Circuits & Schematics - Beginners - 3

Vladimir Rentyuk, Zaporozhye, Ukraine A magnet waved past a Hall-effect sensor does the trick This circuit allows you to turn on your holiday bulbs with a wave of the magic wand. The strings flash in sequence. At the heart of the idea is the ...

The following automatic battery-charger design is created with a circuit that could qualify as the simplest window comparator ever built around a single transistor. It starts charging when the battery voltage drops beyond a preset value, and it ...

Use a transimpedance amplifier to drive an LED You can test an IR (infrared) link with a circuit that converts an IR-generated photocurrent to an amplified current that drives a standard LED (Figure 1). This approach provides a visual feedback to ...

The classic Colpitts oscillator circuit in Figure 1 generates a clock signal with a fixed duty cycle. By replacing CMOS inverter gate IC 1A with a voltage comparator (Figure 2), you can obtain a more versatile and more useful clock generator. You ...

Part 1 . Theory Circuit Setup The circuit setup for this experiment is quite simple. You need seven 330 Ω resistors in series with rows R1 through R7 to limit the current through the LEDs. Then the rows are driven by RB0 through RB6 pins of ...

LED dot matrices are very popular means of displaying information as it allows both static and animated text and images. Perhaps, you have encountered them at gas stations displaying the gas prices, or in the public places and alongside highways, ...

The LM317T from National Semiconductor is a popular adjustable-voltage regulator that provides output voltages of 1.25 to 37V with maximum 1.5A current. You can adjust the output voltage with a potentiometer. The circuit in Figure 1 replaces the ...

Voltage-monitoring circuit is based on Microchip 12F675 MCU Lets users set up a tolerance around a specific value A voltage monitor is a common hardware need. But beyond a simple compare, many systems must provide a tolerance around a specific ...

This simple TTL power supply monitor circuit monitors the 5-volt level TTL power line and gives a signal whether the supply voltage is outside or within the necessary range or “window”. The heart of the power supply monitor is a ...

Principle and Working The project of cell charger shown here uses IC( 7808 ) and transistor ( BC547B ). The transformer TR1 is a step down transformer, and steps down 230V AC voltage to 12V AC. This 12V AC is fed to the rectifier bridge. Four ...