12V


Low-Voltage Cutout For 12V SLA Batteries

This simple circuit protects an SLA battery from over-discharge by disconnecting the load when the terminal voltage drops below a preset level. In operation, a sample of the battery voltage is derived from the 22kΩ resistor and 20kΩ trimpot divider. This is applied to the non-inverting input (pin 3) of IC1, where it is compared […]


12/24/48 V D.C. Tester

The present tester is intended primarily for testing the 24 V electrical circuits found on most pleasure craft. However, if the resistors are given different values, the circuit may, of course, be used for other voltage ranges. For 12 V, the value of the resistors should be 1.2 k?, and for 48 V, 4.7 k?. […]



Low Power 12V Transformerless Power Supply

Many circuits can be powered directly from the mains with the aid of a series capacitor (C1). The disadvantage of this approach is that usually only one half cycle of the mains wave-form can be used to produce a DC voltage. An obvious solution is to use a bridge rectifier to perform full-wave rectification, which […]


Low Power 12V Transformerless Power Supply

Many circuits can be powered directly from the mains with the aid of a series capacitor (C1). The disadvantage of this approach is that usually only one half cycle of the mains wave-form can be used to produce a DC voltage. An obvious solution is to use a bridge rectifier to perform full-wave rectification, which […]


Power Supply For USB Devices

More and more equipment is sold that runs off internal rechargeable batteries. Although a matching charger is usually supplied in the package, there are also devices that can only be charged via a USB port. That is not surprising in the case of USB MP3 players, which have to ‘dock’ in the PC anyway for […]


Power Supply For USB Devices

More and more equipment is sold that runs off internal rechargeable batteries. Although a matching charger is usually supplied in the package, there are also devices that can only be charged via a USB port. That is not surprising in the case of USB MP3 players, which have to ‘dock’ in the PC anyway for […]


LED Mood Light

Introduction: This circuit makes a nice lamp that consumes little power, runs cool, and has an incredibly long lifetime. The lamp puts out a warm yellow shade of light, the color may be adjusted by changing the number of red or green LED strings. Specifications: Operating Voltage: 12V DC Operating Current: 80ma approx. Theory: The […]


Circuit Project:12v Light / Dark Switch

Often, for certain low voltage lighting systems; you would like to turn off the lights during the bright light of the day. Most commercial day/night switches are designed for AC lighting. This hobby circuit below was designed for a 12v DC system. But, it could be modified for other voltage as well. It uses an […]


12 Volt DC Fluorescent Lamp Driver

A number of people have been unable to find the transformer needed for the Black Light project, so I looked around to see if I could find a fluorescent lamp driver that does not require any special components. I finally found one in Electronics Now. Here it is. It uses a normal 120 to 6V […]