Acousto-optic digital level detector circuit diagram

The acousto-optic digital level detector circuit that will be introduced in this article is an acousto-optic digital level detector circuit composed of a 555 time base integrated circuit and a small number of peripheral components . The detector has good practical effect and is easy to make.

When probe A is floating, transistor BG is cut off, control terminal 5 of the time base circuit NE555 is at high potential, the controlled audio oscillator composed of NE555, R3, R4 and Cl does not vibrate, the speaker is silent, and pin 3 of NE555 The pin outputs a high level, and the LED is cut off and does not emit light, that is, the detector is silent and lightless. When probe A contacts the logic "O" level, pin 4 of the reset terminal of NE555 shows a low level, and the circuit is reset, so that the audio oscillator still does not vibrate and the speaker is still silent, but at this time, the output of pin ③ of NE555 is low level. flat, the LED is on and emits light, that is, the detector has light and no sound.

As shown in the figure, the probe A of the detector can be made by using a suitable copper wire. The transistor can be a 3DK3 or 3DK7 switch tube, the LED can be a red light-emitting diode, and the power supply can be a 6V laminated battery. All components are housed in a pocket radio case. When installing, pay attention to the location of the LED and speaker on the casing, and lead the probe and ground wire out of the casing.