This PCB Layout does NOT include the
new added feature of field rotation! For a description of my
fieldrotation daughterboard go to my Fieldrotation page.
NOTE 2:
Many people asked me to sell them one of my circuit boards. I do
NOT manufacture or sell those boards!
It is actually quite easy to make them. I however will be happy to
answer any question about the process of building one.
NOTE 3:
Neither PCB's manufactured using my
design nor the design itself may be sold. The use of the
content of this page for any kind of publication needs the
agreement of Mel Bartel's and myself.
Also see my CompuDob
page that displays my 6" Computerized Dobsonian telescope
Preface
I assume that the reader is familiar with the basic process of etching
printed circuit boards. If not, I recommend to look through the
reference section at the end of this page.
The reader has to take all necessary safety
precautions while handling the chemicals for PCB etching!
Those include: Rubber Gloves, glasses to protect the eyes, apron,
suitable and well-ventilated working area.
Materials needed
One single sided copper clad board 180x130 mm
Iron-on toner transfer foil/paper or laser printer transparencies
Postscript capable Laser printer or Xerox copy machine
Etchant (Ferric chloride)
Scotch brit cleaning sponge for cleaning the board
Etch resistant pen (Decon) for touching up badly transferred traces
Electric Iron
You can also expose the artwork on the board. In that case you will
need a photosensitized copper board and all the chemicals to develop
the board.
Layout
Download the 120k
ZIP file with the Postscript/Acrobat files and unpack it to a
directory on your hard disk.
The archive contains the following files:
ARTWORK.PS / ARTWORK.PDF
is the unmirrored Artwork files in
postscript/Acrobat format
MIR-ART.PS / MIR-ART.PDF
is the mirrored Artwork files in
postscript/Acrobat format
SILK.PS / SILK.PDF
is the unmirrored Silkscreen files in
postscript/Acrobat format
MIR-SILK.PS / MIR-SILK.PDF
is the mirrored Silkscreen files in
postscript/Acrobat format
ALTAZ.JOB
is the JOB file for the PADS-PCB program. If you have PADS-PCB you
can edit the Artwork.
Important:
If you are using Toner transfer paper then you must use:
ARTWORK.PS or ARTWORK.PDF and MIR-SILK.PS
or MIR-SILK.PDF
If you want to expose the artwork on photosensitized board then
you must use:
The artwork unmirrored (for the PCB, only use the supplied high
resolution .PS Postscript file. This one is a low resolution
.GIF file) (Click on the small icon to see larger
image)
The artwork includes a large surface-area groundplane for
better circuit stability. The ground traces across the
board are broader for the same reason.
Above the transistor pads are the big 3mm mounting holes
for the heatsinks. There is enough space on the board to
mount the transistors/voltage-regulator + TO220 heatsinks
horizontally.
For offboard connections I used single row straight PCB
plugs.
The silkscreen unmirrored (for the PCB, only use the supplied high
resolution .PS Postscript file. This one is a low resolution
.GIF file) (Click on the small icon to see larger
image)
The black lines are jumper wires.
PP2,PP3 etc. stands for connections to the referring pin
of the parallel Port
M1 is the output to the Altitude Motor. M2 is the output
to the Azimuth Motor.
The long 8-pin connector is the out/input to/from the
handpad.
+12V and GND are the pins for offboard voltage and ground
connections, like the 12V connection to the stepper motors
and the ground connection to the parallel port.
On some diode symbols, the line to mark the cathode is
missing. However the square pad marks the cathode.
The schematic (Click on the small icon to see larger
image)
Pin 7 and 14 of the Hex inverter are of course connected
to Ground (pin7) and +5V (pin14). They don't appear on
the circuit because the PCB software handles all
Ground/Power connections by itself.
The color coding for the handpad cable is my invention.
You can of corse use whatever colors you want for the
handpad wires.
The following photographs show the ready assembled PCB board.
The bottom side gives a little impression about the quality of
etching that can be achieved by using Iron-on-Foil. (Click on the small icon to see larger
image)
The top side shows the spacing of the assembled
components. (Click on the small icon to see larger
image)
The next two photographs show my version of the handpad. (Click on the small icon to see larger
image)
I used a momentary On-Off-On
switch for the Init-button .
This is a picture of my electronic-box design. (Click on the small icon to see larger
image)
Using the single row PCB-plugs for the offboard connections you
can provide for clean wiring and avoid mistakes.
