We found this CMOS circuit in a 1978 publication. It allows you to use a standard calculator keyboard with 16 keys for encoding in hexadecimal.
This amplifier has a few Watt output, using old transistors. The speaker is 45 ohms, but with...
This circuit is from a 1965 Motorola manual. It can be implemented with a common 2N2646 and a 106...
This circuit, in addition to transforming a sinusoidal signal into a square, shifts its phase. The...