This circuit is from a Hands-On Electronics from the 90s. The integrated amplifiers used are well known. The range is a few tens of meters depending on the resistance of the cables.
Any general-purpose transistor can be used in this circuit that generates a rise ramp that can be...
Found in a 1965 Electronic Design, this circuit can be made with modern equivalent transistors. The...
The voltage comparator used in this application is the NCX2220 from NXP. What this circuit does is...