Flashing Eyes


Posted on Feb 6, 2014

This circuit was purposely designed as a funny Halloween gadget. It should be placed to the rear of a badge or pin bearing a typical Halloween character image, e. g. a pumpkin, skull, black cat, witch, ghost etc. Two LEDs are fixed in place of the eyes of the character and will shine more or less brightly following the rhythm of the music or speech


Flashing Eyes
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picked-up from surroundings by a small microphone. Two transistors provide the necessary amplification and drive the LEDs. Any general purpose, small signal transistor can be used for Q1 and Q2, but please note that R3 could require adjustment, depending on the gain of Q1. For medium gain transistors, the suggested value should do the job. High gain transistors will require a lower value for R3, i. e. about 390 - 470 Ohm. You can substitute R3 with a 1K Trimmer in order to set precisely the threshold of the circuit. We aim to transmit more information by carrying articles. Please send us an E-mail to wanghuali@hqew. net within 15 days if we are involved in the problems of article content, copyright or other problems. We will delete it soon.




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