Table of Contents
Advertisement
BMX SERIES III CONSOLE
8.2 CLOCKS AND TIMERS
BMX III meter panel clock and timer positions are defined in Figure 2.4 (Section 2.3.2). These positions
accommodate the TD-2 Digital Clock (PR&E #99-179-1) or the TD-171 Digital Slave Clock (PR&E #99-
312-1), and the DT-4 Digital Timer (PR&E #99-180-1).
8.2.1 TD-2 Digital Clock
The TD-2 is a six-digit (hours, minutes, seconds) general purpose digital clock. The only connection
required at the rear of the clock is the external power source (PR&E #50-17, supplied with the clock).
Setting the clock requires the use of the supplied magnet tool (PR&E #90-151) to operate the Hall-effect
switches located immediately behind the front panel lens. These switches are centered beneath the three
pairs of digits about 1/4 inch above the bottom of the bezel, as shown in Figure 8.1.
DIGICLOCK
TD-2
PACIFIC RESEARCH & ENGINEERING CORP.
PR&E #90-151
FAST
SLOW
HOLD
SET
SET
FIGURE 8.1 TD-2 DIGITAL CLOCK
To adjust the clock, place the end of the adjusting magnet against the panel in the appropriate area. Use the
FAST SET switch to advance the hours, and the SLOW SET switch to advance the minutes. The HOLD
switch will cause the hours, minutes and seconds to stop and hold at their current setting.
CIRCUITRY
The TD-2 is designed around MM5314 digital clock integrated circuit U3. The time base is supplied by
crystal oscillator/divider circuit Y1 and U1. The voltage doubler circuit of Q1, Q2, C4, CR1, CR2, and
C5 provides the high positive voltage required to pin 15 of U3. The display multiplex frequency is
determined by C3 and R2.
The segments of displays DS1 through DS6 are driven by transistors Q4 through Q10, and the digits are
selected by inverters Q11 through Q16 and drivers Q17 through Q22. Hall-effect switches U4 through U6
are magnetically activated to set the clock's FAST, SLOW and HOLD functions.
REVISION B
203
PACIFIC RESEARCH & ENGINEERING
Advertisement
Table of Contents
