In this article I will be talking about this device that we call HCPL3120 or also J312, and we see that it is an isolated gate drive opto coupler which we can use for driving H-bridge MOSFET and IGBT gates safely from the low voltage logic side to the high voltage power side. It has […]
Opto
How to Make LED/LDR Opto Coupler
Ever needed an application where the resistance of a resistor needed to vary proportionately in response to a PWM or a varying analog voltage? Yes, this is where an LED-LDR opto-coupler becomes so useful. The following image shows the symbol for a LED LDR opto-coupler. Any other regular opto-coupler, such as an LED/transistor, LED/FET, or […]
How to Switch Two Batteries Manually using Opto Coupler
The following article explaining a dual battery changeover relay circuit was requested by Mr.Raja so that it could become possible to switch between his old and new inverter batteries automatically, eliminating manual interventions. Let’s read it in details. Technical Specifications “I bought a new 12v 110 Ah lead acid battery for the dc home lighting system. I had another 12v […]
How to Connect a Relay through an Opto-Coupler
In the following post I have explained how to drive a relay by using an isolated method, or through an optocoupler device. We will learn three methods, first method is by connecting relay directly with the optocoupler output pins, second method is by using external PNP transistors, and third method is by using external NPN […]