Here’s bringing 11 more circuit designs, to experiment, try and enjoy. Happy making!
Atithya Amaresh
In mains-powered equipment, exposed metal parts are connected to earth wire in order to prevent users from contact with high voltages if electrical insulation fails. Connections to ground through earth connection also limit the build-up of static electricity when handling electrostatic-sensitive devices. Earth in a mains electrical wiring system is a conductor that provides a low-impedance path to the earth to prevent hazardous voltages from appearing on equipment and hence the name.
This lamp circuit using ultra-bright white LEDs provides sufficient light for reading purposes while consuming approximately 3 watts of power. In the case of AC mains failure, the battery backup circuit instantly lights up the LEDs. When the power resumes, the battery supply is automatically disconnected and the lamp circuit again works off AC mains.
Efficiency of a solar charging system depends on the weather conditions. Usually the solar panel gets four to five hours of bright sunlight in a day. If the weather is cloudy or rainy, it affects the charging process and the battery does not attain full charge. This simple hybrid solar charger can solve the problem as it can charge the battery using both solar power as well as AC mains supply.
4. 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, who usually press the doorbell switch to confirm that there is no one at home. By turning on the porchlight, the circuit will trick them into believing that someone is inside the home.
Frequency modulation is used in radio broadcast in the 88-108MHz VHF band. This bandwidth range is marked as FM on the band scales of radio receivers, and the devices that are able to receive such signals are called FM receivers. The FM radio transmitter has a 200kHz wide channel. The maximum audio frequency transmitted in FM is 15 kHz as compared to 4.5 kHz in AM.
6. Intruder Detector Using Laser Torch
Here is a simple, low-cost intruder detector that uses an invisible laser beam to detect the intruder. The laser beam is produced using a 3V DC or 4.5V DC laser pointer or torch that is available in the market. The 3V DC or 4.5V DC power supply for the laser transmitter can also be given using a bridger ectifier or full-wave rectifier.
This alarm plays your prerecorded voice message. It is built around the readily available quartz clock. Take the buzzer out of the quartz clock and connect its positive terminal to pin 1 and negative terminal to pin 2 of optocoupler IC MCT2E (IC2). Pin 4 of IC2 is grounded and pin 5 is connected to trigger pin 2 of monostable multivibrator IC 555 (IC3).
Here is a low-cost circuit that automatically extracts solder fumes while you assemble a circuit, thereby saving you from inhaling the same. The solder paste gives off toxic fumes, which could pose a potential health hazard if not controlled. Those working closely with electronic components are at a higher risk of fumes being inhaled.
9. Simple Touch-Sensitive Switch
This touch-sensitive switch is built around NAND gate IC CD4011 and transistor BC547.
10. Efficient LED Blinking for Embedded Systems
Smart hardware design can simplify the embedded software and make it more reliable. Designers use blinking LED signals to indicate different status and for inbuilt testability. Making an LED array blink requires an individual software loop for each LED or an individual timer and specific software to serve it. This can be an issue in a system that uses low-level MCUs which provide limited resources.
Presented here is a simple locker security alarm that can be used to protect a locker from unauthorised access. The circuit is low-cost and forms a fool-proof alarm that receives its control signal from a standard reed switch. The circuit works off a 12V DC power supply.
The Author is a Senior Correspondent with EFY.
