Need a clean negative voltage for your project? Then this 9V negative power supply circuit is a perfect solution which provides low ripple output and stable performance, making it suitable for many DIY electronics applications. This circuit is designed to produce a smooth 9V negative DC supply from AC input which at first, steps down […]
How to Test SCR using LED and 9V Battery Circuit
This article is about simple SCR tester circuit, where we can use this circuit to check SCR is good or faulty. The circuit uses one 9V battery, one LED, three 100 ohm resistors and two push button switches. The circuit is very easy to build as it is also very useful for students, hobby users […]
Simple LDR Based Refrigerator Door Warning Circuit
In our previous post, we designed a Refrigerator Door Open Alarm Circuit with IC 555 but however, in this post, we design a Simple LDR Based Refrigerator Door Warning Circuit without using any IC. Moreover, this circuit helps to alert the user when the fridge door stays open for a long time, as this simple […]
Dual Threshold Voltage Comparator Circuit using IC LM741
A dual limit comparator is an important electronic circuit which compares one input voltage with two fixed voltage levels. In simple words, this Dual Threshold Voltage Comparator Circuit using IC LM741 checks whether the input voltage stays within a fixed range and it also checks whether the voltage crosses the upper limit or the lower […]
Simple AC Mains Presence Indicator Circuit
An Simple AC Mains Presence Indicator Circuit helps us check whether AC mains supply is present at the input and whether power reaches the load side. This circuit is easy, low-cost and very useful for home appliances, control panels, extension boards and industrial systems. In this circuit, two LEDs show two different conditions, first LED1 […]
Three LED Blinking Circuit with NPN Transistors
This article is for Three LED Blinking Circuit with NPN Transistors that uses 3 NPN transistors, resistors, capacitors and a 9V battery, which works as an astable multivibrator, so it does not need any external clock signal. Instead, the circuit creates its own oscillation, because of this, the LEDs alternately flash ON and OFF at […]