Circuits & Schematics Supply - 15

The circuit in this Design Idea bootstraps a large capacitor in series with the solenoid to provide a large actuation voltage (Figure 1). This higher voltage provides substantially more current to operate the solenoid, speeding the operation of the ...

Portable systems often use LEDs of different colors and in varying quantities of each color. Some examples are white for the display backlight, green for keypad illumination, and red for power. Typically, the LEDs derive power from at least two ...

During the development of systems that include small motors, a simple, bidirectional motor controller with speed adjustment may be helpful. Figure 1 shows such a controller. The circuit uses everyday components whose tolerances and ratings are ...

Many low-dropout-voltage regulators see service in electronic systems, but relatively few are designed for low-noise operation. (For example, Maxim's MAX8887 achieves a noise voltage of approximately 42 µV rms.) However, certain ...

You can improve a current sink's accuracy by at least two orders of magnitude by adding two standard 1%-tolerance resistors. As a bonus, you also compensate for errors that a low-current-gain pass transistor's base current introduces. To do ...

Many people consider white LEDs to be the future of lighting. Strung together, several LEDs can replace an incandescent lamp or a compact fluorescent lamp. High-power white LEDs need a dc voltage of about 3.6 V at a current of about 350 mA to ...

No matter what portable power source you use, the lower the starting voltage your circuitry operates at, the better. A lower startup voltage also maximizes runtime. Furthermore, to completely discharge the power source, circuitry must run on ...

Fellow engineer Sanjay R. Chendvankar of Mumbai, India, recently offered a novel way of reducing current through a relay coil ( see Ref. 1 ). His idea utilized an unused normally closed pair of contacts of that relay to reduce the driving voltage ...

This circuit drives a resistive heater element with a low-frequency, pulse-width-modulation (PWM) voltage source, providing heat output that’s directly and linearly proportional to the duty cycle of the drive signal. The circuit’s ...

Today's digital ICs typically demand complex voltage sequencing, a task that usually requires dedicated ICs or microprocessors. But what if your requirements are more modest? The sequencing scheme presented here requires only a single ...