mini light

Posted on Feb 5, 2014

The handheld mini light beam receiver. On the left is a small solar cell, you can make out the various components on the circuit board through the transparent lid of the box. On the right, top and bottom, are the headphone and crystal earpiece sockets while the battery is just visible in its holder at the back (far right). I simply unplug the batt

mini light
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ery connector to turn the unit off. A very simple device to convert light into sound can be made by wiring a solar cell directly to headphones (or an earpiece). The solar cell converts light into electricity and the headphones convert electricity into sound. The limitation is that this set-up is very insensitive. What follows is a far more sensitive circuit as it contains a transistor amplifier which provides about x100 amplification. The circuit must rate as the simplest starting point to effectively listen to light! We have made what is effectively a simple preamplifier stage which for example can go before a pair of computer speakers. The circuit is capable of powering a crystal earpiece and (with some loss of volume) stereo walkman MP3 type headphones directly. As only the AC part of the signal goes through to the transistor it does not matter which way round you wire in the solar cell. So with just a handful of components and a battery you can start to re-explore the world with this little device - to hear what you have up to now only seen! 1) find a room with loud music playing (or orchestra playing) and when outside look out for sunlight reflected from one of the windows (or use torch / laser) and listen to the light - can you hear the orchestra on the light !. 3) listen to the dappled light from trees or from the ever changing surface of the sea / lake. Try listening to light shinning through a fan / extractor or...

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