Archive for the ‘Audio’ Category
PC (Audio) Signal Generator Using RS232 Port
Using an RS232 port, we can generate square wave oscillation when transmitting data, and this can be “misused” as signal generator (square wave generator). This is a PC Signal generator produce a square wave in audible frequency range. This circuit utilize a transmission of a “U” character from ASCII character set. This character has binary …[Read More]
Tremolo Effect Circuit for Electric Guitar or Other Musical Instruments
Tremolo circuit is a kind of sound effect. We can see this type of effect is applied in guitar effect pedals. Tremolo effect is produced if we modulate the amplitude of an audio signal. The shape of modulating signal can vary from square wave, sawtooth, or sine. When we use a square wave, then the …[Read More]
This simple circuit can be used to drive two high-impedance loudspeakers or stereo phones, taking monophonic input (one channel), to produce a stereo signal which spread along the midway between loudspeakers when the input signal contain many frequency components. This circuit has two channels, left and right, right channel has high-pass active filter and left …[Read More]
Loud 10-W Car Alarm Siren
By generating square-wave output that sweeps down and up in frequency, this circuit can produce force field of high-intensity sound inside car. This circuit can make a car thieve panics and decide to run before anyone catch his action. D1, C1 and R1 produce triangle waveform by shaping a square wave output of IC1. If …[Read More]
Telephone Circuit: Music On Hold
Waiting a call hold can be boring if there is only silence on the line. It’s a good thing to present an “easy music” in call hold, make a long waiting time feels much shorter. This simple circuit (consists of diodes, SCR, and some passive components) allows to place the caller on hold in one …[Read More]
60-dB Range Compressor For Audio
A compressor circuit shown in the schematic diagram below can produce consistent output of 1.4V P-P over entire 60dB range that is very useful for audio level/volume stabilization. As the main components, this circuit uses a 741 opamp and JFET. With input range of 20mV to 2oV, this circuit has delay time of 0.4s (decay …[Read More]
Voltage-Controlled Attenuator (Volume Control) Using FET
Using the circuit shown in the schematic diagram below, we can control the low-level audio signals with ±3V variable DC voltage. This attenuator circuit uses a field effect transistor (FET) to shunt the signal to ground. The R2 is used to control the output level (the attenuation level), but you can use other source of …[Read More]
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