With this circuit, you can record your voice and play back the same for 20 seconds. The voice recorder circuit is ideal for door phones, automatic answering devices etc. APR 9301 is used in the circuit which is a data storage and retrieval IC without any micro controller programming. The IC requires minimum components…
Ultra Wide Band Technology
Ultra wide band is a carrier free base band technology used in wireless communications especially in Radar applications. It can provide high data transfer in multi-user network. The technology uses the carrier free band without RF carrier to prevent signal interferences. The technology is highly reliable since it has very high resolution within centimeters. It…
Picnic Lamp (White LED Lamp)
This simple White LED lamp switches on when its surroundings turn dark. It is an ideal portable lamp in picnic sites. It uses solar energy for charging the battery and an LDR for automatic switching. 6 Volt 100 mA solar panel is used to charge the battery during day light. During day time, the…
Smart Capacitor power supply
This capacitor power supply can deliver 12 volt DC and 100 mA current to power low current devices. It is provided with surge protection and is totally isolated from mains supply using two capacitors in the phase and neutral lines. So the connected device is safe even if the phase and neutral lines changes. …
Dental curing light
Dental curing light is used by the dentists for treating tooth cavity or filling root canal. The therapy involves the targeted action of high intensity light such as UV light to generate heat by concentrating light in the target area. To fill the cavity of tooth, adhesive chemicals such as polymer resin is used which…
Sealed Maintenance Free (SMF) Batteries
Sealed Maintenance Free batteries are widely used where minimal maintenance and space requirements are the main considerations. In UPS systems, it is used because of its maintenance free and eco friendly features. SMF batteries do not require water and acid top up and are totally maintenance free. There is no water loss during the charge-…
Smart Vibration Sensor
Here a simple Vibration sensor to protect door or window. It generates a loud beep when somebody tries to break the door or window. The alarm stops automatically after three minutes. The circuit uses a piezo element as the vibration sensor. Piezo buzzer exploits the piezoelectric property of the piezo electric crystals. The piezoelectric…
Digital TV Technology
In contrast to the ordinary TV, Digital TV or DTV uses the transmission in Digital format. Digital TV supports various types of picture formats of different combination size and interlacing. The digital format may be High Definition TV (HDTV) or Standard Definition TV (SDTV). HDTV transmission is in p720 (720 Progressive scanning) or i1080 (1080…
Siren Generator
UM 3561 is an excellent Siren generator IC widely used in Toy applications and Surveillance systems to generate different tones. It a ROM (Read Only Memory) IC which can be operated in 2 pen cells and it functions normally down to 2.4 volts. Using only a few components, it is very easy to construct a…
Interactive White Board
Interactive white board is an interactive display device that displays the computer screen that can be controlled using the electronic pen. It is also known as Smart Board. A projector, projects the computer screen on to the interactive board so that the user can control the PC by touching the surface of the board. It…
Code Reading Lamp
Here is a dual colour lamp to read the code printed on the Transistors and ICs. The code and number printed on the black coloured body of these components are difficult to read if the room light is low since the printing is in faint colour or as impressions. This LED lamp is useful to…
Electronic Circuit Breaker
This circuit can sense the overload condition and breaks the power if the load increases above the set point. It is an ideal circuit to protect Uninterrupted Power Supply devices like Inverter.Let us see its working …The Optocoupler MCT2E and the Resistor R3 (1 Ohm 10 Watts) will do the trick. The Optocoupler has an LED and a Phototransistor inside with connecting leads. The LED of MCT2E is connected parallel to the resistor R3 with a current limiter R2 for the LED. The phototransistor of Optocoupler is connected to the transformer derived 9 volt DC through the current limiter R1. The load is connected through the Common and NC contacts of the relay. So it will work normally at power on.
Tristate Battery Level Indicator
Here is a simple but useful battery level indicator to monitor the battery terminal voltage. Efficiency of the battery reflects in its terminal voltage. A good Lead Acid battery will show 13.8 volts in the fully charged state and if it is below 10 volts, the battery needs immediate charging. If the battery voltage goes…
Timer for Charger
Some Microcontroller based Laboratory instruments such as Digital balance, pH Meter etc have rechargeable battery inside. This inbuilt battery should be properly charged for the error free operation of these instruments. If the instrument is not using (or charging) for long time, its inbuilt battery will be destroyed permanently. This charger timer circuit helps to keep…
Clock Controlled Relay
You can switch on a load such as Water pump automatically at the required time through this Clock Controlled Relay. It uses an ordinary clock to trigger the circuit to switch on the load. The load remains on till it is switched off manually. The triggering signal is obtained from the DC voltage that…
Simple Door Alarm
You can use this Simple Alarm to protect the door or Window. It gives a loud beep and switch on the room light when an intruder/burglar attempts to breaks the door lock. The alarm functions only after 5 minutes to confuse the intruder. Working of this burglar alarm circuit is simple. IC1 is used…
Trick to Save a Battery Life
Save your spare batteries from self discharge due to improper charge- discharge cycles. If you forget to charge the sealed lead acid battery for long period, it will not accept full charge during charging and its performance deteriorates. A solar panel can solve the problem and since it charges only during day time, over charging…
Timely Beeper
You can fix this circuit in the switch board that provides power to the loads such as Water heater, Electric Iron etc to remind you that the load is switched on. LED blinks indicating the load on status and the buzzer beeps every 30 minutes. This helps to prevent the wastage of energy usually happens…
Tricks to Protect TV
Here is a simple circuit to protect TV from high voltage spikes during lightning or a power surge in the cable. It can be incorporated in the Coaxial cable of TV Antenna or Set top box. It uses a GDT and Safety capacitor to provide protection from high voltage spikes. The same circuit can also…
Science of Sleep
Sleep is the physiological process by which body gets sufficient rest to rejuvenate the cells including the brain cells. It is actually a shift in brain’s activities to slow the basic bodily functions. This shift in the brain’s activity is accompanied by a major shift in the consciousness. Science of Sleep Sleep can be…