from Radio Shack:
a.
(8) TIP-120 transistors
b. (8) heat
sinks for above
c. (8) 1/4W 470 ohm
resistors
d. (8) 2.5A 100 V PIV
diodes
e. (4) 1/4W 220 ohm resistors
f. (2) 74LS04 hex inverters
g.
(1) large instrument box
h. (1)
276-160 circuit board
i. (1) 25-pin
cable
j. (1) 25-pin connector kit
k. (2) 9-pin connector kits
l.
(4) momentary push buttons - normally off, temporarily on
m.
(1) 3-way center-off switch
n. (1)
2-way switch
o. (1) package of small
diodes
p. (2) IC 14 pin sockets
q. (1) 7805 power regulator chip
r.
(1) heat sink for above
s. (3) 0.1
uF capacitors
from a local well
stocked electronics store:
a. (4)
30V 5W zerner diodes
from a motions control outfit such as:
Torque Transmissions (TorqueTran@aol.com,
(http://www.torquetrans.com)1-216-352-8995)
(60:1, use final roller reduction of 40:1) or
Allied
Devices (100:1, use final roller reduction of 24:1) (1-516-223-9100)
or
Andy Saulietis' hard plastic gear
reducers (iss@pvtnetworks.net)
or
Larry Myers' Byers gears
(http://www.mountaininstruments.com
or larrym@foothill.net) or
American
Science and Surplus (http://www.sciplus.com/)
look for motors with gear heads for ~$5 removing the motor or
Martin
Sprockets (http://www.martinsprocket.com/contact.htm)
Harmonic Drives
(http://www.harmonicdrive.net/)
RS-Components worldwide
(http://www.rs-components.com/)
Small Parts Co (http://www.smartparts.com)
1 gear reducer per axis ~$100 (aim for
gear reducer multiplied by final roller reduction to equal about
2400:1, this gives 1/4 arcsecond per microstep, exact microstep size
is entered in the CONFIG.DAT file)
Jameco Electronics
Oriental Motors (the 400
step motors are very nice)
Surplus stocks are a moving target!
Look for steppers at surplus houses
a. (2) stepper motors: 6-12 VDC .3 to 1
amp/phase 20+ in-oz torque ($2+ and approx 2"x2"x2"
size with 1/4" shafts), preferably 6 leads, but 5 or 8 lead
motors will do, 4 lead motors are bipolar motors and not suitable,
preferably 200 steps per revolution (1.8 deg full step size)
b. (2) cables: Jameco DB9 M-F 6' connector 25700 $4.95 + Jameco DB9M connector 15747 $.35 + 15721 hood $.32,
c. LED test unit: Jameco 152856 LEDs for winding testers $.12 + Jameco DB9M connector 15747 $.35 + 36 470 ohm resistor Jameco 31165 $.89/100
Jameco 237472 or MPJA's four lead bipolar stepper - only needs to have minimal holding torque to operate focusers and field de-rotators
PIC Servo controller by Kerr, available from Jameco Co #184989 $180, RS232->RS485 converter #184971 $60
part number S2-2500-B from US Digital, seller of Hewlett-Packard encoders
The optional MC3479 field derotator chip which replaces the discontinued SAA1042 can be ordered from Jameco Electronics, part number 25216 (MC3469P), price $5.