Circuits & Schematics: Design - 4

31. A precision digital rheostat
    Stephen Woodward
    Circuits Analogue Design Supply Microchip MCP4131
    .. tolerance. These limitations conspire to make Dpots a difficult medium for implementing precision rheostats. Recent EDN design idea (DI) articles have addressed these issues with a variety of strategies and topologies: Op-amp wipes out ...
    Feb 25, 2025

32. Tracking preregulator boosts efficiency of PWM power DAC
    Stephen Woodward
    Circuits Supply Fairchild LM317 2N3906
    .. design idea revisits another: “PWM power DAC incorporates an LM317” ( Ref. 1 ). Like the earlier ...
    Feb 17, 2025

33. 1-A, 20-V, PWM-controlled current source
    Stephen Woodward
    Circuits Supply ON Semiconductor LM337
    .. design idea (DI) takes an unusual path to a power-handling DAC by merging an upside-down LM337 regulator with a ...
    Feb 7, 2025
34. Metal detector uses single IC
    Rachel Hageman Steve Hageman
    Circuits Measurement National Semiconductor LM389
    .. input capacitors, or approximately 2 nF) of the Q 1 oscillator determine the frequency of the search oscillator. In this design, the frequency is approximately 370 kHz. For years, this frequency has prevailed in metal detectors, because ...
    Feb 5, 2025
35. How to collect free energy from atmosphere
    Swagatam Majumdar
    Circuits Bad Prescriptions Supply
    .. µF/25 V electrolytic Improving the free energy device The following more comprehensive free energy deriving circuit design was forwarded to me by one of interested readers of this blog Mr. Prashanth Dhonde (Figure 2). Figure 2. ...
    Jan 15, 2025
36. PWM power DAC incorporates an LM317
    Stephen Woodward
    Circuits Supply Fairchild LM317
    .. of the conventional approach of backing up a DAC with an amplifier to boost output, this design idea charts a less traveled by path to power. It integrates an LM317 positive regulator with a simple 8-bit ...
    Jan 14, 2025
37. Capture 16-bit readings of 8 thermistors in less than 1 second for $2
    Stephen Woodward
    Circuits Measurement Signal Processing, Filters Texas Instruments CD74HC4051 CD74HC4053
    .. uncomplicated, inexpensive, and fairly fast (1 MHz), low power voltage to frequency converter (VFC) “Voltage inverter design idea transmogrifies into a 1 MHz VFC” ( Ref. 2 ). See Figure 2. Figure 2. Modified voltage inverter ...
    Jan 14, 2025
38. An ultra low distortion oscillator with THD below -140 dB
    Vojtech Janásek
    Circuits Oscillators Measurement National Semiconductor LME49710
    .. 3 , R 4 , C 1 , C 2 , and C 3 , forms a band-pass filter that sets the oscillator’s resonant frequency to 2 kHz. The design uses a Wien bridge with values R, C, R/2, and 2C because it the oscillator needs an inverting gain of 1. ...
    Jan 10, 2025
39. Current mirror drives multiple LEDs from a low supply voltage
    Rex Niven
    Circuits Supply Light Nexperia BC817
    .. hotter than the others, its gain increases, and it takes more current and gets even hotter until it self-destructs. This Design Idea shows how you can avoid this problem for pulsed-current-mirror applications. Figure 1. A pulsed-current ...
    Jan 6, 2025
40. Ultrasonic mist maker (DIY)
    T.K. Hareendran
    Circuits Analogue Design Oscillators Texas Instruments NE555P
    .. that I was working on. I found lots of ideas on the internet, but they all lacked in one area or another, so I decided to design one. The following lays out my easy-to-build ultrasonic mist maker. It works fine and is, by far, the easiest ...
    Dec 24, 2024

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