|The Heathkit story
The Electronic Switch ID-22 came on the market in 1964 and was produced until 1970. It was the successor of the S-3 that came on the market in 1956. There is only minor differences between the S-3 and the ID-22. In 1971 the ID-22 was replaced by the ID-101, which in turn was replaced by the ID-4101 in 1977. The ID-22 makes the oscilloscope dual channel. At the time most oscilloscopes was only single channel so it came in handy. A disadvantage is that it reduces the bandwith.