No. I just wrote 1.00001V to drive the point that it should not be 1.2V or 0.9V but exactly 1V. It doesn't have to be 1.00001V but only 1.01 volt for example. It is enough. With that clarified. I just need a sine wave generator that can produce 1.8V (error of 1.801V) and 5000Hz (not 5001Hz or 4999 Hz). How do you build them anyway? Since I'd rarely use it. My budget for finished product (I want ot avoid building it) is lower to $50..
You're starting to look like a troll to me.
First you have $200 now $50.
First you want 10uV error, then you want 10mV error and now 1mV?
Anyway, the only halfway complete (new) signal generator for $50 that I know of is the FY3200S.
It is what it is. Not nearly what you want, but obviously you don't really know. (Attached an excerpt of the specs for FY3200S)
P.S. At least FY3200S has detailed manufacturer specs, which isn't necessarily a given for $50.
The $200 you guys mentioned are so complex with dozens of functions like square waves and even custom waves. I dont need them I just need sine wave so I think I need single $50 accurate sine wave output only. well. I thought its easy to get 1.0800001V accuracy. But it would be too costly or impossible as you guys say. So I need it to be accurate to 1.80V only, that is good enough. Frequency should be like 3000.0Hz accurate.
It is hard, because the 0.0000001 part of the voltage specified is around 0.1 parts per million. The problem is that kind of accuracy is buried in the noise, and close to the physical limits.
It is not rare to have resistors, capacitors, traces on the PCB, etc, have a variation of more than 10ppm/C, which means that a variation in temperature in your lab of a tenth of a degree would already throw off the accuracy of the voltage supplied, unless you spend thousands on precission components, temperature compensation, and ovenize the whole stuff.
Maybe you could pick a book on basic circuit analysis (Malvino has a very good one) and have a look at the first chapters, which would help you make more reasonable questions. If you write 1.800001V, it is assumed that all digits are significant which, for audio, they are not, and what you need is relative accuracy (in/out), and not absolute, which you implied.
Also, the signal generators on your first post should be able to specify the output voltage. Why do you say you cannot know it?
As per your requirements of a clean sine-wave source for $50 max, I'm not aware of any existing product. You can use your PC soundcard and an amplifier, or probably look on the second hand market. There are usually a lot of older waveform generators for around $50.
Also, if you expect to find a generator in which you set 1.5V and you get 1.5V connecting it to a random multimeter/audio amplifier/oscilloscope/whatever, you will be disappointed. Signal generators are generally specified for an output impedance of 50 Ohms, if you don't match the impedances, the volts out
will not match what you set on the waveform generator's screen. Maybe look around a bit about impedance matching, it might even be the case that the FNIRSI on the first post is actually enough for your needs.