©1999 Hamtronics, Inc.; Hilton NY; USA. All rights reserved. Hamtronics is a registered trademark. Revised: 2/4/03
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latches.
The autopatch latch has some ex-
tra circuitry with it to provide toll call
restriction. U4 is a counter which
keeps track of which digit is received
after the autopatch latch is turned on.
When the autopatch is off, the not-Q
output of U6A is hi, keeping U4A/B
reset. However, when the four digit
code is sent to bring up the patch,
U6A turns on, and the reset signal is
removed from U4, allowing it to count
digits. The Q output of U4B remains
lo until the second digit after the
autopatch turns on. If a 0 or 1 is re-
ceived during the first digit after the
patch is brought up, U3B, which is
used as an AND- gate, is satisfied that
it has two lo's, and it provides a clock
input to autopatch latch U6A. Since
the data input is wired lo, that causes
the output of the latch to assume the
data input (lo) condition, thereby kill-
ing the autopatch. If any other digit is
received as the first digit of a phone
number, U3B is not satisfied, and the
autopatch remains on. On subsequent
digits, digit counter U4 removes its lo
from U3B, so the patch will not be
turned off by any received digit, even a
0 or 1.
CONSTRUCTION.
The pc board is double-sided with
plated-through holes. Because it is
more difficult to unsolder from this
type of board, be sure parts are ori-
ented properly and of the correct
value before soldering. Pc traces are
close together, so use a fine soldering
iron tip.
During construction, orient the
board right side up as shown in the
parts location diagram. The top side
as shown has the pin number mark-
ings. Also refer to the parts list and
schematic diagram during construc-
tion.
Before assembly, it is important to
decide whether or not you will use the
three digit key for controlling all of the
functions. If you will want to control
some or all of the functions with only
a single digit code, it is necessary to
break some pc paths on the top of the
board which will be concealed later by
ic sockets. If you want to modify the
pc board in this way, refer to the sec-
tion on Programming prior to assem-
bly.
CAUTION
.
The CMOS ic's used in
this kit are all static sensitive; so han-
dle them with care. A grounded wrist
strap should be worn whenever you
pick up an ic. Do not open the pack-
ages containing the ic's until you are
ready to install them, and then handle
them only with suitable static control
measures.
a. Install ic sockets oriented with
notches as shown, and solder.
b. Install the led's on the board,
observing polarity. The positive lead
is longer on some led's. On others,
there is a flat on one side as shown on
the parts location diagram.
CAUTION
:
Small LED's are heat
sensitive. Keep the LED's up off
the
board about 1/4 inch and solder
quickly, applying minimum heat to
avoid damage.
c. Install the remaining parts
other than the dip ic's, according to
the parts list. Be sure to observe po-
larity on the diodes, transistors, U12,
and the electrolytic capacitors. Verti-
cally mounted parts are illustrated
with a circle indicating the body of the
part, and the diode symbol next to
CR2 on the diagram indicates the po-
larity.
d. Check over construction to be
sure all parts are installed in proper
places and with proper polarity and
that solder connections are good.
Look for things like cold solder joints
and solder splashes. Note that one
hole above U5 is a "via" used only to
make a connection between the top
and bottom of the board. Nothing is
installed in this hole. Note also that
programming wires will be installed
later.
e. Using static protection de-
scribed earlier, carefully unpack the
dip ic's and install them in the sock-
ets. Be sure to orient them as shown,
according to either dot or notch on the
end of each ic. If any conflict between
notches and dots on an ic, the notch
(which only appears on one end) takes
precedence. Sometimes, RCA cmos
ic's have a test dot of some color (eg.
blue) on one end, and such dots can
be confusing because they can appear
on either end. Ignore such dots if the
ic also has a notch or white bar on
one end, which would indicate the pin
1 end. Be careful to engage all the
pins in the socket; don't let any leads
bend over.
PC BOARD HANDLING PRE-
CAUTION.
Be careful whenever you handle
the module. Even though static dam-
age occurs most easily before ic's are
installed in their sockets, damage can
still occur to the ic's in a completed
module if a static discharge occurs at
any part of the board during handling.
Although wrist straps are not abso-
lutely necessary just to handle the
completed board, you should make it
a habit of discharging your hand to a
grounded object before touching a
CMOS module.
INITIAL TESTING.
Although it is not necessary, you
may wish to test the tone decoder por-
tion of the board before you proceed
with programming. To do so, connect
a power supply ground to the ground
trace at one of the four corners of the
board, and c10 to +15 Vdc to
the dc input at pad 2. Connect a
source of touch tones to audio input
pad 1, with a level between 100 mV
and 2V p-p. The outputs at the left
two rows of programming pads should
have a CMOS logic level (close to 0
and +5V) with the hi corresponding to
reception of a valid touch tone digit.
The "mute" signal should also appear
at mute pad 3 at the edge of the board
whenever any valid digit is received.
PROGRAMMING.
The following discussion is an at-
tempt to simplify the steps required to
plan how to use the various functions
on the TD-2 module. There are many
variables involved, but breaking it
down like this should make it easier
to consider everything.
Read through the paragraphs
which follow, and take actions where
appropriate. Table 1 is a sample of the
type of plan you should make. This is
a typical setup in an amateur radio
repeater installation, and it is the pro-
gramming we use for wired units at
the factory unless something else is
requested. The chart shows the corre-
spondence of the decoder output pads
with the function-input programming
pads for each function. It also shows
the complete command sequence de-
sired for each function, based on hav-
ing to send the three "key" digits plus
the function-indicator digit for each
command. You should make a plan
like this for your installation, noting
what each function will be used for.
There are 12 momentary functions
available. 10 of them may be used ei-
ther for a simple momentary function
or as the input to control a latching
function. The E0 and E1 functions
may be used only as momentary func-
tions.
(Refer to theory of operation for
more information on these circuits.)
The five latching functions are
similar except that the R function, be-
ing normally used for control of a re-
peater, has reversed nomenclature,
ie., the "R0" function causes a short to
ground at the latch transistor output
pin, and the "R1" function causes an
open circuit. The other latching func-