Circuits & Schematics: power supply - 9

81. A two-wire temperature transmitter using an RTD sensor
    Jayapal Ramalingam
    Circuits Analogue Design Measurement Texas Instruments INA122 LM334 XTR116U CD40106B
    .. A 24-V DC supply is fed from the control room, and the current drawn is proportional to the temperature. Since the power and signal travel in the same pair of wires, this arrangement offers cable savings. In Figure 1’s ...
    Jun 11, 2025

82. Build a simple, soft-action muting switch
    John Firestone
    Circuits Audio ON Semiconductor 2N3819
    .. circuit in Figure 1 adds a soft muting switch with power-up/power-down muting to a line-level audio circuit. R 4 , C 1 , and JFET Q 1 quietly ground a signal in 100 to ...
    .. audio circuits. For this process to work, the signal path should remain stable to below roughly one-third the normal supply voltages below 4 V in this example. Q 1 can then finish muting. Making Q 1 a more tightly defined PN4392 can ...
    Jun 4, 2025
83. Solar power MPPT control Li-ion battery charger
    Manoj Kumar
    Circuits Supply Solar Consonance CN3165
    .. /constant voltage linear charger for single cell Li-ion and Li Polymer batteries. The device contains an on-chip power MOSFET and eliminates the need for the external sense resistor and blocking diode. An on-chip adaptive cell can ...
    .. diode. An on-chip adaptive cell can adjust charging current automatically based on the output capability of input power supply, so CN3165 is ideally suited for solar powered systems. Thermal feedback regulates the charge current to ...
    Jun 4, 2025
84. Revisited: Three discretes suffice to interface PWM to switching regulators
    Stephen Woodward
    Circuits Supply Microcontrollers Usage Texas Instruments TPS62933
    .. components: the PWM switch Q1, and the ripple filter capacitors C1 and C2. Note that V OUT will go to for about 6 ms during power up while C1 and C2 are charging, but that should be okay. The C2 capacitance required for 1 lsb (0.4%) PWM ...
    .. on this lengthy number shortly. A cool feature of this simple topology is that, unlike many other schemes for digital power supply control, only the precision of R1, R2, and the regulator’s internal voltage reference matter for ...
    Jun 2, 2025
85. A single op-amp solution to stabilize laser output
    Anirban Chatterjee
    Circuits Laser Microcontrollers Usage Texas Instruments OPA551
    .. are often packaged with a photodiode. The output current from this photodiode can be monitored to regulate the output power intensity of the laser diode. SLDs, however, are prone to pathological drifts, such as temperature variations ...
    May 29, 2025
86. Precision programmable current sink
    Stephen Woodward
    Circuits Analogue Design Supply Diodes TL431
    .. constant sink current of: It also illustrates adding a booster transistor Q1 to accommodate applications needing current or power beyond Z1’s modest TO92ish limits. Notice that Z1’s accuracy will be unimpaired because whatever ...
    .. small digital testing system. Be sure to adequately heatsink Q1. Figure 6. The combined current sink and small system power supply where the max I S is 1 A, Max V S is 20 V, and I S = D. Reference Woodward, Stephen. Cancel PWM DAC ripple ...
    May 22, 2025
87. Another PWM controls a switching voltage regulator
    Christopher Paul
    Circuits Supply Texas Instruments SN74LVC2G14 SN74LVC14A TLV333
    .. (µPs) that can produce a PWM clocked at 20 MHz. However, the supply currents running through that IC’s power supply bonding wires can cause voltage drops. This means that the PWM signals don’t quite swing to the ...
    May 20, 2025
88. Converting square-waves into saw-teeth
    Stephen Woodward
    Circuits Oscillators Texas Instruments CD74HC4053 TLV2371
    .. ramp followed by a quick reset to zero) from digital timing signals is a common function. It usually requires a negative supply as sketched in Figure 1, where Negative current through R1 ramps up inverting integrator A1’s output ...
    May 12, 2025
89. Circuit delivers constant power to a load
    Kiril Karagiozov
    Circuits Supply Texas Instruments NE555
    .. you have a load with a variable or poorly specified resistance and want to regulate the power applied to it (a heater for example), merely controlling the voltage or current will not work, as in both cases ...
    .. voltage of the capacitor can be made to oscillate around a midpoint above ground. This design was used to construct a power supply for a thermally driven MEMS. Appendix Figure 3 shows a circuit where a capacitor is charged from a potential ...
    Apr 29, 2025
90. Another simple flip ON flop OFF circuit
    Jayapal Ramalingam
    Circuits Supply Texas Instruments CD4024B CD40106B
    .. to bulkier ON/OFF switches for DC circuits. The circuit has a fairly simple explanation. U1 is a counter. During power on, R2/C2 resets the counter to zero. When you push PB momentarily once, a pulse is generated and shaped by a ...
    Apr 28, 2025

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