- #8051 microcontroller proteus library how to#
- #8051 microcontroller proteus library driver#
- #8051 microcontroller proteus library series#
If you are from Nashik you can buy all types of Electronic Components from our shop at Thakker Bazzar, New CBS, Nashik. GST bill will be provided in the name of DNA Solutions (GST No: 27BGPPS9522M1ZF) or ElectroSource Private Limited (GST No: 27AAFCE7605R1Z).ĭNA Solutions is an Online shop for Electronic Components located in Nashik, Maharashtra and delivering Electronic Components all across India. We provide GST Tax Bill for claiming Tax Input Credit.
#8051 microcontroller proteus library series#
Also there is no need of the series base resistor as the IC has an internal resistor of 2.7KΩ These IC’s are high voltage, high current Darlington transistor arrays with open collector outputs and free-wheeling clamping diodes hence there is no need of a diode across the relay.
#8051 microcontroller proteus library how to#
Figure 3 shows how to connect a relay to microcontroller using ULN 2003/ULN 2803. If you want to connect more relays to microcontroller then you can use ULN 2003 for connecting seven relays or ULN 2803 for connecting eight relays. So basically Q2 & R2 acts as an inverter. And when a LOW is applied from the controller the TRANSISTOR Q2 turns OFF so the base of transistor Q1 gets high voltage through the resistor R2 so the transistor Q1 turns ON which turns ON the relay So now when a High is applied from the controller the TRANSISTOR Q2 turns ON so the base of transistor Q1 gets 0 so the transistor Q1 turns OFF so the relay turns OFF.
#8051 microcontroller proteus library driver#
Figure 2 shows the upated Relay Driver Circuit. This may also damage the device connected to relay so as to avoid this problem another transistor Q2 has been added between the controller & the previous transistor. Whenever 8051 microcontroller is turned ON initially the controller is in reset state and all the controller pins are HIGH which would result in TURNING ON the relay every time power is turned ON or if there is a power fluctuation. In practice you require roughly double the value of this current so we will calculate for 1.4ma of base current.īase Current(1.4ma) =o/p current of controller (0.5ma) + 5v/R3įrom the above equation the value of R3 comes out to be 5.55KΩ. The gain (h fe) of BC547 is 100 so we need to provide at least 70ma/100 = 0.7ma of base current. So our BC547 transistor will require enough base current to make sure it remains saturated and provide the necessary collector current i.e. Normally a relay requires a pull in current of 70ma to be turned ON. Hence an external pull up resistor R3 is used. This current is not sufficient to drive the transistor into saturation and turn ON the relay. Hence the maximum output current will be 5v/10k = 0.5ma. 8051 microcontrollershave an internal pull up of 10KΩ. Microcontrollers have internal pull up resistors hence when a port pin is HIGH the output current flows through this internal pull up resistor. When working with 8051 controllers I have noted that it’s not compulsory to use this resistor as the controller has internal 10k resistor which acts as a base resistor. Resistor R2 is used as a Series Base Resistor to set the base current. The resistor R1 defines the current flowing through the LED thereby defining the LED’s intensity. The LED is used to indicate that the RELAY has been turned ON. This diode is also called as free-wheeling diode. Normally 1N4148 diode can be used as it is fast switching diode with a maximum forward current of 300ma. When the transistor is switched OFF the energy stored in the inductor is dissipated through the diode & the internal resistance of the relay coil. A diode (1N4007/1N4148) is connected across the relay coil this is done so as to protect the transistor from damage due to the BACK EMFgenerated in the relay's inductive coil when the transistor is turned OFF. The relay is turned OFF by writing LOGIC 0 on the port pin. The transistor is driven into saturation (turned ON) when a LOGIC 1 is written on the PORT PIN thus turning ON the relay. As you can see an NPN transistor BC547 is being used to control the relay. The function of relay driver circuit is to provide the necessary current (typically 25 to 70ma) to energize the relay coil.įigure 1 shows the basic relay driver circuit. Also some relays with current rating of 30 Ampere are also available. Also relays of various current ratings are available in market most commonly used relays is called as Cube relay with 12V coil and 5 Ampere rating. Generally relay coils are designed to operate from a particular voltage often its 5V or 12V. For a relay to operate a suitable pull-in & holding current should be passed through its coil. Relays are devices which allow low power circuits to switch a relatively high Current/Voltage ON/OFF. Round Shell Connector/Aviation Connector.