1 00:00:00,190 --> 00:00:10,270 Music 2 00:00:10,290 --> 00:00:12,280 Music 3 00:00:12,300 --> 00:00:16,340 Narrator: When you're trying to detect a wavelength of light that our eyes can't see, like infrared 4 00:00:16,360 --> 00:00:20,390 light, you need to use a detector that can tell you that it's there. The simple 5 00:00:20,410 --> 00:00:24,420 circuit we're building here can receive a signal in infrared light and convert into sound. 6 00:00:24,440 --> 00:00:28,480 You'll need a photocell or solarcell with two wire leads, 7 00:00:28,500 --> 00:00:32,520 and audio cable with a headphone jack on one end and 8 00:00:32,540 --> 00:00:36,570 wire leads on the other, two test leads with jumper clips at each end, 9 00:00:36,590 --> 00:00:40,640 and an amplifier/speaker. 10 00:00:40,660 --> 00:00:44,690 We'll star with the photocell. Gently attach one of the jumper 11 00:00:44,710 --> 00:00:48,710 clips onto each of the wires coming from the photocell. 12 00:00:48,730 --> 00:00:52,750 Now do the same with the wires on the audio cable, 13 00:00:52,770 --> 00:00:56,770 clipping the other ends of the leads onto each one. It doesn't 14 00:00:56,790 --> 00:01:00,780 matter which wire you clip each one onto as long as you've made a complete circle. 15 00:01:00,800 --> 00:01:04,830 Now plug the other end of the audio cable into the jack marked 16 00:01:04,850 --> 00:01:08,860 input on the amplifier/speaker. That's it, you've built a circuit that 17 00:01:08,880 --> 00:01:12,910 receives the infrared signal from a source--such as a remote control--and sends 18 00:01:12,930 --> 00:01:16,970 that signal to the amplifier/speaker which turns it into sound. 19 00:01:16,990 --> 00:01:28,218 Music