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
Best Answer
I bought the ultra-cheap function generator last year. It is based on an XR2206 IC clone. It is barely usable. The sine and triangle waves have DC superimposed, you need to add your own cap to remove it (or a bias circuit). the square wave amplitude and duty cycle is fixed. One of the knobs is backwards. The harmonic distortion on the sine is horrible, about 5%. To keep it cheap, they took a lot of shortcuts, they didn't even include the symmetry trim (most users won't be able to set it properly anyway).
I thought that I could get by with it, but I couldn't, I just bought a used HP33120A on ebay.
What do you get for more money:
I am usually pretty good at work-arounds and making due with what I have, but the cheap version is below my threshold. Depending on your needs, it might be usable for you.