Circuits & Schematics Supply - 13

Many graphic (passive/active (TFT)) LCDs require multiple positive and negative supply voltages. At “power on” and “power off,” these bias voltages must be sequenced properly, along with the LCD’s data and control ...

A USB port offers a handy source of 5 V power for auxiliary devices. A USB port not only supplies power to a microcontroller and other essential circuitry, but also provides enough extra current head room to charge a small battery or supercapacitor ...

Although rechargeable batteries offer many advantages, they can suffer damage and shortened service lives if they're fully drained of their charge. The circuit in Figure 1 shuts off a battery-powered appliance in this instance, an LED ...

The circuit in Figure 1 is suited for inductive sources such as a dynamic microphone, transformer or inductance sensor/pick up. Figure 1. A simple amplifier circuit suited for inductive sources such as a dynamic microphone, transformer or ...

For VCRs, TVs, and other equipment that requires a standby mode, you must supply power to a µP when other components are asleep to receive and interpret any wake-up signal from the remote control or from the broadcasting company. These types ...

A few years ago, manufacturers specified their white, but dim, LEDs for a maximum forward-current rating of 20 mA. Today's white LEDs deliver more light and thus must operate at ever-higher bias currents. Maintaining control of an LED's ...

Most inexpensive pushbutton switches, particularly pc-board-mounting and membrane types, have momentary action. Latching types are often larger and relatively expensive, and they frequently are unavailable in the style you'd like to use. You ...

When you face the task of generating a regulated voltage that's higher than the available power-supply voltage, you may consider a boost regulator. Although a boost converter can in theory generate almost any voltage that's higher than its ...

The low-cost, three-transistor boost switching regulator in Figure 1a is a modified astable multivibrator comprising Q 1 , Q 2 , and L 1 , which substitutes as a load for Q 2 . At the full output power of 200 mW, the oscillation frequency is ...

Many LED drivers, using both charge pumps and inductors, are available to boost the 1.2 to 2.4 V available from single- and dual-cell NiMH (nickel-metal-hydride) batteries to the 3.6 V that white LEDs require. However, most of these circuits, such ...