When I examine function generators, there are a wide range of products. I see products between 7 USD and 600 USD.
If they can do the same job, why is there so much difference in price? I can't make sense of it. I don't think these cheap products can actually produce a sine wave with a negative voltage portion. Maybe they are producing PWM like Arduino (no negative side). For example, in the video below, do it yourself function generator.
I take the function generator to use in diode tests. When I give an AC voltage without disconnecting the diode on the circuit, I will decide whether the diode is solid or not with the oscilloscope.
This is the function generator that I think can generate the AC signal that I intend to buy. I think there are a few good brands such as RIGOL, UNI-T