Circuits & Schematics: 10 - 3

21. PWM-programmed LM317 constant current source
    Stephen Woodward
    Circuits Supply Fairchild LM317
    .. 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 resulting PWM switching of Q 2 creates a ...
    Apr 16, 2025

22. Infrared (IR) receiver circuit minimizes power consumption
    David Lees Donald Schelle
    Circuits Microcontrollers Usage Fairchild FDN359AN FDS6679 QSE113
    .. you should choose the part-number option according to your application. The maximum data rate (determined by Q1) exceeds 10 kbps. Materials on the topic Datasheet Fairchild FDN359AN Datasheet Fairchild FDS6679 Datasheet Fairchild QSE113 ...
    Apr 15, 2025

23. Test technique quantifies jitter of discrete-comparator design
    Tim Davis
    Circuits Measurement Analog Devices AD8220 ADR5041 LT1634 LT3081 REF195
    .. The crystal clock’s supply is powered with 5 V from the REF195. The clock’s output will swing between 5 and 10 V with respect to ground. The level-shifted clock is applied to the comparator’s inverting terminal. The ...
    Apr 9, 2025
24. Flip ON flop OFF without a flip/flop
    Stephen Woodward
    Circuits Supply Texas Instruments CD4069UB
    .. out that Figure 3 will work. Figure 3. Do something useful with the other 2/3rds of U1, eliminate Q1 for loads of less than 10 mA, and gain short-circuit protection for free. R ON for the 4069 is V+ dependent but can range as low as 200 Ω ...
    Apr 7, 2025
25. A novel approach to creating a high-efficiency, simple buck-boost converter
    Mike Wong Tamara A. Papalias
    Circuits Supply Renesas EL7515
    .. resistor with 1.0 V V GS threshold. It is fully on when the input is below 4.2 V. When the input is greater than 4.2 V, pin 10 of the boost converter needs to rise above the input voltage. Therefore, the voltage divider of R 5 and R 6 begins to ...
    Apr 3, 2025
26. BJT muting switch
    Rod Elliott
    Circuits Audio Fairchild BC549 BC559
    .. increase distortion. Also, be aware that there is a small DC offset when the circuit is on (muting), but at less than 10 mV it can be ignored for the most part, provided the following circuitry is not DC coupled. At worst, it may cause a ...
    Apr 1, 2025
27. A simple, purely analog -130 dB THD sine wave generator
    Christopher Paul
    Circuits Oscillators onsemi NE570 SA571
    .. notch filter. To simulate practical variances from the ideal, capacitor values were randomly selected to be within 1% of 10 nF, and R1 and R2 to be within 0.1% of ideal values for a 2400-Hz F OSC . A value of R3 that produced a 130 dB notch ...
    Mar 7, 2025
28. Three discretes suffice to interface PWM to switching regulators
    Stephen Woodward
    Circuits Supply Microcontrollers Usage Texas Instruments TPS54332
    .. possible where: as D = 0 to 1. Figure 2. Simple circuit for regulator programming with PWM where V OUT ranges from 0.8 V to 10 V as the duty factor (D) goes from 0 to 1. All that’s required to add PWM control to Figure 1 is to split R 2 ...
    Mar 7, 2025
29. Simple setup tests bit-error rate
    Israel Schneiderman
    Circuits Digital Texas Instruments LM393 SN74HC74 SN74HC86
    .. to allow for the delay in the receiver. An exclusive-OR gate produces a sampling pulse at each bit transition typically, 10% of the data-bit width. This sample pulse samples the raw data the receiver generates, producing clean data. Figure ...
    Mar 4, 2025
30. 1 A, 20V PWM DAC current source with tracking preregulator
    Stephen Woodward
    Circuits Supply Microchip MIC2253
    .. generation. The daisy chain of three 1N4001 diodes provides bias for Q2 and Q4. The PWM input frequency is assumed to be 10 kHz or thereabouts. Ripple filtering is the purpose of C1 and C2 and gets some help from an analog subtraction ...
    Mar 4, 2025

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