The Photovore`s brain is built around two NAND-gates and six inverters, four elements each in two 74HC00 IC`s. Two photodiodes (the `eyes`) and two feelers provide input for a Schmitt-trigger, determining which of the two stepping motors (clocks m1 and m2) receives pulses from the oscillator. The feelers have priority over the eyes, and the feeler
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connected to zero has priority over the one connected to plus. So if both feelers touch obstacles, the robot will try to push itself out of trouble. The frequency of the oscillator can be increased with the 5M variable resistor until the seconds hand makes about 17 revolutions per minute. Faster running is possible, but then the stepper will just as easily turn in the wrong direction, which would rob the Photovore of its sense of purpose. The two 47uF capacitors convert the square wave from the oscillator into pulses for the stepping motors in the clocks. Their value depends on the steppers, so 47uF is correct only for the type of clock mentioned in the parts list. Other stepper-driven clocks (not those equipped with a synchronous motor) can be used if you match the capacitor to the load. Ohmic resistance of the stepper coil is a useful guide: At 300 ohms, 47uF was perfect, while a lady`s watch having a resistance of 2K6 needed 4. 7uF (Yes, a Photovore using lady`s watches is possible :) The circuit around the three transistors turns the robot on when the solar panel has charged the capacitor (4700uF) to about 2. 7 volts, and off if the voltage drops below some 2. 2 volts. Use the 250K variable resistor to adjust the switch-off level. You`re OK if the clocks run well until they stop. The diodes and the first BC559 also limit the voltage supplied to the robot to about 4 V. The LED lits up when the limiter is active. If the...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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