1966 Mag: Build NE-2 Neon Bulb Computer - scan available

On 28 Jul 2007 at 19:06, Dave McGuire wrote: Those were later, when silicon power diodes got to be cheap. The earlier models had a negative temp coefficient hunk of carbon that actually did a better job of things, rather than lopping off alternate half-cycles. Those diode-in-a-button gizmos were worse than useless. Not only did they cut the power comsumption by *less* than half (cooler tungsten has less resistance), but it shifted the radiated spectrum toward the red something awful, so you got less than half the visible light. You still see something like this in "extra long life" incandescents. Usually rated for somewhere around 135 volts, so running them on 120v resulted in a cooler filament--and orange light. Hopefully, we'll be rid of these things with the proliferation of cheap CFLs. OTOH, RCA during WWII ran extensive advertisements advising running transmitting tubes on 90% rated filament voltage. The claim was made that one could run the tube at nearly full power with greatly increased filament life. Tubes were hard to get unless you were part of the defense effort. Cheers, Chuck