I was planning to buy a function generator, but those things are too expensive so I decided to build one myself. I based my design on a project from "EPE Electronics". The output from this design can't deliver much current, so I'm going to build a amplifier that can drive a 50 Ohm load.
Today I made the output amplifier.
The voltage regulators:
The transformer (2x 15V):
Opamps + cmos switch:
I couldn’t find a 50 Ohm 5W resistor to put in series with the output. Luckily my supplier came with the idea to use 2 100 ohm resistors in parallel.
The L165 opamp I used turned out to be too slow, so I made a new pcb with different opamps. This time I used 2x THS3112.
Yes, the voltage regulators are not mounted straight .
Because I had no 7909 I used a 7905 with a 4.7V zener, this way I get -9,7V.
This pcb is not tested yet, so I don't know if it works.
Since the last update a lot of changes happened to this project. I decided to post it when it was completely ready. I had some problems with it so that’s why it took so long before it was posted here.
At first the circuit wouldn’t work, then I found out that I've forgotten a resistor. After I mounted the resistor, the opamp became very hot and burned out. Probably because of oscillation. I replaced it with a opa2677 and the problems are gone.
The new pcb:
I will not release this pcb layout because there are lots of bugs in it.