‰ NOW 15 WPM ‰ TEXT IS FROM JANUARY 2016 QST PAGE 43 ‰ LEVEL OF BRIGHTNESS YOU PREFER. ICOM RADIOS PROVIDE 8 V TO THE SM 20 MICROPHONE, SO I SET R5 TO 100 TO SUPPLY A NOMINAL 10 MA OF LED FORWARD CURRENT. R5 CAN BE REPLACED WITH A WIRE JUMPER FOR RADIOS THAT SUPPLY ONLY 5 V. BUILDING THE CIRCUIT THE CHOICE OF COMPONENTS IS NOT CRITICAL. YOU CAN BUILD THE CIRCUIT ON A PIECE PERFBOARD OR ON A PCB LIKE I DID FIGURE 2. THERE IS LIMITED SPACE INSIDE THE SM 20 MICROPHONE. MY PCB MEASURES 1.2 BY 0R73 INCHES AND FITS NICELY INTO A CORNER RIGHT SIDE OF FIGURE 3 OF THE ‰ END OF 15 WPM TEXT ‚