Watchman Watcher

Here is a circuit that can be used in offices, stores, warehouses, etc during night to check whether the watchman of your establishment is on duty. For operation, it uses an...

Low-Cost Electronic Quiz Table

Here is a simple, low-cost quiz table for four game participants. It determines the contestant who first presses the switch (S1 through S4) to answer a question and locks out the...

Highway Alert Signal Lamp

Here is a signal lamp for safe highway driving. The lamp automatically emits brilliant tricolour light when a vehicle approaches the rear side of your vehicle. It emits light for 30...

Doorbell-Controlled Porchlight

This add-on circuit automatically turns on your porchlight when your doorbell rings, so you can see the person ringing the doorbell at the doorstep. This also helps to guard against burglars,...

Intercom with Musical Ringtone

Here’s a low-cost two-way intercom circuit with musical ringtone that can be made using readily available components (see Fig. 1). Melody generator IC UM66 (IC1) generates ringtone for the intercom circuit. The...

Ultra-Bright LED Lamp

This ultra-bright white LED lamp works on 230V AC with minimal power consumption. It can be used to illuminate VU meters, SWR meters, etc. Ultra-bright LEDs available in the market cost...

Mains Manager

Very often we forget to switch off the peripherals like monitor, scanner, and printer while switching off our PC. The problem is that there are separate power switches to turn the...

Solidstate Switch For DC-Operated Gadgets

This solid state DC switch can be assembled using just three transistors and some passive components. It can be used to switch on one gadget while switching off the second gadget...
circuit ebooks

10 Free eBooks On Circuits

From understanding basic circuits to creating complex circuits, from analog to digital circuits, from designing circuits on PCs to circuits analysis, these free ebooks on electronics carries everything that you ever...

Versatile CMOS/ TTL Logic and Clock Probe

For fault diagnosis of any logic circuit, you need a probe that can test the logic level or existence of clock activity. The circuit shown here can be used to test...