This is simple MAX038 generator. It produces sine, triangle and square waves from 1Hz up to 22MHz. The amplitude, offset and duty cycle are adjustable to offer wide range of generated signals.
Frequency adjustment is made as a rotary switch S8 with a capacitor bank and variable resistor P7. Amplitude, offset and duty-cycle are performed via variable resistors. Switch S5 selects generated waveform. The output at U1-19 is 2V p-p for all waveforms. For amplitude adjustment, P6 and R38 form a voltage divider. The summing amplifier multiplies that voltage, so the signal at the output will vary up tp 24.4V p-p. The offset voltage is controlled by resistor P5. Duty-cycle adjustment is controlled by resistror P4.