This circuit is useful in liquids level or proximity detection. It operates detecting the distance from the target by reflection of an infrared beam. It can safely detect the level of a liquid in a tank without any contact with the liquid itself.
This circuit is intended to signal, through a flashing LED, the exceeding of a fixed threshold in room noise, chosen from three fixed levels, namely 50, 70 and 85 dB. Two Op-amps provide the necessary circuit gain for sounds picked up by a miniature electret microphone to drive a LED.
These analog supply rails can drive precision op amps, such as the MAX400 and OP-07, whose input common-mode-rejection and output-range specifications are 2 to 3V within the supply rails. Thus, the rails are good enough if the -5V output is less than -3V and the 10V output is more than 8V.
The chronograph works in the normal way, by timing how long it takes a projectile to break two infrared beams spaced 3 inches apart in the tube. The spacing is critical as any offset will result in a measurement error. The minimum measurable projectile speed is approximately 38.1 ft/sec.
With network-analyser you can measure only up to 6 GHz. For higher frequencies you have to use generator and power-meter. This article describes how does the author measure such relays available from various manufacturer such as Narda
for spectrum analyser
with a nonelectric VOM