Various waveform signal generators

The circuit is as shown in the attached picture, which is composed of a six-inverter digital integrated circuit 74HCU04. It can output three signals of rectangular wave, triangle wave and sine wave at the same time. The signal frequency is continuously adjustable from 10Hz to 1MHz. A to F are six inverters, A and C1 form an integrator, and B, C, R2, and R3 form a Schmidt circuit. When the output signal of the Schmidt circuit is fed back to the input end of the integrator through R1 and RP1 , forming a square wave oscillator. The oscillation frequency can be approximated by the following formula: fosc=1/4 [(R1+RP1)C1](R3/R2). Adjusting RP1 can change fosc. If the minimum oscillation frequency is taken as 1, the oscillation frequency can be continuously adjusted in the range of 1 to 20 times. The relationship between the capacity of C1 and the oscillation frequency fosc is as shown in the attached table.

F, R4, RP2, and R5 form a linear inverting circuit. Use four diodes VD1~VD4 to form a bridge. Limit the top of the triangle wave and convert it into a sine wave. Adjust the value of RP2 to minimize the distortion rate of the sine wave.