If you use a power supply make sure the DC is clean and ripple free. Listen to what you record, it sounds creepy! :Q This will shake the filament slightly and these vibrations will modulate the light output. Connect the output of the solar cell to your mic input on your sound card and record this. Connect it to a battery and shine it on a solar cell. If you want to try something interesting go find an old sealed beam bulb like the ones used in earlier model automobiles (before the halogen days). If a battery light appears to flicker this happens because it's driven by a PWM converter which is often the case because it needs a higher voltage than the battery can produce and/or the builder wanted regulated (constant output) light over the life expectancy of the power cell.
Most drivers will keep them in the near kHz range so the flicker does not become bothersome as well as the possible stroboscopic effect on fast moving objects.Īn LED driven directly from a battery, will have no flicker whatsoever. Many drivers will pulse the LED's to conserve power (or in the case of white LED's) to maintain a more constant tint over their operating brightness range. Thus if connected to a power source that fluctuates one is much more likely to detect aberrations in the incoming power. LED's OTOH, have MUCH faster attack and decay times - the measure of how fast they reach brightness and how fast they go dark respectively. A silicon cell connected to a small amplifier and pointed to a bulb will reveal a hum though. Incandescent lights flicker off 60Hz but due to the attack and decay times of the filament, the AC carrier superimposed is buffered enough that human eyes cannot perceive it.