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.
We found this timer circuit in a publication in the 90's to turn off a device powered by 4...
This circuit is suitable for use with 1400 kHz range FI receivers. Changes can be made to other IF...
The transistors of this 12 V x 150 mA power source can be BC558 for PNP and BD135 for NPN. The...