Hello,
I'm working on a visible light project using a small mirror (3x5-inches) to direct a beam of sunlight to a small telescope with a photo-diode mounted on the eyepiece. Current from the diode is then fed into a small amplified speaker.
Currently I'm using a small DC fan at the mirror/transmitter end of a 650+ foot path to chop/modulate the mirror's light beam and generate an audible tone at roughly 600Hz.
This produces nice loud pulses in the speaker but I would like to get rid of the fan as it blocks too much light. Without the fan I can use a larger mirror and get far greater range.
I need suggestions on a better way (very simple, please) to modulate my photo-diode's ouput current of about 2-3volts. I've been working on this project for a long time and any help is greatly appreciated.
Thanks, Ed KF6DXX!
I'm working on a visible light project using a small mirror (3x5-inches) to direct a beam of sunlight to a small telescope with a photo-diode mounted on the eyepiece. Current from the diode is then fed into a small amplified speaker.
Currently I'm using a small DC fan at the mirror/transmitter end of a 650+ foot path to chop/modulate the mirror's light beam and generate an audible tone at roughly 600Hz.
This produces nice loud pulses in the speaker but I would like to get rid of the fan as it blocks too much light. Without the fan I can use a larger mirror and get far greater range.
I need suggestions on a better way (very simple, please) to modulate my photo-diode's ouput current of about 2-3volts. I've been working on this project for a long time and any help is greatly appreciated.
Thanks, Ed KF6DXX!