Circuits & Schematics: power supply - 3

21. Adjustable load
    David Johnson-Davies
    Circuits Measurement Supply Microcontrollers Usage Microchip ATtiny84A
    .. adjustable load in Figure 1 provides a constant-current load for testing power supplies and batteries. It allows you to set the load current to up to 1.05 A, using a potentiometer, and ...
    .. ATtiny84 . Figure 1. The Adjustable Load, based on an LT3080 regulator and an ATtiny84A processor, drawing 1 A from a power supply being tested. As well as testing power supplies, the adjustable load can be used for testing rechargeable ...
    Dec 14, 2025

22. A 0-20mA source current to 4-20mA loop current converter
    Jayapal Ramalingam
    Circuits Analogue Design Measurement Interfaces STMicroelectronics LM124
    .. can be multiturn PCB mountable types for precision adjustment. Q1 should have a heatsink. How it works Connect the 24-V power supply, digital ammeter, and a load resistor to J2 as shown in Figure 1. Then, connect a current generator to ...
    .. (DCS) or programmable logic controller (PLC) to monitor, record, and control these process parameters. This equipment will supply 24 VDC to a typical transmitter through one wire and receive current proportional to the process parameter ...
    Dec 5, 2025
23. Gold-plated PWM-control of linear and switching regulators
    Christopher Paul
    Circuits Supply Microcontrollers Usage Texas Instruments OPA2376 SN74AC04
    .. are blameless. To determine U 1 ’s output resistance, its spec shows that its minimum logic high voltage for a 3-V supply is 2.46 V under a 12-mA load. This means that the maximum for each inverter is 45 Ω, which gives us 9 Ω for ...
    Dec 4, 2025
24. Circuit improves on bias for GaAs FETs
    Tom Roberts
    Circuits Supply Amplifiers Analog Devices LT1085
    .. has 0 V on the gate and 1.25 on the drain can result in damage to the device. For example, M/A-Com's MAAM26100-PI MMIC power amplifier requires 8 V for V DD and 5 V for V GG . With 1.25 V on V DD and 0 V on V GG , the MMIC draws ...
    .. as well as to the order in which these biases turn on and off. A GaAs-FET amplifier that uses two bias voltages a negative supply, V GG , on its gate and a positive supply, V DD , on its drain requires that V GG be present before the ...
    Dec 3, 2025
25. Circuit offers series protection against power-line transients
    Alfredo Saab
    Circuits Supply Analog Devices MAX1614
    .. transients on low-voltage power lines can sometimes attain amplitudes many times the nominal voltage level. That behavior often calls for ...
    .. This circuit protects a load, connected to the right pair of terminals, from undervoltage and highvoltage transients in the supply voltage, connected to the left pair of terminals. In the circuit, which powers loads as heavy as 1 A from a ...
    Dec 1, 2025
26. A simpler circuit for characterizing JFETs
    John L. Waugaman
    Circuits Measurement ON Semiconductor MPF102 MPF4392
    .. R1, R3, R5, D2, and TEST pushbutton S3 comprise the simple current limit circuit (R4 is a parasitic Q-killer). S3 supplies power to S1, the polarity reversal switch, and S2 selects the measurement. J1 and J2 are banana jacks for the DMM set ...
    .. Use components on hand as much as possible. Accommodate both N- and P-channel devices while using a single voltage supply. Use a wide range of supply voltages. Incorporate a current limit with LED indication when the limit is ...
    Nov 26, 2025
27. A precision, voltage-compliant current source
    Christopher Paul
    Circuits Supply Texas Instruments TLA431 TLVH431B
    .. U 1 strives to establish a constant voltage at V S regardless of the DC and AC voltage variations of the unregulated supply V 1 . Working against it in descending order of impact are the magnitude of the conductance of the R 3 + R 4 ...
    Nov 25, 2025
28. Circuit makes square deal
    Stephen Woodward
    Circuits Analogue Design Texas Instruments OPA2228 OPA4228
    .. classic nonlinear analog function is the squaring circuit. It’s useful in power sensing, frequency multiplication, RMS computation, and many other odd jobs around the lab bench. Figure 1. The ...
    Nov 25, 2025
29. CMOS Schmitt trigger IC makes VCO
    David A. Johnson
    Circuits Oscillators Beginners Lingxing Microelectronics CD4584
    .. changing the supply voltage fed to a classic 4584 Schmitt trigger type oscillator, the oscillator frequency can be changed over a ...
    Nov 24, 2025
30. Protecting your prototype with automotive overvoltage protection
    Simon Bramble
    Circuits Supply Analog Devices MAX16126
    .. prototyping. This simple circuit can prevent hours of rework caused by momentary lapses of concentration when an incorrect power supply is applied to a circuit. Introduction The good thing about being a field applications engineer is that ...
    Nov 21, 2025

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