Time Electronics 1010 DC Voltage Calibrator - Manual (Page 4)

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1010 Technical Manual 4
1.3. Power Unit
The 1010 is supplied with a mains/battery power unit. This can be configured when ordered
for either 115V or 230V AC, 50/60Hz. See section 2.7.3.
1.4. Circuit Description
The calibrator employs a temperature compensated zener diode as the basic reference
source. This provides the input to a FET chopper amplifier system which operates in a feed-
back stabilised mode, and has a gain value determined by a set of precision metal film
resistors which are selected by a 5 decade thumbwheel switch. The output voltage is
variable from 0 to 9.9999 volts in 5 ranges. An output resistance of typically 0.05 ohms is
maintained on the top three ranges; the maximum output current that can be drawn on
these ranges is automatically limited to 30mA. This is to prevent damage to the circuitry in
the event of accidental short circuit etc.
The lower ranges have an output resistance of 1 ohm and will supply current up to the short
circuit value. To ensure complete reliability the range switch employs two contacts in parallel
for each position - even if a contact fails the 1010 still functions correctly.
1.5. Applications
The uses of the instrument include the calibration applications of conventional voltage
potentiometers. A 1010 in these applications has the advantage of requiring no
standardisation and being able to supply much higher output currents without loss of
accuracy. Long term stability is inherent since standardisation is not required.
Other applications as a precision voltage source include calibration, linearity and gain
stability measurements, etc., on D.C. amplifiers, digital and electronic voltmeters,
transducers and as a variable low current power supply or backing-off voltage. The 10
ppm/HR stability and low noise levels are of particular interest when an extremely stable
voltage is required rather than a high accuracy calibration source.