This circuit was found in a documentation of the 80s, having didactic purpose. For R1 values between 10k to 1M can be used. Transistors are general purpose types.
This 3 + 3 V symmetrical source circuit uses an old operational amplifier. The circuit is from an...
This converter that allows high voltages to be obtained from batteries was found in Radio...
This line protector circuit was found in a 2002 documentation, but it is totally current and...