Microcontroller-Based School Timer
The basic requirements of a realtime programmable timer generally used in schools and colleges for sounding the bell on time are:
• Precise time base...
Remotely Programmable RTC Interfaced Microcontroller for Multiple Device Control
This project based on Atmel AT89C52 and Dallas real-time-clock (RTC) chip DS12887 can be used to control and remotely program the switching operation of...
PEAK LEVEL MONITOR
Measurement of peak level is useful while testing an amplifier or a similar device. It is handy while testing a logic circuit, as it...
Solid-State Two-Way Switch
Two-way switches, more profoundly known as staircase switches, are widely used when a load has to be controlled from two ends of the location....
Analogue Capacitance Meter
The principle of operation of this meter is based on pulse-width modulation. Larger the capacitance, higher is the pulse-width and vice-versa. The meter given...
Battery Deep Discharge Saver
This circuit can be used to ensure that a 12V sealed lead-acid battery does not go into the condition of deep discharge. The circuit...
Pulse Rate Meter
Here is a meter to measure the human heart rate. The pulses are picked up around the wrist (just as it is examined by...
Office Monitoring System
This system can be used in offices or hotels to call an attendant from seven different locations. The circuit provides audio indication of the...
Milliohm Meter
Milliohm meter is used to check low resistance of connecting wires. It can deduce the resistance of thick wires, condition of contacts and the...
High-Resistance Meter
This resistance meter can measure resistances up to 200 mega-ohms. The value of the resistance is indicated on a linear meter scale (0-100 uA)....
Nano-Ampere Meter
This circuit can measure currents down into the nano-ampere range. It is useful when building, testing and experimenting with low-power circuits, especially those operating...
BCD Frequency Meter
Here is a simple circuit that precisely measures the frequency in BCD format. The circuit is built around dual comparator LM393 (IC1), dual D-type...
8-bit Generator and Display For Microcontroller
For testing of microcontroller-based circuits, you need two test jigs: One for generating the desired bitstream to serve as the input to the device...
MOVIE MAKER
Like real movies, this circuit makes use of a characteristic of the human eye and brain known as the persistence of vision. A sequence...
Photovoltaic Battery Charge Controller
A charge controller is one of the main components of a solar battery charging system (Fig. 1). Its main function is to fully charge...
ELECTRONIC METRONOME
A metronome is used by musicians for practice in maintaining a consistent tempo, or rubato, around a fixed beat. This circuit produces a regular...
Timer From Old Quartz Clock
You can build an accurate, low-cost timer from the circuit of an old quartz clock. This timer has a time duration of up to...
MOBILE ELECTRONIC WORKBENCH
Typically, implementing and testing even a small circuit requires an elaborate setup that includes breadboards, a dual DC power supply, hookup wires, ICs and...