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 is from 1957 Raytheon documentation. The phone must be high impedance with 600 ohms...
Found on a Radio Electronics, but also on other sources and placed elsewhere in this section, this low...
This oscillator produces a signal with a central frequency in 1 MHz. This frequency can be...