|Note: Q1 & Q2 could be replaced with a single CdS LDR light dependant resistor removed from a bathroom night light.|
Etch your own PC
or use the generic board.
Board size 1.6" x 1.8" (40mm x 45mm)
PDF (168k) <= Etch your board using this file.
|Due to the increase in project e-mail, time wise I am unable to give construction support to this circuit.|
The phototransistors physically mount in the same direction on the etched pc board.
You need a black plastic sleeve around the phototransistors to block the
light coming from the sides. This will make the light exposure more directional
toward the phototransistors front lenses . Thanks
The power consumption of the circuit is extremely low. If you use this circuit to drive a mini amplified computer speaker input the optical circuits "AA" batteries would last years. Use the voltage divider below for a square wave through an amp.
Line out can connect to a larger size speaker directly. If the TLC555 pin 3 output is fed into an amplifier input connect C2 10uf to a 10K resistor in series to a 1K resistor to ground, as a voltage divider. Take your signal from across the 1K resistor and ground. A CdS photo cell taken from a bathroom nightlight can be in series with this output line to the amplifier input used for a crude volume control.
Experiment: To modulate and drive
a super bright LED then replace C2 with a 220 ohm 1/4 watt resistor and
properly attach the +/- LED wires to the line out terminals. Pick up the sound
remotely up to three feet away using a photo-transistor or a optical remote
sensor. This also creates a volume control method.
|C1||.047 uf||1||272-1068||1.29||1||1.29||Pack has two|
|IC Sockets||8 Pin||1||276-1995||0.69||1||0.69||Use a Socket !|
|PC Board||Generic||1||276-159||2.29||1||2.29||Pack has two or use PDF (168k)|
|V1 Battery||4 AA Holder||1||270-409||1.89||1||1.89||Switch in Battery Holder|
|Line Out||PC Board Term.||1||276-1388||2.29||1||xx||Optional Pack of 4|
|Prices as of Sept. 25, 2004||US Dollars||Total||=||14.30||<=Batteries Not Included (-;|