Circuits & Schematics: frequency - 2

11. Circuit delivers constant power to a load
    Kiril Karagiozov
    Circuits Supply Texas Instruments NE555
    .. let us generate pulses with constant energy E PULSE , independent of the resistance of the load R L . Then by changing the frequency f of the pulses we can conveniently and precisely control the load power (P = f E PULSE ), from 0 to a ...
    Apr 29, 2025

12. LM4041 voltage regulator impersonates precision current source
    Stephen Woodward
    Circuits Supply Analog Devices LM4041
    .. The C1 and C2 values shown are scaled for F PWM = 10 kHz to provide an 8-bit settling time of 6 ms. If a different PWM frequency is used, scale both capacitors by 10 kHz/FPWM. A hot topic is that Q4 can be called on to dissipate ...
    Apr 27, 2025

13. Reduce EMI by sweeping a power supply's frequency
    John Betten
    Circuits Supply Texas Instruments TL331 UCC3813N-0
    .. the noise, the greater the size, expense, and difficulty of the filter design. Power supplies that operate at a fixed frequency have their largest EMI emission at this fundamental, fixed frequency. Emissions also occur at multiples ...
    Apr 22, 2025
14. A negative current source with PWM input and LM337 output
    Stephen Woodward
    Circuits Analogue Design Supply ON Semiconductor LM337
    .. accuracy is insensitive to supply 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 ...
    Apr 18, 2025
15. Water-leak detector uses 9V batteries
    Yongping Xia
    Circuits Measurement Analog Devices MAX934
    .. which lets you use a smaller value for C 2 . R 10 and R 11 increase IC 1D ’s hysteresis to improve the sound frequency's stability. All capacitors are ceramic, ensuring low leakage current. Reference Tregre, Jeff, ...
    Apr 18, 2025
16. Digital potentiometers enable programmable biquadratic filter
    Deborah Mancuso Donald Schelle
    Circuits Signal Processing, Filters Maxim MAX437
    .. the filter parameters. The biquadratic, or biquad, filter is an exception, however. You can change that filter's corner frequency (ω 0 ), Q, and gain (H) by adjusting the values of three resistors. For that purpose, the lowpass ...
    Apr 17, 2025
17. PWM-programmed LM317 constant current source
    Stephen Woodward
    Circuits Supply Fairchild LM317
    .. source with a novel LM317 topology. The asterisked resistors are 1% or better and R S = 1.25 Ω. The 5-Vpp PWM input has a frequency (F PWM ) assumed to be 10 kHz or thereabouts. If it doesn’t, scale C 1 appropriately with: The ...
    Apr 16, 2025
18. 100-MHz VFC with TBH current pump
    Stephen Woodward
    Circuits Measurement Texas Instruments CD74AC14 CD74AC74 CD74AC161 SN74LVC1G14 TLV9161
    .. analog designer and author Jim Williams published an awesome design in 1986 for a 100-MHz voltage to frequency converter ( Ref. 1 ). He named this high-climber (picture it on the roof of the Empire State building ...
    Mar 25, 2025
19. Can a free running LMC555 VCO discharge its timing cap to zero?
    Stephen Woodward
    Circuits Analogue Design Oscillators Texas Instruments LMC555
    .. design techniques for audio VCOs that have an exponential (a.k.a. linear in pitch) relationship between control voltage and frequency. Great work Nick! I became particularly interested in the topic during a lively discussion (typical of ...
    Mar 24, 2025
20. Use current-mirror biasing to avoid squegging in RF oscillators
    Madhu Siddalingaiah
    Circuits Oscillators Texas Instruments LM3046
    .. Sometimes called motor boating, squegging causes oscillators to start and stop at frequencies much lower than the frequency of interest. Viewed on an oscilloscope, squegging looks like bursts of oscillations. On a spectrum ...
    Mar 11, 2025

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