tag:blogger.com,1999:blog-7590176649168185428.post8478306681687441769..comments2024-03-27T17:14:31.032-04:00Comments on SolderSmoke Daily News: Science Fair Light Beam Communications in 1960sBill Mearahttp://www.blogger.com/profile/07662500663603350847noreply@blogger.comBlogger1125tag:blogger.com,1999:blog-7590176649168185428.post-70285483498851327142012-10-02T11:12:02.141-04:002012-10-02T11:12:02.141-04:00I also got hooked on light beam experiments after ...I also got hooked on light beam experiments after a visit to the Museum of Science and Industry in Chicago back in the mid 50's. They had a display labeled "music on a light beam" and you could interrupt the beam with your hand to confirm the transmission method. I built a detector using a phototube (probably a 1P40 or similar) from a broken door alarm of the time connected to a home brew one tube preamp and headphones. The transmitter was the bulb and lens from a hand lantern driven by a Heathkit audio amp that was originally built for a guitar amp. I found that the distortion was horrible if the lamp was driven directly from the audio power of the amp, but if it was "biased up" into near normal brightness with DC it sounded pretty good. Later I added a parabolic reflector that I had made for an earlier science fair project to the receive end that gave me at least a few hundred feet "DX" outdoors at night.<br /><br />Paul W2IOGAnonymousnoreply@blogger.com