Precision light level detector (CB20699E)

In this circuit R1 has 2M5, R2 and R3 are 5M obtaining a detection current for the diode of 0.5 uA. The circuit is from an 80's documentation.

Rail to Rail Oscillator 555 (CB9099E)
Found in an Electronic Design from the 80s, this circuit generates a 500 Hz signal and can be used...
Voltage Doubler 555 (CB25543E)
This circuit, which can generate voltages up to 25 V, was found in the December 1992 issue of...
Product Detector (CB4223E)
Found in a 1980s publication for amateur radio, this circuit employs an MC1596G which is a...