Calibratable S-meter with LED bar display
This S meter with LED bar graph can be connected to almost any receiver or transceiver. The threshold of illumination can be set separately for each light-emitting diode, so that the S-meter can be precisely calibrated independently of the characteristic of the S-meter voltage. An additional block with another LM324 Quad-OP and four additional LEDs would extend the range of nine-plus values (e.g. 9 + 5dB, 9 + 10dB, 9 + 15dB, 9 + 20dB, 9 + 30dB, 9+ 40dB and 9 + 50dB).
The circuit board layout shown enables the problem-free construction of the circuit shown with 12 LEDs. With two boards an even finer graduated S-meter with intermediate value display can be set up.