Circuits & Schematics: power supply - 5

41. 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

42. 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
43. LM555 begets basic bang bang thermostat
    Stephen Woodward
    Circuits Automation Beginners Supply Texas Instruments LM555
    .. action with an NTC thermistor and bias resistor R B as shown, presto! You get a simple but practical thermostat. It turns power (and a substantial amount of it: up to 15 V and 300 mA) ON to the load (e.g., a resistive heater) if the ...
    Apr 6, 2026
44. Is your PLC/DCS reading the field contacts reliably?
    Jayapal Ramalingam
    Circuits Automation Measurement Texas Instruments LM124
    .. and contact closed conditions. Figure 2 shows the interface module housing the above circuitry. You do not need a separate power supply for this module, as it takes power from PLC/DCS. The connection of this module to the field contact and ...
    .. are located in the unit control room, which is at least 100 meters away from the field. Long cables run between them. They supply 24 VDC to these contacts and measure the current through them to determine status, such as open or closed. ...
    Mar 27, 2026
45. 1 MHz 555 VFC
    Stephen Woodward
    Circuits Measurement Texas Instruments LMC555 TLV9051
    .. Here’s how it works. The story begins with Figure 1. Figure 1. Starred components are precision, including the +5 V supply, but something’s missing. There’s nothing novel about the input current source comprising A1, Q1, ...
    Mar 27, 2026
46. 5 decade antilogarithmic PWM current source
    Stephen Woodward
    Circuits Supply Texas Instruments LMC555 LTC2066
    .. sawtooth generator spans 5 decades of frequencies ( Ref. 1 ) 555 VCO revisited ( Ref. 2 ) 5 octave linear(ish)-in-pitch power VCO ( Ref. 3 ) Tune 555 frequency over 4 decades ( Ref. 4 ) Wide-range tunable RC Schmitt trigger oscillator ( ...
    Mar 26, 2026
47. Ultrasonic range finder with RP2040-Zero & LVGL GUI
    Hesam Moshiri
    Circuits Measurement Microcontrollers Usage Waveshare Electronics RP2040-ZERO
    .. with breadboards or other hardware. Programmability: Compatible with C/C++ and MicroPython programming environments. Power supply: Supports a 5 V input through USB or external sources, with an onboard 3.3 V regulator. The Waveshare ...
    Mar 19, 2026
48. DC to DC buck converter [Adjustable, 97% efficient, 3 A]
    Hesam Moshiri
    Circuits Supply MPS MP2315
    .. “The MP2315 is a high frequency synchronous rectified step-down switch-mode converter with built-in internal power MOSFETs. It offers a very compact solution to achieve 3 A continuous output current over a wide input supply ...
    Mar 18, 2026
49. 3V sweeping siren alarm
    David A. Johnson
    Circuits Audio Oscillators Analog Devices LTC1799
    .. which has a resonant frequency of about 2.5 kHz. The result is a siren which is quite loud but draws only 40 mA from a 3 V supply. A piezoelectric device from Kobitone, part number 254-PB515-ROX , shown on the right in Figure 2, (Mouser ...
    Mar 17, 2026
50. An LM317-based 0-20 mA to 4-20 mA 2-wire converter
    Ashutosh Sapre
    Circuits Analogue Design Measurement Interfaces Fairchild LM317
    .. R S and R Z sets the 4 mA “zero” value in the 4-20 mA output loop, set using P Z . This is pulled from the 24-V supply, going from IN to OUT, and into the output loop via R S and R Z . A 20-mA input current creates a 1.25 V drop ...
    Mar 5, 2026

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