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The address is on the NZ&A Time home page.
This 1987 'Classic' bleeper
box was built in 1987 when VNG was temporarily off the air. It has
some rough edges but it has worked OK for the last 15 years. The
'circuit' elements are as follows:
(a) A cheap analogue clock mechanism "with second hand", which puts out a pulse each second to energise a solenoid that moves the second hand forward one step. The solenoid is replaced by a 1 kOhm resistor and the pulse fed through an amplifier to the divider chips. The clock runs off a separate 1.5 V battery
(b) Note the remainder of the circuit runs off a 9 V battery.
(c) One transistor amplifier to amplify the small solenoid pulse.
(d) One transistor inverter and driver for 'Seconds' LED and Piezo buzzer.
(e) 'Divide by 10' Integrated Circuit - 4017 drives '10 Seconds' LED.
(f) 'Divide by 6' Integrated Circuit - 4017 drives inverter transistor.
(g) 556 Timer IC to lengthen the pulse to 400 ms (later changed to 500 ms as in VNG) - output drives 'Minute' LED and Piezo buzzer.
(h) The output of the 555 is also used to reset the two 4017 - the diode prevents this being done each second.
This is a pretty basic model that generates 59 Second Markers and 1
long (400 ms) Minute Marker. It does not shorten Second Markers 55
to 59, and does not omit Second Marker No. 59. However, it has been
used for grazing occultations and does the job.
(2003 MODIFICATIONS TO 1987 PROTOTYPE)
This box is a portable “transfer standard” to maintain and carry with you a ‘local’ time signal of 59 short beeps (pips) plus a long 0.4 sec beeeeep on the full minute. At the start of the job, the box is started by manually synchronising it “by ear” with a reputable time signal (GPS, WWV/H, or Telstra 1194 on a fixed landline telephone). The box then keeps bleeping, can be taken to an observation site, and can be used there for an hour or so, before the time slowly ‘drifts’ too far out of calibration. After the observation, the box is checked again with an independent standard time signal.
In the box is the core of an analog quartz alarm clock with a second
hand, and we use the ‘second’ pulses that drive the solenoid that moves
the second hand. Clock quality varies but most keep time to a couple
of seconds per day, which is less than 0.1 second over a one hour period
(most of the time error is a steady drift, for which we can correct by
checking the calibration before and after an event).
Start as follows: