Circuits & Schematics Fairchild - 4

31. Pocket white-LED torch is power efficient
    Circuits Supply Light Fairchild BC559
    This Design Idea describes a single white-LED torch, which can be housed in an empty glue-stick tube and has a long rechargeable-battery life. The circuit is constructed with just a few commonly available parts. This torch has proven to be highly ...
    Nov 3, 2020
32. Flash an LED from ac-mains power
    T A Babu
    Circuits Supply Light Fairchild LM317
    TA Babu EDN LED technology is opening the door to a variety of high-power-illumination applications. The circuit in Figure 1 can let you know when ac power is available. To drive a power LED from the ac line requires a converter or a similar ...
    Jul 26, 2020

33. Scalable latch requires no capacitors or clock
    Robert Most
    Circuits Analogue Design Fairchild BF256C
    Circuits that latch one-of-N switches usually use a digital approach. Such circuits are often useful in human-interface situations, such as audio-mixing consoles, video-feed selection, or current-loop-control redundancy systems. In high-precision ...
    Feb 18, 2020
34. Linear Regulator=Low-Cost DC/DC Converter
    Susanne Nell
    Circuits Supply Power Fairchild LM7805 BD242
    The circuit in Figure 1 is a good choice if you need a power supply with high efficiency and you don't want to use expensive dc/dc-converter ICs. The heart of the circuit is IC 1 , the common, inexpensive LM7805 linear regulator. The external ...
    Feb 1, 2017
35. AC line powers microcontroller-based fan-speed regulator
    Abel Raynus
    Circuits Supply Microcontrollers Usage Fairchild MOC3021M
    A microcontroller requires dc operating power in the 2 to 5.5 V range, an amount that a battery or a secondary power source can easily supply. However, in certain situations, a microcontroller-based product must operate directly from a 120 or 220 ...
    Jan 19, 2017
36. Inverted bipolar transistor doubles as a signal clamp
    Circuits Analogue Design Radio Fairchild 2N3904
    Art Hogrefe EDN A number of circuits, such as level detectors and AM demodulators, benefit from a rectifier with a low offset voltage. Silicon diodes have an offset of approximately 0.6 V and do not work well in low-level circuitry. A Schottky ...
    Dec 14, 2016
37. Isolated supply powers DVM module
    Circuits Measurement Supply Fairchild FOD2741C KSD1621STF MMBT5087
    Richard Dunipace EDN Low-cost DVM (digital-voltmeter) modules are economical and can significantly reduce design time for instrumentation. Yet, these modules also involve a significant number of design challenges. For example, their inputs are not ...
    Dec 2, 2016
38. Build your own bypass-capacitor tester
    Circuits Analogue Design Measurement Fairchild PN2222A 2N3904 2N3906
    Carl Pugh EDN Most circuits use bypass capacitors and can deliver substandard performance if the capacitors have poor pulse characteristics. Few if any articles cover how to test bypass capacitors for pulse characteristics. The circuit in Figure 1 ...
    Dec 1, 2016
39. Configurable logic gates' Schmitt inputs make versatile monostables
    Glen Chenier
    Circuits Digital Fairchild NC7SZ57 NC7SZ58
    You can assemble a pulse-generation circuit from a simple Schmitt-input AND gate plus a resistor-capacitor timing network. However, if you need a logic function that's not a standard catalog item, you need a Schmitt-input gate or inverter and ...
    Aug 24, 2016
40. Simplified white-LED flasher operates from one cell
    Anthony Smith
    Circuits Supply Light Fairchild NC7SV57
    The white-LED flasher in Figure 1 offers an alternative approach to a previously published idea ( Reference 1 ). Targeting use in portable appliances and products powered by a single cell, this circuit flashes an LED to provide a highly visible ...
    Jun 23, 2016

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