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regulator IC) to the card together with an appropriate
heat sink. Make sure the U28 lead pads on the PC DC
card don't touch the heat sink. Disconnect the +5 V
supply at the + V DC and GND pads and connect your
unregulated 8-10 V DC power supply to these pads.
This on-card regulator will handle up to I ampere of
current and is useful for system expansion. Do not use a
plastic cover for your PC card when this on-card
regulator option is used. Air How is needed to permit
the regulator to operate properly.
Appendix F - Board Layout, Parts List, and Assembly Instructions 77
3. COSMAC VIP Expansion Notes
a. Soldering the PC Board
b. Voltage Regulator Option
An unregulated 8-10 volt DC power supply can
be used with the COSMAC VIP card if desired. Cut
LK1 on the PC card. Add U28 (a 7805, 5-volt
c. Additional 2048-Byte RAM Option
To increase your COSMAC VIP RAM to a total of
4096 bytes, add U20-U23 to the PC card by plugging
units into the four sockets provided. Measure the power
supply current to be sure it does not exceed the capacity
of the +5 V DC power pack supplied with the VIP (600
mA). If you require additional power supply current use
a regulated +5 V DC supply capable of supplying I
ampere or use an unregulated 8-10 V DC supply with
the voltage regulator option on the cards.
In the event you wish to make some changes or
add components requiring soldering, you should have
some experience building electronic kits. The PC
board pads are small and close together requiring
extra caution when soldering to avoid shorts or solder
bridges. Use a low-heat, small-tipped, grounded
soldering iron. Keep it clean. Use small gauge, rosin
core 60/40 solder. Preheat the connection and apply
just enough solder to "wet" the connection. Avoid
using excessive amounts of solder because it will flow
through the plated-through holes and form "blobs"
on the top of the card. Excessive or protracted heat
from the soldering iron can damage some of the
components.