Armstrong later used Fessenden's heterodyne principle in his superheterodyne receiver "(below)". Regeneration, the superheterodyne circuit and wide-band frequency modulation or FM. There are two types of RF receiver modules&colon; superheterodyne receivers and superregenerative receivers. The superheterodyne receiver offers superior sensitivity, frequency stability and selectivity. A cascode circuit is very useful as a multiplying mixer circuit in superheterodyne receivers. Regenerative detectors were sometimes also used in TRF and superheterodyne receivers. By the mid-1930s, commercial production of TRF receivers was largely replaced by superheterodyne receivers. It used an FM transmitter section and a double superheterodyne receiver. The superheterodyne receiver has several advantages over previous receiver designs. Later he even built a superheterodyne receiver. After the first experiments, Losev built regenerative and superheterodyne receivers, and even transmitters. One common form is the IF (intermediate frequency) transformer, used in superheterodyne radio receivers. The receiver is generally one of two types&colon; a super-regenerative receiver or a superheterodyne. The diagram at right shows the block diagram of a typical single-conversion superheterodyne receiver. This can be exploited as a frequency-changer in superheterodyne receivers.