MSE570_1 Datasheet, PDF (5/5 Pages) List of Unclassifed Manufacturers – Bipolar Stepper Motor Drive Board

Oscillator operation
The normal method of oscillator operation is as follows:
1. The oscillator is started at the base speed by
switching the run switch on with the base/high speed
switch set to base. This base speed is a frequency
offset and should be chosen to be safely within the
pull-in capability of the motor/drive combination, and
ideally above the resonant frequency range. This
base speed is defined by C-freq and the setting of
VR1.
2. The high speed may be selected by switching the
base/high speed switch to high. The oscillator will
then ramp up to the high speed. This high speed is
set by VR2, whose range is defined by R-freq and
C-freq. The ramp rate is determined by the time
constant of R27 (100KΩ) and C-ramp.
3. The oscillator may then be slowed back down to the
base speed by switching the base/high speed back
to base.
4. When the speed has dropped down to the base
setting the oscillator may be inhibited by switching
the run switch off. The motor should only be started,
stopped or have a direction change whilst at the base
speed.
Using the graph below select a value for C-freq for the
chosen pot VR1
Required base speed (Hz)
VR1=100KΩ
100K
10K
VR1=0Ω
1K
100
VR1=1MΩ
10
1
100p 1n
10n 100n 1µ
C-freq (F)
Then from the ratio of the maximum running speed to
the base speed, use the following graph to select
R-freq.
Max speed/base speed
100
High speed
10
Base speed
1
2
3
4
1
0.1
1
10
100
VR1+10KΩ/R-freq
Component selection
The following components need to be soldered onto the
PCB:
IC8
CD4046 CMOS PLL IC (used as VCO)
R-freq resistor 1KΩ-1MΩ
(typ 5.6KΩ)
C-freq capacitor >100pF
(typ 10nF)
C-ramp capacitor
(typ 10µF)
P3
optional molex connector if using front panel
controls
The following external components are required to
complete the oscillator:
VR1 pot
VR2 pot
0 - 1MΩ
1 KΩ
(typ 1 MΩ)
First determine the base speed and the maximum high
speed you wish to obtain.
Caution!
1. SERIOUS DAMAGE WILL OCCUR if any motor lead
is connected or becomes disconnected whilst the
drive is energised.
2. The drive board should always be mounted such that
the heatsink fins are vertical i.e. with the board on
edge, and adequate clearance be given top and
bottom i.e. 25 mm minimum. When rack mounting
the board there should be at least a 15 mm
clearance between the heatsink and an adjacent
board. If the airflow around the unit is restricted, then
force air cooling should be employed.
3. When using the drive at high ambient temperatures
or at slow speeds or at standstill, whilst at high
current settings, it will prove advantageous to employ
forced air cooling.
4. Motor and power supply connections should be
made with at least 32/0.2 mm wire due to the high
peak currents flowing. All other control wiring may
use 7/0.2 mm.
5. Good engineering practices should be employed in
the commissioning of this product and should be
made to adhere to all relevant regulations.
MSE570 data sheet
Page 5 of 5
Issue 002