led test circuit | Next Electronics

Most PC enclosures provide only a single LED to indicate hard disk access, with the LED being connected to the motherboard via a two-pin connector. However, this LED only works with IDE drives, and if a SCSI disk controller is...

led bicycle lights

Before getting started, an acknowledgment is due. The circuit presented here employs an innovative method of controlling a flyback converter using the voltage developed across a current-sensing resistor. This approach was published by Andrew Armstrong in the July 1992 issue...

Mains Voltage Indicator with a LED

A need exists for a 220V AC line light display or main voltage monitor due to frequent electrical issues in a home. To create a 220V AC line light display or voltage monitor, a circuit can be designed using a combination...

LEDs and resistors circuit

An LED, or Light Emitting Diode, is a semiconductor device that allows current to flow in one direction while blocking it in the opposite direction. This characteristic makes LEDs polarized components, having a positive side known as the anode and...

Pocket LED Light

This is a pocket-sized LED flashlight operating with only one AAA battery. However, the super high luminosity LEDs (blue, green, or white) require at least 3.5 volts of forward voltage. This flashlight is boosting input voltage up to the operating...

AC Line powered LEDs

The circuit below demonstrates how to power one or two LEDs from a 120-volt AC line. It utilizes a capacitor to reduce the voltage and a small resistor to limit the inrush current. As the capacitor needs to allow current...

LED Chaser

I don't know why, but people like blinking lights. You see LED chasers everywhere, in TV shows (Knight Rider), movies, and store windows. This schematic is my version of a simple 10 LED chaser. There is no 555 timer used...

LED current limiter accepts ac or dc

When an application does not require PWM (pulse-width-modulated) dimming or controlled frequency operation, the primary concern may be preventing excessive current that could damage or destroy LEDs. A simple LED current limiter can be created using a common low-dropout linear...

LED or Lamp Pulser

This circuit operates a LED in pulsing mode, i.e. the LED goes from off state, lights up gradually, then dims gradually, etc. This operation mode is obtained by a triangular wave generator formed by two op-amps contained in a very...