IC3 amplifies the sinusoidal signal at point B, after potentiometer P2. In the simplest case, these can be second-order low-pass RC, RC band-pass, LC band-pass, or LC low-pass filters. With a BPF, the central frequency or the resonant frequency should be approximately equal to that of the signal at the same point. The 3-dB frequency of the LPF should be equal to or lower than the frequency of the triangular signal at point A. The quality of that filter determines the quality of the sinusoidal signal, which IC3 amplifies.
It is also routed to the low-pass filter (LPF) or a band-pass filter (BPF). The triangular signal goes to amplifier IC2 via potentiometer P1.
#Audio signal generator generator
The block diagram shows how three low-power audio amplifiers (LM386) are configured to implement a triple-waveform generator at one of two selectable frequencies. The signal in point A is approximately triangular with amplitude of about 0.35 V p-p and a supply rail of +9 V. The simplified block circuit shows IC1 operating as a square-wave generator with frequency determined mainly by R1 and C1 (Fig. As a further convenience, the user can switch the output triplet between two frequencies. The suggested maximum load for each output is 8 Ω, but lower-impedance loads also can be handled with some reduction in output. The generator is useful for checking electrical or audio installations, audio or mains transformers, and similar components. The outputs can be connected to ground, the power supply, or between them for short time without damage. The amplitude of each output can be adjusted independently. This simple, robust, and low-cost signal generator, based on the LM386 power amplifier IC, provides a trio of audio-band signals with three different simultaneous outputs at the same frequency: square/rectangle (SQW), triangle (TRG), and sine (SS).Įach output can drive loads such as long cables, transformers, auto-transformers, audio couplers, or active loudspeakers. This article is part of the Ideas for Design Series: Vol.
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