Circuits & Schematics: power supply

1. Single switch controls sequential operation of multiple power supplies
   Jayapal Ramalingam
   Circuits Supply Texas Instruments LM393
   .. circuits manage multi-PSU powerup and shutdown sequences In projects containing digital and/or analog circuits, multiple power supplies are used, generally 5 V DC for digital circuits and 15 V DC for analog circuits. Some projects also ...
   .. 5 V DC for digital circuits and 15 V DC for analog circuits. Some projects also use 24 V or 48 V DC as the third power supply. In many cases, these power supplies need to be switched on in sequence, commonly 5 V DC first and 15 V DC ...
   May 12, 2026

2. Piezoelectric tap switch
   David A. Johnson
   Circuits Supply Digital Texas Instruments CD4013
   .. box, as a finger tap sensor. With each tap of a finger to the box holding the wafer, the circuit turns on and off AC or DC power to an external device. The circuit is powered by a 9 V battery and drives a single coil 5 V latching relay with ...
   May 7, 2026
3. Infrared remote control decoder & switcher using Arduino
   Hesam Moshiri
   Circuits Arduino Wireless Atmel ATtiny85
   .. programming of the microcontroller, please disconnect the programmer and restart the board (disconnect and re-connect the power). Then you can store the desired remote control keys (by pressing and holding the SW1). You can change any of ...
   .. to reduce the noise. FB1 and C11 block the input noise peaks. IC2 is the TS2937CW-5.0 regulator that prepares a fixed +5 V supply for the U1 and IC1. D8 indicates good supply provision and C8 and C9 have been used to reduce the ...
   May 7, 2026
4. ΔV_BE thermometer outputs 1 mV/°C without calibration or op amps
   Stephen Woodward
   Circuits Analogue Design Measurement NXP 74HC4053
   .. Some of my best friends are op amps. They embrace such a wide range of varied capabilities, including low noise, high power, micropower, zero-drift, RRIO, high speed, etc., that they’re easy to love. They tend to make analog ...
   .. This precision voltage reference converts Kelvin to Celsius. Speaking of variations that don’t spoil accuracy, the V+ supply, for example, can vary from 5 to 6 volts without affecting accuracy. Output impedance is roughly 2k, so ...
   May 7, 2026
5. I built a 100W stereo class-D amplifier using TPA3221
   Sagar Saini
   Circuits Audio Amplifiers Texas Instruments TPA3221
   .. a cliff. I want to drive my TPA3221 amplifier directly from the car battery in this case. So that it can actually push real power into real speakers, with clean audio and proper engineering behind it. The goal was simple: a compact, ...
   .. 4 ohms. 108 dB SNR which is better than most commercial amplifiers in this power class. 90% efficiency at full load. Wide supply range: 7 V to 30 V on PVDD. Built-in protections: undervoltage lockout, overcurrent and overtemperature. ...
   May 6, 2026
6. BJT is accurate sensor for absolute temperature in Kelvin and Rankine
   Stephen Woodward
   Circuits Analogue Design Measurement NXP 74HC4053
   .. and therefore on only the precision of R1 and R2. No other reference is required or relevant and any 2N3904 will do. The V+ supply, for example, can vary from 3 to 6 volts without affecting accuracy. Passive output impedance is roughly 10k. ...
   Apr 30, 2026
7. Battery switch
   Lapo Pieri
   Circuits Supply Texas Instruments LM5050-1 LM5050-2 CSD17501Q5A
   .. it chooses the one to connect to the load based on the voltage measured at their poles. It can also be used to switch DC power supplies. The growing demand for portable devices capable of working where there is no power grid or it is not ...
   .. 3 A. Figure 1. Generators with load. However, even without a load (as shown in Fig. 2), we can already notice that V 2 will supply V 1 with a voltage of: Therefore a good amount of the energy is wasted on the internal resistors of the ...
   Apr 28, 2026
8. Linearly variable two-wire loop current generator
   Jayapal Ramalingam
   Circuits Measurement Interfaces Texas Instruments LM124
   .. the current, and either LOAD1 (source) or LOAD2 (sink) can be connected. How does the circuit work? First connect a 24 V DC supply, a DC ammeter and a load resistor say, 200 ohms at the source or sink side. In field applications, this ...
   Apr 24, 2026
9. Tiny continuity tester
   David Johnson-Davies
   Circuits Measurement Microcontrollers Usage Microchip ATtiny202
   .. AVR processor from the ATtiny 0-series range, the ATtiny202, which is easier to program by UPDI and has a slightly lower power consumption. I've used a slightly larger battery, the CR1025, and a battery holder which gives a more ...
   .. pin AIN0 is higher than the voltage on the negative pin AIN1, the Analog Comparator output, ACO, is set. Assuming a 3 V supply, the voltage at AIN1 is held at 3 V by the pullup resistor, and the voltage at AIN0 is held at 3 mV by the ...
   Apr 16, 2026
10. Newer, shinier DMM RTDs. Part 2
    Nick Cornford
    Circuits Measurement Analog Devices OP177
    .. a passive network because thermal drifts and mismatches are no longer a problem. LED1 acts both as a rail-splitter and a power indicator, while LED2 gives a simple low-battery warning. The calculated error curve assumes perfect components ...
    Apr 8, 2026

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