We will describe the function of a digital stopwatch, 0 G 99 sec. The function of the stopwatch, relies in the use of 4 integrated circuits, which in this case belong to National Semiconductor ( It is obvious that other integrated circuits can be used to achieve the same result, however in this case we have used the following parts: The circuit that has been used is shown in picture 1.
Click here to download the full size of the above Circuit.
Through the experimental part we will explain each of the parts function, but in order to have a notion of the basic idea, let just say, that this circuit besides the 5V power supply, is fed with a pulse which comes from a crystal. The crystalG ™s pulse is devided properly in order to obtain the 1 Hz pulse which we need in order for the circuit to work properly, and display the seconds on the 7 segment displays, through a procedure which we will explain through the experimental part. We will begin the description of the digital circuit above. For our convenience we will devide the circuit to 2 parts: the generator, which produces the pulse of the desired frequency, and the part that does the actual counting. The generator of the circuit comprises of the integrated circuits CD4040CM and CD4060CM. We use a crystal which oscillates at a frequency of 4, 194, 304MHz. It is obvious that this frequency is completely useless, as it is too big to be used as it is to our circuit. What we should is devide this frequency, in a way that in its final form, the pulse will have a frequency of 1Hz, which is the desirable frequency. Initially we use the integrated CD4060, which devides the imported frequency in its input, by forces of 2. As we can see on the integrated circuit the outputs are marked as Q4, Q5, G Qn. By importing a pulse in the CLK input of the 4060, with a frequency f Hz, we take out of output Qn, a signal which has a...
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: