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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.

NOTE:  The above is not a full circuit diagram, more a 'logic design flowchart'.  Many essential circuit elements (resistors, coupling and decoupling capacitors, etc.) have ben omitted for simplicity.

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.

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).
 - The 1.5 V ‘D-Cell’ battery runs the clock and this is normally kept going permanently.  The large D Cell has enough capacity to keep the clock going for many years.
 - The 9 V battery runs the ‘divide by 60 circuit’ ICs, the bleeper and the LEDs.  This (expensive) battery only lasts a few hours. Please disconnect when not needed.
 - There is no “ON/OFF” switch.  When the batteries are clipped in, the circuit runs.
 - The toggle switch next to the piezo buzzer only turns the Sound on or off;  the circuit keeps going.
 - The sliding switch in the centre selects ‘SET’ or ‘RUN’ modes; it controls the 4 pushbuttons:  When in ‘SET’ mode you can calibrate the unit.  When in ‘RUN’ mode all pushbuttons are dead..

Start as follows:
1. Insert the batteries.  The circuit will start; you can see the LEDs on the circuit board flashing and hear the bleeper, if switched on.  However, the time is not yet correct.
2. Slide the centre switch up to the ‘SET’ mode.  The four pushbuttons are now active.
3. Synchronise the second beeps as follows:  Using the two black pushbuttons, hold one button down and then hit the other black button a few times briefly (‘tap’ it) until you hear the bleeper seconds running exactly spot on top of the GPS, radio or telephone second pips.  During this “hit and miss” calibration process, don’t worry about the minute markers and LEDs.
4. Once the seconds are OK, put the minute marker in the right place:  Hold down one of the two red pushbuttons, and get ready to press the other red button.  Wait for a GPS, radio or telephone full minute marker, be ready, and then press the other red button briefly during the beginning of the first second of the new minute (i.e. during the long beeeeep) and then release both buttons.  On the next full minute(s), check that the long minute beeeeep is at the right time.
5. Slide the centre switch to ‘RUN’ mode, to bypass the four pushbuttons.  Check the output:
 -  Each second:   Red LED, plus short beep
 -  Every Ten Seconds:   Red LED and One (Yellow/) Green LED
 -  On the Minute:  Red LED and Two Green LEDs, plus long beeeeep
Once the bleeper is running nicely,  keep it going continuously  until you have a chance to check it again after the observation.  It is important to keep the box running and to check it against another time source before and after the observation.  If at the ‘re-check’ a small drift is found, and the temperature of the box has been reasonably stable, work out the correct event time by interpolation.

{If you get stuck, ring Alfred Kruijshoop, Mount Waverley  +61 3 9803 9071}


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