In the figure we have a circuit in which two moving bar/dot indicators are connected together to increase the number of LEDs. The circuit is from a Radio Electronics from October 1980.
This circuit was published in a 1981 magazine, but it can be easily assembled using a BC548 paraQ1...
This circuit is from a 1967 publication, but it can be implemented with any Triac of the TIC...
This circuit was found in an 80's EDN. The circuit uses a current common CMOS, the 4093 powering...