The microcontroller IC is a device that looks like a common IC. But inside it, the virtual a miniature computer. This device can be used instead of transistors and IC older those.
40 years ago Electronics fields used the transistors and ICs were equipment important the various circuit assemblie. but current dividend may become a memory. with the substitution of these microcontroller ICs..
The microcontrollers are also khow as Single computer chip, that smallest. Inside consists of central processing unit, Clock signal unit, input-output unit to connect external devices.
Today, we can find microcontrollers have around us. They are used in appliances such as washing machines, microwave ovens, cell phones, printers, video recording, cameras, even in the car was also involved with the micro controller.
This ICs used is the number MC68HC705K1 manufactured by Motorola. Which it is ICs that cheaper, suitable for amateurs to experimentation and use study the performance of the micro-controller.
In the circuit as figure 1 has working as follows, inside IC1 will has The memory containing the program according to the needs of the user. For this training contains of the timer program there are two level are set 60 seconds and 90 seconds. Display a count down to 1 second.
– The power supply set are IC3, C2
– The parts for the oscillators frequency circuit are C1,R2,R3.
-The input device used to input data are switch S1(A) and switch-S2 (B).
Two output device to send the information out there is two Section are:
-The sound generator Section are BZ1, Q3, R6,R7.
-The display numeric Section has IC2, LED 7 segment 2 set, Q1,Q2,R4 and R5
Simple timer code
The detail parts.
1. 4.7K Resistors ¼ W 5%___________4 pcs.
2. 100 ohm Resistors ¼ w 5%________1 pcs.
3. 9.1K Resistors ¼ w 1%___________1 pcs.
4. 27K Resistors ¼ w 1%____________1 pcs.
5. 10 microfarad electrolytic capacitors__1 pcs.
6. 0.1 microfarad ceramic capacitors____1 pcs.
7. 100 picofarad ceramic capacitors
8. BC547_____45V 100mA NPN Transistor __1 pcs.
9. IC- LM2936__Ultra-Low Quiescent Current LDO Voltage Regulator
11. MC14511___BCD–to–seven segment latch/decoder/driver IC
12. LED 7 Segment______________________2 pcs
13. Press Switch_________see text_________2 pcs.