CK3 Alarm Clock and Thermometer
(C) Lucid Technologies
13
half of the case.
2.6 Switches
The switches must now be wired to the CK3 circuit board. Remove the 74HC165 chips (U7
and U8) and store them in a safe place while soldering to the CK3. Schematic sheet 5 shows the
switch inputs to the CK3. One side of each switch is grounded and this ground can be daisy-
chained around the switches, reducing the total number of wires going to the CK3. The row of pads
closest to the labels (SW1-SW7) are the ground pads, the row closest to RN2 are the signal pads.
Allow enough slack in the wires so that the case can be opened to change option jumpers.
Lucid Technologies standard software for the CK3 expects all the switches to be normally-
open, in other words, the input is active when the signal line is grounded. The software also assigns
the following functions to the switch inputs.
Switch Function
SW1
Alarm1 set (A1set)
SW2
Alarm1 enable (A1enb)
SW3
Alarm2 set (A2set)
SW4
Alarm2 enable (A2enb)
SW5
Hours set (Hrset)
SW6
Minutes set (MNset)
SW7
Time set (Tmset)
The alarm_set and alarm_enable switches may be combined into one switch in the form of a
center-off toggle.
6.2 Final Checkout
Put the 74HC165s back in their sockets. Connect the DB1 as it was for the functional
checks. Plug-in the wall transformer and attach it to CK3, J1. Try setting the time-of-day and
alarm-time. If none of the switches work you may have inserted a 74HC165 upside down. Check
that the alarm LEDs blink when setting the alarm-time and are on continuously when the alarm is
enabled. If switches don’t perform the anticipated function you may have wired them to the wrong
SWX pad on the CK3. Correct any errors and check again.
6.3 Final Assembly
The last construction step is to clean the board. If you used organic core solder just rinse the
board in warm water. If you used acid core solder try scrubbing it with an old toothbrush and
rubbing alcohol.
Attach the CK3 circuit board to the bottom half of the case using the four self-tapping
screws that came with the kit. Insert the front panel into the most forward slot such that the red
plexiglass window is on the inside. Insert the DB1 circuit board into the slot behind the front panel.
Insert the rear panel into the rear slot so that the hole lines up with the connectors. Place the top on
the case being sure not to pinch any wires in the seam. Use the long self-tapping screws that came
with the case to securely close the case. Attach the wall transformer to the clock via the hole in the
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