The PHILIPS PM 3330is a cathode-ray oscilloscope with a wide rangeof applications. This is obtained by providing the apparatus with plug-in units which covervariousapplication facilities. The basicoscilloscope contains a vertical (Y) amplifier with a constant bandwidth and gain. The total gain and bandwidthof the vertical(y) chan- nel are dependent on the type of plug-in units used. The horizontal (X) channel contains a time-base gene- rator and an amplifier.