ElectroMech Lab

Material required for the circuit: IC 555                                                - 1 No. IC 4017                                              - 1 No. IN4001 Diode                                    - 10 Nos. Red LED 5mm                                   - 6 Nos. Resistor 1K/0.250W                          - 7 Nos. Resistor 100 Ohm/0.250W                - 1 Nos. Variable resistor                                 - 1 No. Disk capacitor 100nF                        - 1 No. Electrolytic Capacitor 22uF/25V      - 1 No. Battery 9V                                         - 1 No. Breadboard                                        - 1 No. Wires for connection as required. 555 timer is working as an astable multivibrator which supplies clocks to Counter IC 4017. And on each clock its output gets high, one after one and repeat this sequence till it gets input clock. Make the connections according to the circuit diagram and play with this very simple and easy

Sometimes we need to control or drive a high voltage and heavy current load by a small voltage signal. For example, if you want to control water motor with your microcontroller output. We know that microcontroller gives only 5v output which is not sufficient to drive a heavy motor. This circuit, about which this post is, is very-very useful for electronics engineer and hobbyist. So pay attention! For this circuit the material we need is… General Purpose PCB - 5x5 cm. Transistor KN 2222A (TO-92) - 1 No. Relay 5V – 1 No. 1K/0.250W – 2 Nos. 10K/0.250W – 1 No. IN4007 – 2 Nos. LED 3mm – 1 No. Connector – 4 Nos. Few wires. Tools. Concept: Weak signal triggers the transistor and transistor acts as a switch for the relay. You can use any relay of 12V, 24V, 5V etc. but we have to consider power supply or battery we will use. Since 5V power supply is easily available and 9V battery can also be used for 5V output (after using 7805 regulator if needed).

How to calculate through-hole resistors value? In Electronics, resistors play a vital role in any circuit. Lot of resistances is used in a big circuit. Before using the resistor we should be aware of calculation of their values and tolerance. So in this post, I am going to teach you how to calculate the value of resistors. I will take example of through-hole resistors having color band over their body. You must have seen such resistors. The resistor given below is Four-colour band resistor. First one is Brown. Second one is Green. Third one is Orange. And Fourth one, at the most right place, is Gold. Its value is 15 Kohm with tolerance 5%. Tolerance means its value can be between 14.25 and 15.75 Kohm. Digit Value: There is a Value chart for each colour according to their position. Value of black colour for 1 st digit is Nil. Value of black colour for 1 st , 2 nd and 3 rd digit is 0.