The PHILIPS AC-Millivoltmeter PM 2454 is a sensitive and accurate measuring instrument suitable for measuring voltages from 50 µV.. . 300 V in the frequency range from 2 Hz. . . 2 MHz The instrument is fully transistorised (Silicon transistors), mains-powered and of modular construction. It can, therefore, be used both as a table model and in combination with other equipment mounted in standard racks. A special feature of this AC-Millivoltmeter is its high input impedance of 10 MΩ//25 pF. On account of this it is also possible to measure voltages from high-ohmic sources. The 12 measuring ranges of 1 mV. . . 300 V f. s. d. overlap so that a high reading accuracy is obtained. The moving-coil instrument is provided with a mirror scale with the ranges 0-30 and 0-100 as well as a dB scale from -20 dB.. .+2 dB (total scale span -80 dB. . .+52 dB). The indicating speed can be switched from "FAST" to "SLOW", so that it is also possible to obtain a high reading accuracy at lower frequencies. Due to its large bandwidth the instrument has wide range of applications, e.g. measurements on LF and IF amplifiers, carrier-wave telephony, infra and ultrasonics, etc. The amplifier output, moreover, makes it possible to employ the instrument as a pre-amplifier for special purposes or may be used for connecting an oscilloscope.