VRC2000 Installation and Operations Manual Page 107
Technical or Setup Assistance
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These conditions inform the VRC2000 whether outbound calls have been
terminated (answered) or not.
Digital Voice Synthesizer
The VRC2000’s synthesized voice reporting is done by National
Semiconductor’s Mozer MM54104 digital voice synthesizer. This integrated
circuit is a Vocorder (energy from an actual human voice recording is broken
down into bits, synthesized to recreate an addressable vocabulary word by
word).
Refer to Appenidix J: Schematics (Page 129) for digital voice synthesizer
circuitry. U12 is the MM54104 and its associated memory (U1, U3, U8 and
U10). These memory devices are 27C256 EPROMs, which contain almost
800 words (library/vocabulary) accessible to the unit.
Power Supply
The VRC2000 was designed to operate on an AC line of either 117Vac or
234Vac. Selection of line voltage is accomplished by selecting the proper
Molex connector, which ties the line cord to the VRC2000’s transformer.
The AC line transformer produces two output levels at its secondary
windings. One is 31Vrms, which is rectified and input to the linear
regulators; the other, 17Vrms, powers the digital regulator.
The digital circuitry on the VRC2000’S PCB is powered by VR1, a 7,805K
5Vdc regulator. VR2 and VR3 provide +/-12Vdc (7812T and 7912T) for the
linear chips. The digital voice synthesizer operates at a VDD of 9Vdc, so a
1N5223, 2.7V Zener diode is in series with its supply line.
The MC146818 clock and the RAM (U27, a HM6264) are both powered by
the 3.6Vdc internal-lithium battery when the AC line drops below 72Vrms.
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