All Sections Fairchild

1. Current monitor
   Peter Demchenko
   Circuits Fairchild BC560
   Almost every wall power supply has no indicator showing whether current is consumed by the load or not. It seems that this was a shortcoming that was not only noticed by me: I once saw the solution given in Figure 1. Figure 1. Wall power supply ...
   Apr 24, 2025
2. KSD1691 — Datasheet Fairchild
   Datasheets Fairchild KSD1691
   NPN Epitaxial Silicon Transistor
   Apr 23, 2025

3. PWM-programmed LM317 constant current source
   Stephen Woodward
   Circuits Fairchild LM317
   LM317 fans will recognize Figure 1 as the traditional LM317 constant current source topology. It closely regulates I OUT = V ADJ /R S by forcing the OUTPUT pin to be V ADJ = 1.25 V positive relative to the ADJ pin. Thus, I OUT = V ADJ /R S to a ...
   Apr 16, 2025
4. Infrared (IR) receiver circuit minimizes power consumption
   David Lees Donald Schelle
   Circuits Fairchild FDN359AN FDS6679 QSE113
   Receiving infrared (IR) signals while conserving system power is difficult, and typically requires the inclusion of complex power-management routines in the firmware. You can avoid that problem by disconnecting power to the microcontroller when IR ...
   Apr 15, 2025
5. QSE114 — Datasheet Fairchild
   Datasheets Fairchild QSE114
   Plastic Silicon Infrared Phototransistor The QSE113/114 is a silicon phototransistor encapsulated in a wide angle, infrared transparent, black plastic sidelooker package.
   Apr 15, 2025
6. QSE113 — Datasheet Fairchild
   Datasheets Fairchild QSE113
   Plastic Silicon Infrared Phototransistor The QSE113/114 is a silicon phototransistor encapsulated in a wide angle, infrared transparent, black plastic sidelooker package.
   Apr 15, 2025
7. BJT muting switch
   Rod Elliott
   Circuits Fairchild BC549 BC559
   Introduction In general, muting and/or signal switching is done by relays, FETs or CMOS analogue switch ICs. All have limitations, but a little known technique that really doesn't look like it could ever work is to use bipolar transistors. The ...
   Apr 1, 2025
8. Tracking preregulator boosts efficiency of PWM power DAC
   Stephen Woodward
   Circuits Fairchild LM317 2N3906
   This design idea revisits another: “PWM power DAC incorporates an LM317” ( Ref. 1 ). Like the earlier circuit, this one implements a power DAC by integrating an LM317 positive regulator into a mostly passive PWM topology. It exploits ...
   Feb 17, 2025
9. FDC604P — Datasheet Fairchild
   Datasheets Fairchild FDC604P
   P-Channel 1.8V Specified PowerTrench MOSFET This P-Channel 1.8V specified MOSFET uses Fairchild’s low voltage PowerTrench process. It has been optimized for battery power management applications.
   Feb 11, 2025
10. PWM power DAC incorporates an LM317
    Stephen Woodward
    Circuits Fairchild LM317
    Instead 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 PWM DAC topology to obtain a robust ...
    Jan 14, 2025

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