Breadboard1 U1 Wire1 Wire2 Wire3 Wire4 Wire5 VCC1 Wire4 Wire5 LED1 Wire8 Wire12 Wire10 R1 Wire13 Wire11 Wire14 Wire15 Wire12 Wire16 Wire9 Wire17 Wire13 R2 Wire18 Wire19 Wire20 Wire14 Wire21 Wire15 Note1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN" "http://www.w3.org/TR/REC-html40/strict.dtd"> <html><head><meta name="qrichtext" content="1" /><style type="text/css"> p, li { white-space: pre-wrap; } </style></head><body style=" font-family:'Sans'; font-size:10pt; font-weight:400; font-style:normal;"> <p style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;">An optocoupler can be used to control a circuit that's completely isolated from your microcontroller in order to avoid the risk of short-circuit. In this case, imagine that the LED + battery pack combo is a hacked toy that you're turning on and off with the Arduino.</p></body></html> Arduino2 PCB2 Wire11 Wire22 Wire23 Wire24 Wire25 Wire26 Wire27 Wire26 Wire27 Wire28 Wire29 Wire31 Wire32 Wire33 Wire34 Wire36 Wire37 Wire38 Wire39 Wire41 Wire42 Wire43 Wire44 Wire46 Wire47 Wire48 Wire49 Wire52 Wire54 Wire55 Wire57 Wire58 Wire59 Wire60 Wire28 Wire29 Wire30 Wire31 Wire32 Wire33 Wire36 Wire37 Wire39 Wire40 Wire41