This step of two transistors has a high input impedance due to the use of FET. We can use BF245 for this function and the bipolar can be BC548. The circuit is from an 1975 American documentation.
The circuit shown in figure 1 is suggested by Maxim (www.maxim-ic.com) and makes use of the...
This high impedance circuit uses a 12 V lamp to test voltages in a car. We found it in a Popular...
This circuit was found in an Electronic Design. It makes use of a relaxation oscillator to trigger...