Optical sensor for PC (CB20548E)

This circuit was found in a PC documentation from 1996. It can be used as a shield with modern microcontrollers.

Simple MW Radio 2 (CB4360E)
Originally this circuit is from an English magazine, but I found it in Argentina's Radio Chassis...
Audio Limiter (CB948E)
We got this circuit in a publication of 1987. This is an audio limiter, a circuit that cuts peaks...
TPS7A90 Low Noise LDO Evaluation Kit - Texas
Mouser Electronics has in stock the Texas Instruments TPS7A90 Low Voltage Dropout (LDO) Linear...