This project is provided as a `prototyping project` as no PC board has been produced. The photographs show the project built on a matrix board using surface-mount components and very fine wire.
The final design will require a double-sided board with plate-through holes, especially for the matrix of LEDs, but for the moment you can refer to the photographs and construct the circuit yourself.
Don't be put off by the appearance of the circuit. It is really just a duplication of a very simple circuit driving a LED that can be built on a matrix board with 0.1` spacing. Most of the surface-mount components can be positioned so the legs will reach a solder-land and you won't need a special surface-mount board.
Click here to download the full size of the above Circuit.
The voltage on the PIC chip is critical and the author had some random faults develop on the screen when the voltage dropped below 4.5v. As soon as any unusual fault develops, the first thing to do is check (replace) the batteries. The author also had a problem with the PIC chip when the supply was above 5.6v (in another project).
The circuit looks very complex but it consists of just two chips, 105 LEDs, a set of driver (buffer) transistors and 6 tactile switches. All the transistors and resistors seem to disappear when surface-mount components are used and the whole project can be constructed on matrix board or on a double-sided plate-through hole PC board. The 4017 is a "decade counter" and this means it has 10 outputs, starting with output pin 3, only one output is HIGH at a time. The 10th output is pin 11 and then the counter starts at pin 3.
The program starts by clocking the 4017 until pin 9 is HIGH. This pin is connected to the input of the PIC chip and the program now knows the state of the 4017.
This is called SYNCHRONISING. See more on this below.
The '628 has two ports, Port A and Port B. Port A has 7 output lines (plus one input-only line) and Port B has 8 output lines. This creates our 15 lines for the screen. The screen is laid out as 15 LEDs "across" and 7 LEDs "down." The data (or information) is fed in at the top of the screen from the PIC chip to the 15 LEDs and the LEDs are connected to the 0v...
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.....
characters left: