This circuit uses a transistor as a sensor and operates in the range of 0 to 50º C. We found it in old documentation. Operational equivalents can be used.
This small converter using Only one transistor was published in the Radio Electronics magazine from...
This circuit was found in a Popular Electronics of the 1990s. Its purpose is to expand the scale of...
This receiver was found in old English documentation and any general purpose NPN transistor can be...