Circuits & Schematics - Supply - 10

With just one leftover op amp or comparator, you can add a battery-condition indicator to your portable circuit design. To indicate the life in an aging battery visually, the circuit in Figure 1 varies the duty cycle and flash rate of an LED when ...

Powering LEDs from a wide dc range say, 30 to 380 V without wasting a lot of power in the regulating block, is a difficult task when the LED current needs to be constant. Dedicated LED drivers are available, but they usually implement boost ...

Surprising facts, like “old fangled” 3-leg linear regulators ( LM317 , LM337 , LM350, et al.) can be used in shunt regulator topologies ( Reference 1 ) can sometimes inspire “new fangled” circuit designs. Figure 1 shows a ...

The purpose of this Design Idea was to improve reliability, add new features, and replace a latching power switch with a momentary one. The features are: The switch has foolproof protection against too frequent switching, which can be harmful for ...

The voltage-doubler circuit in Figure 1 can convert 2.5 V dc to 5 V dc or 1.8 V to 3.3 V. Most voltage doublers use an inductor, but this circuit doesn’t need one. The circuit uses a capacitor, C, by charging it through serially connected ...

Low-cost monolithic precision adjustable voltage references are available in multiple families from multiple manufacturers, but this isn’t true for adjustable precision current references. That’s unfortunate, because while most ...

This switching regulator is highly efficient and can be used for AC and DC and requires no reactive L/C components. The regulator can provide a power factor very close to 1. The circuit (see Figure 1) can be used to regulate a heating process with ...

Many portable appliances and other products that must operate from a single cell are restricted to working at very low voltages. It is thus difficult to drive white LEDs that typically have a forward voltage of 3 to 5 V. The ability to flash the ...

A previous Design Idea describes a programmable current source that used a three-terminal LM317 adjustable regulator (Reference 1). Although that circuit lets you program the output current, the load current flowed through the BCD ...

The accurate, high-side, current-sense circuit in Figure 1 does not use a dedicated, isolated supply voltage, as some schemes do. Only the selected transistors limit the common-mode range. The circuit measures the voltage across a small ...