Circuits & Schematics

Knowing the mains frequency is important in many industries; the speeds of AC motors, for example, are dependent on it. The motor speed is where F is the mains frequency and P is the number of poles. Since P is a fixed number for any motor, speed ...

This 3-wire microphone pre-amplifier in Figure 1 is designed using the low-power, low-noise, and low-distortion OPA1692 audio operational amplifier, making it ideal for high-performance electret microphone applications. The circuit is optimized for ...

This timer circuit draws only 3 µA of current, and can be powered by DC supplies ranging from 3 V to 15 V. The circuit produces accurate pulses whose time can easily be adjusted, based on the R1 × C1 time constant. The time should not ...

This Design Idea enables you to program digital potentiometers with inexpensive rotary incremental encoders. Recent Design Ideas for circuits that manually control digital potentiometers have mostly “revolved” around UP/DOWN pushbutton ...

The USB PD adapter shown in Figure 1 is is a compact variable power supply capable of utilizing nearly any USB Type-C PD power supply with PPS-feature as an input to power your projects with various selectable voltages and high currents. Key ...

Analog circuits have had their day; everything is digital now. However, here’s a simple analog circuit built with one good, old, but still available pulse-width-modulating regulator chip. The automatic DC heater controller circuit introduced ...

A curious connection of control buttons makes a simpler-is-better digital potentiometer interface possible. Two recent submissions to the Design Ideas kitchen (see Related Content) have shown different basic step-per-push pushbutton interfaces for ...

This versatile Design Idea survives and reports open- and short-circuits, not to mention multiplying efficiencies. Generally accepted tech folklore says that after you drive relays and solenoids into full actuation, only half as much coil voltage ...

Using the concept and leveraging the example circuits in this Design Idea, you can divide any frequency by any number divisible by 2. Any dividend frequency can be divided by any number representable by 2 n , resulting in a square wave output ...

The circuit presented here is a 3 W stereo audio amplifier with memory UP/DOWN volume control. The project is based on PAM8408 IC from Diode Incorp which is a filter-less class-D amplifier with high SNR and Differential input which helps eliminate ...