Circuits & Schematics: 10 - 3

21. Advanced sensitive lightning detector with PC graph
    Mirko Pavleski
    Circuits Measurement Fairchild 2N3904
    .. several resistors and capacitors, detecting coil (180 turns on a ferrite core with a diameter of 1 cm and a length of 10 cm), and a rod antenna from an old pocket radio. Now let's see how the device works in real conditions. First, we ...
    May 27, 2026

22. 4/20mA to 0/20mA loop current converter for grounded loads
    Jayapal Ramalingam
    Circuits Analogue Design Measurement Interfaces STMicroelectronics LM124
    .. with 4 mA and 12 mA. Simulation test results are shown in Table 1. Table 1. Simulation test results I IN (mA) 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0 I OUT (mA) 0.44 2.56 5.06 7.56 10.1 12.6 15.1 17.6 20.1 Calculated I OUT (mA) 0 2.5 5.0 ...
    May 25, 2026
23. 30A AC soft starter (inrush current limiter)
    Hesam Moshiri
    Circuits Arduino Supply Microcontrollers Usage Atmel ATtiny13
    .. current limiter) project Designator Qty Description / Value AC-IN, LOAD 2 KF45C-9.5-2P C1, C2, C6 3 100 nF-50 V, X7R 10% 0805 C3 1 1 µF-25 V, X7R 10% 0805 C4 1 470 µF-25 V D10×L10.2 mm C5, C8, C9 3 10 µF-16 V, X5R ...
    May 20, 2026
24. ΔVbe thermometer is switchable between °C and °F
    Stephen Woodward
    Circuits Measurement Texas Instruments CD4073B
    .. between Celsius and Fahrentheit scales. Figure 1. Switch U1a and current mirror Q2Q3 apply an excitation current ratio of 10.23:1 to the 9-sensor transistor string. The string is tapped at 5 × 200 µV/ C = 1 mV/ C and 9 × 111 ...
    May 14, 2026
25. Single switch controls sequential operation of multiple power supplies
    Jayapal Ramalingam
    Circuits Supply Texas Instruments LM393
    Simple analog 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 ...
    May 12, 2026
26. Piezoelectric tap switch
    David A. Johnson
    Circuits Supply Digital Texas Instruments CD4013
    .. 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 a 10 A contact rating. The relay can switch AC or DC power. In standby mode the circuit draws a low 1 µA. A firm ...
    May 7, 2026
27. Infrared remote control decoder & switcher using Arduino
    Hesam Moshiri
    Circuits Arduino Wireless Atmel ATtiny85
    .. record up to three IR codes in the EEPROM memory and switch 3 separate devices. Each relay can handle the currents up to 10 A. The load switching mechanism (momentary ON/OFF, toggling etc) can be programmed by the user. I used Altium ...
    May 7, 2026
28. ΔV_BE thermometer outputs 1 mV/°C without calibration or op amps
    Stephen Woodward
    Circuits Analogue Design Measurement NXP 74HC4053
    .. Figure 1’s circuit does, in fact. Figure 1. Switch U1a and current mirror Q2Q3 apply an excitation current ratio of 10.23:1 to the 5 sensor transistor series array. This creates a 5 × 200 µV/ C = 1 mV/ C AC signal ...
    May 7, 2026
29. I built a 100W stereo class-D amplifier using TPA3221
    Sagar Saini
    Circuits Audio Amplifiers Texas Instruments TPA3221
    .. amplifier. When CMUTE is HIGH, the outputs are muted. Output filter Each half-bridge output gets an LC low-pass filter, a 10 µH inductor followed by filtering capacitors. This reconstructs the audio waveform from the PWM switching ...
    May 6, 2026
30. ΔVbe + DMM = Celsius, Kelvin, Fahrenheit, and Rankine thermometer
    Stephen Woodward
    Circuits Measurement Linear Technology LTC2066
    .. AAs will support 2000 hours (nearly three months) of continuous operation. A single CR2032 lithium coin will hold up for 10 non-stop days. Thanks, Nick and Jim! References Woodward, Stephen. BJT is accurate sensor for absolute temperature in ...
    Apr 30, 2026

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