Electronics Circuit Hub

Opamp Constant Current Source Design In This blog I will explain constant current source design using operational Amplifier. The explanation is also available in Video link given below in the blog. Above is the basic circuit diagram of constant current using opamp. Due to virtual ground concept voltage at inverting terminal is zero. Current flowing through inverting terminal is zero because input terminal of opamp is very high. Assume : Ii = Current flowing the resistance R1 = Input current IL= Current flowing through Variable resistance R3 = Load Current Since No current will flow through opamp inverting terminal and hence Ii = IL Ii = Vin/R1 and hence IL = Vin/R1 So if Vin and R1 is fixed Ii remained constant even if load R3 changes. In spite of changing the load R3 the Ii remained constant.  Application : Opamp constant current source is used in LED droving as per below circuit. The complete explanation can be seen in below video: Thanks !!!

 LT Spice Simulation - 12V Power Supply Design Using Operational Amplifier In This Blog, I will explain the LT Spice Simulation for 12V power supply design using operation amplifier. In last blog we have already seen the design of op-amp series voltage regulator. We have derived the equation for output voltage and understood the working of circuit diagram. So it is highly recommended to read the previous blog before reading this blog. Specifications : Vin = 18V to 24V Vo = 12V Io = 50mA Components used : D1 = 1N750 (4.7V Zener Diode) Op-Amp = LT1368 (Rail to Rail Op-Amp) Q1= BC846C (Ic = 100mA) R1=15.6K R2=10K R3=1K Calculation for Vo : Vo = Vz * {(R1+R2)/R2)}     = 4.7V * {(15.6K+10K)/10K}     = 12.032V BC847C works in a linear region to regulate the output voltage based on the output voltage of error amplifier. BC847C can source up to 100mA current to the load. Complete explanation of LT Spice design & simulation can be seen i...

        LT Spice Simulation - Opamp Monostable                    In This Video LT Spice Design and Simulation shown for Opamp Monostable                   Basic Circuit : LT Spice Circuit : Simulation Results : Thanks !!! Note : This circuit is not tested in production and it is only for educational purpose.