Circuits & Schematics: 10 - 2

11. Another PWM controls a switching voltage regulator
    Christopher Paul
    Circuits Supply Texas Instruments SN74LVC2G14 SN74LVC14A TLV333
    .. 220 µV (370 µV with a 3.0-V supply.) The filter settles to much less than that 12-bit ½ LSB voltage in 10 ms and has a peak (not peak-peak) ripple of less than 50 µV. R4 and R5 should be chosen so that the intended ...
    May 20, 2025

12. Revealing the infrasonic underworld cheaply. Part 2 - Hearing the infrasound
    Nick Cornford
    Circuits Analogue Design Audio Oscillators ON Semiconductor LM385
    .. otherwise be up to 200 mV at the output of A4. C1, at 100n, is enough to hold A1 stable during calibration, but it is C2 10 µF that defines the low 3-dB point of A1’s circuit, once allowance has been made for the reduction in its ...
    May 20, 2025

13. Revealing the infrasonic underworld cheaply. Part 1 - Seeking a solution
    Nick Cornford
    Circuits Analogue Design Audio Oscillators Microchip MCP6002 MCP6022 MCP6024
    .. with tear-down pictures, can be found here ( Ref. 2 ). The capsules I had to hand were very similar to those shown, being 10 mm in diameter by 6 mm high. Some experiments to check their frequency response practical details later showed a ...
    May 20, 2025
14. A simple circuit to let you characterize JFETs more accurately
    Cor van Rij
    Circuits Analogue Design Measurement Texas Instruments TL071A
    .. output stage is added. Please note that the output is not short-circuit proof. If preferred, a simple 1 kΩ to 10 kΩ resistor can be added in series with the output. With the current resistor values in the circuit, a ...
    May 15, 2025
15. Circuit delivers constant power to a load
    Kiril Karagiozov
    Circuits Supply Texas Instruments NE555
    .. The trigger input is biased above the trip point by divider R1 R2. Triggering pulses pass through a small capacitor, C1 (2-10 pF), in order to prevent saturation of the comparator (see 8.3.1 of the datasheet). The maximum operating frequency ...
    Apr 29, 2025
16. LM4041 voltage regulator impersonates precision current source
    Stephen Woodward
    Circuits Supply Analog Devices LM4041
    .. control of I S . I S = D amps, where D = PWM duty factor. The asterisked resistors should be 1% or better. Incoming 5-Vpp, 10-kHz PWM causes Q2 to switch R5, creating a variable average resistance = R5/D. Thanks to the 2.5-V Z1 reference, the ...
    Apr 27, 2025
17. Reduce EMI by sweeping a power supply's frequency
    John Betten
    Circuits Supply Texas Instruments TL331 UCC3813N-0
    .. 1 dBµA) shows the before-and-after effects of adding the frequency-shifting oscillator. This design easily achieves a 10-dBµA reduction with a 12-kHz sweep window. A wider window further reduces EMI, but the modulator frequency may ...
    Apr 22, 2025
18. A negative current source with PWM input and LM337 output
    Stephen Woodward
    Circuits Analogue Design Supply ON Semiconductor LM337
    .. rail tolerance. The asterisked resistors are 1% or better and R S = 1.25 Ω. The PWM frequency, F PWM , is assumed to be 10 kHz or thereabouts, if it isn’t, scale C 1 and C 3 appropriately with: and, The resulting 5-Vpp PWM switching ...
    Apr 18, 2025
19. Water-leak detector uses 9V batteries
    Yongping Xia
    Circuits Measurement Analog Devices MAX934
    .. a portable water-leak detector that uses a common 9 V battery for power (Figure 1). The circuit consumes less than 10 uA during detection mode, and a 9 V alkaline battery has greater-than-500-mAhr capacitance. So one battery can last ...
    Apr 18, 2025
20. Digital potentiometers enable programmable biquadratic filter
    Deborah Mancuso Donald Schelle
    Circuits Signal Processing, Filters Maxim MAX437
    .. produces lowpass and bandpass responses, and the addition of a fourth op amp produces a highpass response. Removing R 10 and adjusting various component values produce a notch or bandstop response or an allpass response. Materials on the ...
    Apr 17, 2025

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