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2 Axis Solar Tracker Circuit

The sun trucker uses a combination of three photoresistors R7, R8 and R9, to ensure that the circuit will follow the sun during the day, but stop working at night time. Make this circuit 2 times to have 4 Axis move, by using 2 motors...

Light Alarm

This is a simple Photo-sensing circuit. When light hits the photo-transistor, triggers the 4011 that drives a loudspeaker. Easy to make and can be very usefull too...

Infrared light trap circuit

This infrared light valve has more parts, so it works better and more reliable for alarms. The circuit responds less ambient light. The light valve consists of a transmitter and a receiver. The transmitter consists of a NE 555 which provides pulses to the infrared LED (D1) are fed. The frequency of the pulses is set to P1. On the receiver side we see the photo transistor T1 receives the pulses from D1. The pulses through C4 to the positive input of op amp IC2 led. Between the output of IC2 and the minus input is an RC network that ensures the lowest at about 7.2 kHz amplitude issues. ..

Photo detector using LED

Here's a circuit that takes advantage of the photo-voltaic voltage of an ordinary LED. The LED voltage is buffered by a junction FET transistor and then applied to the inverting input of an op-amp with a gain of about 20. This produces a change of about 5 volts at the output from darkness to bright light. ..

Schmitt Trigger Photo switch

This is basically a Schmitt Trigger circuit which receives input from a cadmium sulfide photo cell and controls a relay that can be used to switch off and on a street lamp at dawn and dusk. I have built the circuit with a 120 ohm/12 volt relay and monitored performance using a lamp dimmer, but did not connect the relay to an outside light. The photo cell should be shielded from the lamp to prevent feedback and is usually mounted above the light on top of a reflector and pointed upward at the sky so the lamp light does not strike the photo cell and switch off the lamp...

Tactile sensors Motor controller

It's basically a photovore with a couple tactile sensors. It's rather complex but can give neat behaviors with modifications to the circuit. At this point I don't have any plans to give more information on this circuit so your on your own. C1 and C2 values C1 and C2 are the capacitors that control how long each motor will reverse after the tactile sensor is triggered. Increasing the value will cause your bot to turn more after bumping an object. Decrease and it will turn less. The layout All resistors are 1M unless labeled otherwise. All capacitors are .22uF unless labeled otherwise. This circuit is more for advanced BEAMers so if your a newbie to BEAM I would recommend the iVore circuit. I may get some more info on the circuit on the web but no plans yet...

Optical switch detector with 555

When the phototransistor is stroken by IR light it conducts and the voltage between the 1Mohm resistor(arbitrary) and the phototrans drops from VCC to lower values. When the voltage drops lower than VCC/3 the 555 is triggered and goes high (from 0 TO VCC). The amount of light that strike the phototrans necessary to bring his collector to VCC/3 is determined by the resistor (Vdrop = Icollector * R , so , if Vdrop= 2*VCC/3, the resistance needed to set the threshold on current is R=2*VCC/(Icollector*3)). ..

Fish Tank Lights and Temperature Detector

When the tank is cleaned the fish are removed and placed in a small amount of the tank water. The problem is that fish don’t like rapid temperature fluctuations. I guess a simple in tank or stick on thermometer would have done the trick but what is the fun in that? If the unit just did temperature monitoring it would have been such a waste of processor capability, so I thought adding colored lighting would be a great addition. Uses 16 high power LED’s, 4 red, 4 green, 4 white and 4 blue. The tube that the LEDs are mounted in is a section of 3/4 inch PVC conduit. LCD Display to display the mode the unit is in and show the temperature. Liquid sealed temperature to read the water temperature. One button to change between modes. Photocell to turn off the lights when there is adequate room light. This is wired and calibrated but this function has been remove to allow the lights to remain on all the time...

Solar powered robot

Make your own solar powered robot at home using things you probably already have. Transistors, resistor, capacitor, solar battery and flashing LED are available at any electronic store, if you don't already have them. Solar cells out of calculators work as well, you might want to use more than one since they are really small. If you do, connect the positive wire from each solar battery together. A small motor should be used like the ones in walkmans. Solder everything together and watch it come alive. Put it under a light and let it charge, it should take couple seconds for each burst of energy. Works best in sunlight...

Light Barrier Detector

This simple circuit using a single transistor turns ON the relay when light falls on the LDR. The potentiometer is adjusted for the required sensitivity. The power supply is 6V. Be careful about the impedance of the relay. Its impedance should not be less that 60ohm. Its working can be explained as follows: With the light falling on the LDR,its resistance is low and the transistor is saturated and turns the relay ON...

Light Detector circuit

This circuit give low level output, when exist enough lighting, that is a detector of light. It can give, say ,command turn on somebodies lights, when fall the dark. His exit is compatible with TTL level and it give low logic level, when phototransistor Q1, detect light. With adjustable resistor RV1, we can regulate the sensitivity that it will have...

Sun - Up Alarm with 4011

The Sun - Up Alarm can be used to provide a audible alarm for when the sun comes up or it can be used in a dark area and detect when a light comes on. It can also be used to detect a light beam, headlights etc. The circuit works as follows. The phototransistor is very sensitive to light. (Any phototransistor will work fine) The sun shining on this device will provide a high to one of the NAND gates. This will cause another NAND gate to oscillate which will drive another gate to output a 100hz tone. The transistor provides drive for the speaker...

Simple Day/Night switch (40106B)

This is a simple circuit that does the day/night switchings you have in mind. POT1 is used to set the light level at which the circuit switches from enable to disable...

Light Switch with 555 Timer

When the phototransistor is stroken by IR light it conducts and the voltage between the 1Mohm resistor(arbitrary) and the phototrans drops from VCC to lower values. When the voltage drops lower than VCC/3 the 555 is triggered and goes high (from 0 TO VCC). The amount of light that strike the phototrans necessary to bring his collector to VCC/3 is determined by the resistor (Vdrop = Icollector * R , so , if Vdrop= 2*VCC/3, the resistance needed to set the threshold on current is R=2*VCC/(Icollector*3)). High sensibility phototrans would need a smaller resistor, and weaker phototransistors higher value resistor, you can also use a trimmer to set the on threshold level with precision. The 555 is proved to be the most versatile and ubiquitous IC all over the world.This is a possible use: simple inverting schmitt trigger...

The sensor has two parts: a transmitter and a detector. They can be placed on opposite sides of your victim's path, or they can both be on the same side using a mirror to reflect the beam back. They should be placed 6 to 12 inches from the floor/ground to prevent their being seen. ..