This LED diode test is suggested by the Texas Instruments optoelectronics manual. The transformer current can be between 50 mA and 300 mA and the voltage between 6 and 9 V.
The amplifier shown in figure 2 is based on the MAX9715 integrated circuit from Maxim...
This stage for JFETs was found in a 1965 US publication, but is valid for modern components. |...
This circuit was found in a Japanese publication from 1971. The circuit uses components from the...