This circuit found in a 90s Popular Electronics, triggers a huge array of LEDs from the sounds captured by a microphone, thus generating visual effects.
This circuit is from 2005 Linear Technology documentation. The circuit applies to 12 V systems and...
This circuit was originally designed for medical applications and biological experiments. The...
This circuit is from 1977 documentation, but can be assembled with BC548 for Q1, Q2 and Q4, BC558...