Shadow Sensor Alarm
by T.K. Hareendran in Alarms | Lights | Tested |
Shadow sensors are widely used to detect the movement of a person in a confined area. Many circuits published earlier have a serious drawback that only one light dependent resistor (LDR) is used for shadow detection. Needless to say, this is not a perfect solution! Shadow Sensor Circuit Schematic Described here is a simple but...
LED DC Voltage Indicator
by Jim Keith in Measure |
This LED DC voltage indicator circuit is a voltmeter, rather than simply a battery tester. As such it may measure voltages as low as 3V. It utilizes venerable LM741 operational amplifiers applied as comparators that drive LED indicators. Voltage thresholds are 3, 6, 9 and 12V. Above each incremental threshold an additional LED...
Rain Sound Generator – Sleep Aid in Case of Insomnia
by Popescu Marian in DIY | Hobby |
Insomnia treatment consist mostly of sleeping pills consumption but this circuit is an alternative for that and consists of a simple circuitry that generates a rain sound effect. The japanese researches were the first to discover that sound of rain has a relaxing effect. With the help of this simple circuit we can generate the...
Audio Processor Circuit
by Popescu Marian in Audio |
This audio processor circuit features the SSM2045 IC which was developed specially for electronic music applications and the 741 opamp IC. The circuit is configured as a low pass filter with a DC voltage control for gain. The input signal is set to a working level of 150mVpp through the resistor R1. How does the audio...
DIY Digital Thermometer Circuit
by Popescu Marian in DIY | Measure |
This diy digital thermometer circuit can measure temperatures up to 150°C with an accuracy of ±1°C. The temperature is read on a 1V full scale-deflection (FSD) moving-coil voltmeter or digital voltmeter. How the digital thermometer works Operational amplifier IC 741 (IC3) provides a constant flow of current through the...
Sensitive Clap Switch Circuit
by D Mohankumar in Useful |
This is the circuit of a very sensitive clap switch. It switches ON/OFF a White LED or electrical appliances through claps. The circuit can sense the sound of claps from a distance of 1-2 meters. Condenser Mic picks up sound vibrations caused by the clap. These sound vibrations are given to the inverting input (pin2) of IC1....