We are a trusted Manufacturer and Supplier of Sound Indicator in India. All of us know it is impossible to separate sound effect and light effect. But this simple circuit makes it possible to vary the effect from simple to complex. This circuit is a sort of running light whose rate of change depends on the frequency and intensity of the sound.
About the Circuit :

• The circuit is build around two counter ICs, IC1 and IC2 as shown in the circuit diagram. The sound signals generated are received by condenser microphone. These signals are amplified by pre-amplifier circuit designed around transistor T1. It should be noted that the amplified level must be high enough to overcome the switching threshold of the counter, while its frequency determines how often counter is clocked. After amplification, the signal is applied to IC1 via P1, which controls the sensitivity of the circuit.
• Since audio frequencies are too high for making a good visual effect, the signal frequency is scaled down by IC1 when S1 connects pin11 with pin15 of IC1, when the switch is in other position, pin2 is connected with pin15, the counter then divides by 1 and the effect assumes a completely different character that no longer resembles a running light.
• The actual running light is provided by IC2, a counter with integral 1 from 10 decoder, which is clocked by the Q0 output at pin3 of IC1 of the ten output of IC2 each of which is connected to an LED, there is always one ‘high’. The ten LED have a common bias resistor R5, an arrangement that is perfectly visible since only one LED lights at a time.
• The power supply must be able to provide a current up to 100mA/200mA.
• Frequency of sound indicated on LED display.

We are a trusted Manufacturer and Supplier of Sound Indicator in India. All of us know it is impossible to separate sound effect and light effect. But this simple circuit makes it possible to vary the effect from simple to complex. This circuit is a sort of running light whose rate of change depends on the frequency and intensity of the sound.
About the Circuit :

• The circuit is build around two counter ICs, IC1 and IC2 as shown in the circuit diagram. The sound signals generated are received by condenser microphone. These signals are amplified by pre-amplifier circuit designed around transistor T1. It should be noted that the amplified level must be high enough to overcome the switching threshold of the counter, while its frequency determines how often counter is clocked. After amplification, the signal is applied to IC1 via P1, which controls the sensitivity of the circuit.
• Since audio frequencies are too high for making a good visual effect, the signal frequency is scaled down by IC1 when S1 connects pin11 with pin15 of IC1, when the switch is in other position, pin2 is connected with pin15, the counter then divides by 1 and the effect assumes a completely different character that no longer resembles a running light.
• The actual running light is provided by IC2, a counter with integral 1 from 10 decoder, which is clocked by the Q0 output at pin3 of IC1 of the ten output of IC2 each of which is connected to an LED, there is always one ‘high’. The ten LED have a common bias resistor R5, an arrangement that is perfectly visible since only one LED lights at a time.
• The power supply must be able to provide a current up to 100mA/200mA.
• Frequency of sound indicated on LED display.