Circuits & Schematics: power supply - 2

11. 5 octave linear(ish)-in-pitch power VCO
    Stephen Woodward
    Circuits Oscillators Microchip MCP602x
    .. months back, frequent DI contributor Nick Cornford showed us some clever circuits using the TDA7052A audio amplifier as a power oscillator. His designs also demonstrate the utility of the 7052’s nifty DC antilog gain control input: ...
    Jan 30, 2026

12. FM receiver/radio using Arduino and TEA5767
    Hesam Moshiri
    Circuits Arduino Microcontrollers Usage Radio TSC TS2937 TS2940
    .. chip. This chip is a 3 W+3 W Hi-Fi Class-D amplifier that can operate with only a single 5 V supply. The maximum output power can be achieved using 4-ohm speakers. According to the datasheet: “The PAM8403 is a 3 W, class-D audio ...
    .. tasks are performed by the Arduino-Nano code. R3, C7, C8, and C9 build a first-order low pass RC filter that reduces the supply noise. R1 and R2 are mandatory pull-up resistors for the I 2 C bus and CON1 is a UFL connector that provides ...
    Jan 22, 2026
13. Combine two TL431 regulators to make versatile current mirror
    Stephen Woodward
    Circuits Analogue Design Supply ON Semiconductor TL431 TLV431 NJW21193G
    .. you must also accommodate the modest heat dissipation limits of these small devices. However, the maximum current (and power) capabilities can be extended virtually without limit by the simple ploy shown in Figure 2. Figure 2. Booster ...
    Jan 22, 2026
14. Ignoring the regulator's reference redux
    Christopher Paul
    Circuits Analogue Design Supply Texas Instruments OPA2383 REF35 SN74AC04 TLV9151
    .. operating point. This is also previously seen in “Improve the accuracy of programmable LM317 and LM337-based power sources” ( Ref. 2 ) and numerous other places. I’ll refer to his DI as “the DI” in ...
    .. and R 2 /R 1B ratios, leaves open the option of using an op amp whose inputs and output needn’t approach its positive supply rail. The (original) DI is a solid design that obtains some dynamic performance benefits from reducing the ...
    Jan 21, 2026
15. Extend the LM358 op-amp family's output voltage range
    Christopher Paul
    Circuits Analogue Design Texas Instruments LM258 LM358
    .. and still have their uses. These parts’ outputs can approach (and for the inputs even include) their negative supply rail voltage. Unfortunately, this is not the case for the positive supply rail. However, cascading the op amp ...
    Jan 18, 2026
16. SCR topology transmogrifies into BJT two-wire precision current source
    Stephen Woodward
    Circuits Supply Fairchild LM317
    .. feedback loop. R3 provides a trickle of current, a few hundred nanoamps, sufficient to jumpstart (trigger?) the loop when power is first applied. To program the source for a chosen output current (I O ). If I O 5 mA, then: R1 = 1.30/I O R2 ...
    Jan 15, 2026
17. Tuneful track-tracing
    Nick Cornford
    Circuits Measurement Printed Circuit Boards (PCB) Microchip MCP6002
    .. amplifying stage feeding a pitch-linear VCO (PLVCO). It also senses when contact has been made, and so draws no power when inactive. Figure 1. A power switch, an amplifying stage with some careful offsets, and a pitch-linear VCO ...
    .. operation while probing different resistances. This type of PLVCO works best with a control voltage centered between the supply rails and swinging by 20% about that datum, giving a bipolar range of ~ 1 octave. Here, we need unipolar ...
    Jan 12, 2026
18. Read isolated digital signals without power drain
    Alfredo Saab
    Circuits Measurement Digital Texas Instruments MAX5048 MAX913
    .. That task is usually accomplished with an optocoupler, but optocouplers have limitations they consume quite a bit of power from the sensing side, they are relatively slow, and the light emitter's aging reduces the current-transfer ...
    .. therefore, forces DATA_OUT high, again copying the state of DATA_IN. IC 1 , IC 2 , and IC 3 operate from a single 5 V power supply. Separate bypass capacitors placed adjacent to each device's power pins minimize noise. Resistors R3 and ...
    Dec 24, 2025
19. Two-wire precision current source with wide current range
    Stephen Woodward
    Circuits Analogue Design Supply Analog Devices LM4041
    .. Figure 1) or a negative (Figure 2) polarity source, but not both from the same circuit. Figure 1. A typical three-wire [power supply (PS), ground, and load] precision positive current source offering an accuracy of 1% or better. The ...
    Dec 18, 2025
20. Buck boost converter using XL6019 (bifilar choke)
    Hesam Moshiri
    Circuits Supply XLSemi XL6019
    .. chip integrates a powerful N-channel MOSFET that can handle up to 5 A of switching current, making it suitable for medium-power applications. The XL6019 includes several built-in features for reliable operation: Soft-start function to ...
    Dec 16, 2025

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