Digital Sawtooth Generator

This simple circuit employs an NE555 timer configured as an oscillator, a 7493 counter chain, and a DAC0806 digital-to-analog converter. The output from the counter is fed into the DAC, resulting in a linearly increasing voltage that drives an operational amplifier and a DC-level insertion circuit. The clock frequency should be set to 256 times the intended sawtooth output frequency.

The circuit operates by utilizing the NE555 timer in astable mode to generate a clock signal. The frequency of this clock signal is critical, as it determines the rate at which the 7493 counter advances its count. The 7493 is a 4-bit binary counter that produces a series of output pulses corresponding to its count value. Each output pulse from the counter is connected to the input of the DAC0806, which converts the digital count into an analog voltage.

The DAC0806 is a precision digital-to-analog converter that provides a linear output voltage based on the digital input it receives. As the counter increments, the DAC outputs a voltage that increases linearly over time, producing a ramp signal suitable for various applications, including waveform generation and signal modulation.

The output voltage from the DAC is then amplified by an operational amplifier (op-amp). The op-amp can be configured to adjust the gain of the output signal, enabling further manipulation of the voltage level as required by the application. Additionally, a DC-level insertion circuit can be included to shift the baseline of the output voltage, allowing for customization of the output signal's characteristics.

Overall, this circuit is effective for generating a sawtooth waveform, with the frequency of the output waveform being directly related to the clock frequency set by the NE555 timer. The requirement for the clock frequency to be 256 times the desired sawtooth frequency ensures that the output waveform is stable and meets the necessary specifications for applications that require precise timing and waveform generation. This straightforward circuit uses an NE555 timer as an oscillator, a 7493 counter chain and a DAC0806 D/A conver ter. The counter output feeds the DAC, producing a linearly increasing voltage, which drives an op amp and a dc-level insertion circuit. The clock frequency must be 256 times the desired sawtooth output frequency. 🔗 External reference