. Rare and Ancient Equipment A10 Data Sheet free download

File name A10 Data Sheet.PDF

DC NANOVOLT AMPLIFIER MODEL A10 The EM A10 is a low level amplifier module for sensitive measurements, data collection and systems, where signals below 1 nanovolt may be measured. It is ideal for the input unit for precision voltage measuring systems, requiring voltage sensitivity for measuring low noise and low impedance sources. The noise level of the A10 is equivalent to a perfect resistor of 20 ohms. When used with a digital voltmeter, steady one nanovolt digits may be displayed, with a response time constant of less than a second. The input voltage stability of the A10 is very high, with the drift around a nanovolt per degree C. The input connectors are made from pure copper. The input impedance is very high, and is time dependent, determined by the internal loop gain of the amplifier. The very high DC gain of greater than five million million means that high overall gain may be used, controlled precisely by feedback resistors, thus ensuring a good degree of linearity with the accuracy defined by the feedback resistors used. Despite the gain, the A10 is stable with 100% feedback. This allows a filter capacitor to be used across the feedback resistor to control the rise time and noise from the measurement circuit. The loop gain is reduced from the DC figure of five million million at the rate of 30 dB per frequency decade to unity at 20 KHz. This determines the response time of the amplifier, which will vary according to the set gain. The A10 can deliver 2 milli-amps of current from its output and so the set gain will determine the level of output signal at low values of gain less than 1,500. The internal 'low' feedback resistor is 1 ohm, and so if a gain of unity is set by connecting the output to the feedback terminal directly, the maximum output voltage will be 2 millivolts. The internal feedback resistor needs to be this low, because the noise generated by this resistor is in series with the input noise, and any higher resistance would cause a significant increase in the total A10 noise. The power consumption is very low, making the A10 suitable for battery powered applications. The minimum supply voltage is plus and minus 5.5 volts and the quiescent current consumption is 1.5 milli-amps. Care is required over the choice of power supply, if batteries are not to be used, to ensure that the very low noise of the A10 is not degraded by series mode or common mode noise being allowed to interfere with small signals. The A10 has very high rejection of common mode noise, but at nanovolt levels great care must be taken. The A10 is small enough to mount on a p.c. board if required, and the case is made of heavy gauge Mumetal to give an extra degree of magnetic and electrostatic screening. The voltage and current offset controls are accessible with a small insulated trimming tool through the two holes in the front. Care must be taken with these adjustments. DC NANOVOLT AMPLIFIER MODEL A10 Noise