The circuit below is suggested by National Semiconductor in technical documentation on the LM3909. The circuit is powered by a single battery and has a very low consumption.
The transistors used in this crystal tester are general-purpose types. The circuit was found in...
We found this shield circuit in a 1991 technical documentation. The phototransistor can be...
August 2017 - Mouser Electronics is making STMicroelectronics' Analog and Digital MEMs available in a...