200Ncm torque.
DRAWING OF MOTOR ASSEMBLY
When this unit is to drive a Vixen GP or SP mount using the VIXEN motors we can achieve full load driving capability (100Ncm torque) at 50x Sidereal rate..... We can supply this system for driving the older Polaris mount that has 5 pin stepper motor connectors rather than the modern 8 pin ones.
Can be ordered by itself for fitting to special systems requiring high speed or high torque. Our STEP3 motors can be driven to 2200 steps per second at full torque using chopper drive circuitry. This handset is the only one that provides the necessary speed up from 300 steps per second to full speed.
The photograph shows how it looks without the VFO option.
A special version of the SYSTEM 5 product is available to drive the VIXEN stepper motors. We have a drive board which fits within the handset instead of a drive box. Hence there are two leads to the stepper motors and a 12V input connector on the handset. This model number is SYS5/VIX.
Full size PICTURE of size 33k.