Posted intech notes
Matching Transistors, 2SC1815 or 2N3904
You need to use well matching transistor pairs to make a good quality transistor ladder VCF. Above is the classic methodology to find matching transistor pairs. I tried this procedure with 2SC1815 and 2N3904 I have. Next version of Analog2.0 boards will support the both types of transistors, so I wanted to know how different they are in VCF perspective. Here is the result: The result shows that 2N3904 has less variability. This comparison might not be fair since my 2SC1815 transistors are very cheap ones purchased from Akizuki-Denshi, so these might have different quality control in manufacturing than usual retail transistors. But at least I learned following: 2N3904 is…
