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40 Segment LED S-Meter

40 Segment LED S-Meter40 Segment LED S-Meter Circuit

Provide your radio with a actual cord signal, again acclimatize the HIGH LEVEL pot to the beginning of anecdotic the aftermost LED (all LEDs on). Remove the arresting completely, again acclimatize the LOW LEVEL pot to the beginning of no LEDs illuminated.

If your radio's S-meter achievement is greater than 5 volts, you mau ambition to alter the HIGH LEVEL pot with a 10K resistor, and accommodate pin 6 of the right-most 3914 with the cathode of a 6.1 volt zener diode, pulled up to 13 volts with a 1K resistor. The anode should be affiliated to ground. You may use a college voltage zener if necessary.

This agreement provides 10ma per LED segment. Change the ethics to the resistors and pots to change the drive accepted to the LEDs. R1=12.5/I R2=25/I R3=37.5/I R4=50/I area I = the adapted LED current