The pins RA3 to RA0, are used as outputs driving each column LED. The pins RB0 to RB7 are used as outputs driving signal for each column LED. The 74HC154 (Decoder 4 to 16) is the chip that decodes the signal into a binary digit dekaexapsifio. In the left figure all the pins of the door at a reasonable RA 0 (Low), in which case only the output 0 of the 74HC154 decoder is logical 0 and the others at logic 1. Therefore only the transistor TR1 conducts and powered on the column of Led connected with it. For what Led by this column will turn determined by the logic state will find the pins RB7-RB0 door RB.
For example, the left shape, because the pins RB0 and RB4 are logical 0 (Low), the Led D1 and D5 will illuminate.
Click here to download the full size of the above Circuit.
The remaining Led the column is connected to pins of door RB will remain extinguished. Also will remain switched off and the remaining Led columns because the transistors that supply them with power do not lead me.
In the figure you can see the Led light up every time, with the combination of the column gate RA, and columns of the door of RB PIC16F84A.
Note that the length of each lighting column with Led is 1 / 16.
If you use an external circuit with registers hold data for each combination, the time of Led Lighting can grow. But the circuit will increase to one in our example is not used.
Note that in each anode Led a resistance limiting current, which is necessary because the Led and protects the feet of the door RB from the disaster.
Timing Circuit
For the timing of the processor used a ceramic filter (Resonator) or 10MHz crystal and two
22pF ceramic capacitors
Feeder circuit
The IC2 stabilize the voltage from 12VDC to 5VDC and capacitors to smooth and filter. If all eight LEDs light up simultaneously, the consumption of the circuit reaches about 90 mA. Stabilizer of the order of 100 mA can be used for security, but use a rate of one Ampere (1A).
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: