Circuits & Schematics Fairchild - 2

11. Classic 3-leg adjustable regulators have a shunt mode? Who knew?
    Stephen Woodward
    Circuits Supply Fairchild LM317
    When parts have been around as long, and in such widespread use, as the venerable LM317 and LM337 (and their siblings), you tend to think every trick that can be played with them is already in the (data)book. So, when the question arose whether ...
    Jul 24, 2023
12. Transistor boosts regulator current
    Yngve Linder
    Circuits Analogue Design Supply Fairchild LM317
    Some circuits need a constant-current source that does not necessarily connect to a power-supply rail or to ground. The circuit in the Figure 1 shows a simple method for achieving that configuration. Figure 1. The simple method achieves a ...
    Jun 15, 2023

13. "Ultimate" continuity tester hides many tricks up its sleeve
    Louis Vlemincq
    Circuits Measurement Fairchild BC548 BC558
    I was reminded recently of a tester I designed years ago. At the time, I wanted to build “The Ultimate Continuity Tester,” and I established a wish list of all the features I required: A “real continuity” tester. Too many ...
    Jun 7, 2023
14. Adjustable regulator trimmer simple failsafe circuit
    Stephen Woodward
    Circuits Supply Fairchild LM317
    Frequent contributor, Peter Demchenko, recently published “A safe adjustable regulator” ( Ref. 1 ) discussing the likelihood and consequences of rheostat-connected voltage trimmer failure in three-terminal adjustable regulator ( LM317 , ...
    Apr 18, 2023
15. Self-oscillating H bridge lights white LED from one cell
    Luca Bruno
    Circuits Oscillators Supply Light Fairchild BC550 BC557
    You can build a self-oscillating H bridge by replacing the pullup collector resistors of a classical BJT (bipolar-junction-transistor) astable multivibrator with PNP BJTs (Figure 1). Because this circuit oscillates at supply voltages as low as 0.6 ...
    Feb 15, 2023
16. DC/DC converter using transistors
    Mithun K. Das
    Circuits Beginners Supply Fairchild BC547
    Sometimes, you may need to make a DC/DC converter with minor components that can handle small loads. In this article, we are going to make something like that. This DC/DC converter using transistor has only a few components and can handle small ...
    Jan 12, 2023
17. Astable multivibrator lights LED from a single cell
    Luca Bruno
    Circuits Supply Light Fairchild BC550C
    Lighting LEDs from a single 1.5 V cell poses a problem because their forward voltages are higher than the cell’s. The simplest way to light the LED is to use a step-up dc/dc converter. This Design Idea offers a simple and reliable alternative ...
    Dec 23, 2022
18. Circuit adds foldback-current protection
    José María Espí Rafael García-Gil
    Circuits Supply Fairchild LM317
    For many applications that require power-supply currents of a few amperes or less, three-terminal adjustable-output linear voltage regulators, such as LM317 , offer ease of use, low cost, and full on-chip overload protection. The addition of a few ...
    Nov 5, 2021
19. Position detectors provide motor-control logic
    Steve Pomeroy Russell Hedges
    Circuits Power Fairchild H21B1
    In the circuit of Figure 1, assume that a brush-type dc motor must drive a load back and forth between two endpoints on a lead screw. Optical sensors determine end of travel, and an SPDT switch selects to which end to send the load. The sensors ...
    Sep 21, 2021
20. A discrete auto power-off timer with excellent characteristics
    Patrick Van Torre
    Circuits Supply Fairchild BC547
    Over the years, various power-off circuits have been published. However, the circuit proposed here is very simple and has excellent characteristics. It features a fast power-off transition, with only 8 mV voltage drop at power on and sub-µA ...
    Sep 7, 2021

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