Circuits & Schematics

Accurate, inexpensive, and mature platinum resistance temperature detectors (PRTDs) with an operating range extending from the cryogenic to the incendiary are a gold (no! platinum! ) standard for temperature measurement. Similarly, the 4 to 20 mA ...

Boost converters are non-isolated DC-DC converters that step up voltage. In some applications, users expect protection against reverse polarity, short circuits, and other anomalous conditions. The basic PWM boost topology is shown in Figure 1. ...

Conventional astable oscillator circuits that use CMOS logic gates, bipolar transistors or low current op Amps, often require more current than necessary. The circuit shown generates a low frequency square wave signal while drawing only 0.5 ...

Design Idea (DI) contributors have recently explored various possibilities for ON/OFF power control using just a momentary contact “shiny modern push-button,” many of which build off of Nick Cornford’s “To press on or hold ...

Isolated flyback converters usually evoke thoughts-or bitter memories-of custom transformers, slipped delivery schedules, and agency-approval problems. Off-the-shelf flyback transformers carry isolation ratings of only 300 to 500 V and rarely of as ...

To generate high voltages with proper insulation between the “hot node” and the rest of the circuitry, a car ignition coil can function in place of a high-voltage transformer. These coils have voltage ratings of approximately 20 kV, so ...

Professional condenser microphones require a 48-V supply to charge the internal capacitive transducer and power the internal buffer for the high-impedance transducer output. You can use a simple boost converter, a filter circuit to reduce ...

We recently saw how certain audio power amplifiers can be used as oscillators ( Ref. 1 ). This Design Idea shows how those same parts can be used for simple amplitude modulation, which is trickier than it might seem. The relevant device is the ...

LEDs need current to illuminate, and current usually flows through a power supply to an LED. A typical LED-driver circuit uses a transistor to provide current and a series resistor to decrease the voltage you apply to the LED. Unfortunately, the ...

The classical Schmitt trigger circuit that you'll find in textbooks provides some noise immunity, such as for the front end of magnetic pickup in position-sensor circuits (Figure 1a). You adjust the two threshold levels using R 1 and R 2 or R 2 ...