K504UN1B It is made on the basis of FET transistors with p-n junction and p-channel. The K504UN1B microcircuits are a low-noise low-frequency amplifier with high input impedance, made with Pn junction and p-channel field effect transistors, designed to create selective amplifiers, low-frequency sinusoidal and relaxation oscillators, signal amplifiers from high-resistance sensors (piezo, photoelectric, capacitive , radiation detectors).