This circuit uses components that are still common despite being from 1995 documentation. The circuit can be powered by 6 to 12 V voltages and the speed of the LEDs' sliding effect is set to P1.
Today we have more compact solutions. This is from a Radio Electronics magazine from October 1990....
This filter was found in Texas Instruments documentation from the 1980s. The circuit uses a common...
16 commercial test circuit for tubes and transistors appeared in Radio Electronics magazine in...