Circuits & Schematics: power supply - 2

11. Single sideband radio meets LMC555 beat frequency oscillator
    Stephen Woodward
    Circuits Oscillators Radio Texas Instruments LMC555
    .. the carrier and redundant sideband is good because it increases transmission efficiency in both bandwidth and transmitter power utilization. But it adds complexity to the receiver because then it must provide the missing reference ...
    .. oscillator is tuned by R1. The amplitude of the injected IF signal is adjusted by R3. It works happily with a wide range of supply voltages and so needs no regulator. Here’s how it works. Both single-sideband suppressed carrier (SSB ...
    Aug 25, 2026

12. Add-on beat frequency oscillator (BFO) for shortwave radio
    Gavin Watkins
    Circuits Oscillators Radio Antique Texas Instruments LP2950
    .. (Reg 1 ) is included. A 78L05 could be used, but in this application the radio used a Realistic Patrolman SW60 had a 6 V supply, so a low-drop out LP2950 regulator was used instead. A photograph of the BFO built in a small plastic box ...
    Aug 25, 2026
13. Automotive low side output switch architecture suitable for 8 to 48 volt buses and beyond
    Vishwas Vaidya
    Circuits Automotive Supply Nexperia MMBTA42 MMBTA92
    .. solutions available from global automotive semiconductor companies suffer from the following weaknesses: No off-the-shelf power switch IC is currently available beyond 24 volts, whereas upcoming vehicle architectures are envisioning 48 VDC ...
    Aug 17, 2026
14. Phantom-powered solid-state linear airflow sensor
    Stephen Woodward
    Circuits Measurement Texas Instruments TLV2197 LM7905
    .. Darlingtion transistor pair linearly senses airflow using just two wires for both power in and signal out. Suppose we take a common TO-92 transistor and heat it to a constant temperature differential ...
    .. handy for air flow measurement. Maybe even moreso if it needed only a simple two-wire connection for both (phantom) power supply from, and signal delivery to, the supporting electronics. Please see the Related content listings below for a ...
    Aug 11, 2026
15. Push to increase, decrease a digital potentiometer
    Jayapal Ramalingam
    Circuits Digital Analog Devices AD5220
    .. by one step. Similarly, each “DEC” (decrement) push button press decreases resistance by one step. The power supply and ground pins of the various ICs are not shown in this schematic. This simple design uses only two ICs ...
    Aug 11, 2026
16. An off-line power supply
    Gavin Watkins
    Circuits Supply Texas Instruments LM317
    .. as it is only 50% efficient, and any dropped battery voltage will be dissipating as heat. However, assuming renewable power generation is used as the source, this would prove a more environmentally friendly solution compared to using ...
    .. around an LM317 linear voltage regulator in a nice black plastic enclosure sold by Maplin Electronics as a “power supply” box. The NiCd battery hadn’t been used for over 20 years, so this project would be a repurpose. ...
    Jul 29, 2026
17. Method provides fast, glitch-free isolation of I²C and SMBus signals
    Mark Thoren
    Circuits Interfaces Microcontrollers Usage Broadcom HCPL-2300
    .. 2 C is a popular serial protocol for power controllers, ADCs and DACs, EEPROMs, and other devices. In certain data-acquisition and power-control ...
    .. fight each other and form an oscillator (Figure 3). The characteristics of this oscillation depend on pullup resistance, supply voltage, and capacitance data lines. (Removing one of the 9-pF scope probes stops the oscillation, and ...
    Jul 28, 2026
18. Bidirectional solid state relay
    David A. Johnson
    Circuits Beginners Nexperia PMV30UN
    .. turn on hard from the 1.5 V from the red LED. The bi-directional configuration allows the circuit to switch both AC and DC power. Using quality super bright red LEDs, the circuit will switch on fully with only 5 mA of LED current. Materials ...
    Jul 27, 2026
19. Medium power 12V brush motor speed controller
    David A. Johnson
    Circuits Supply Intersil CA3240 CA3260
    .. many applications, you would like to hold the speed of a motor constant, even as variations in the power supply voltage or mechanical load try to change its speed. In other applications, the average current to the ...
    Jul 27, 2026
20. Build a practical 400 mA linear Li-ion charger with visible CC-CV behavior
    Richard O. Ocaya
    Circuits Supply Texas Instruments LM324 LM431
    .. The circuit offers a practical alternative for engineers who require simplicity, transparency, and predictability in low-power Li-ion charging applications. Materials on the topic Datasheet Texas Instruments LM324 Datasheet Analog Devices ...
    .. particularly for designers who value analytical transparency and first-principles reasoning. It operates from a 5 V supply, commonly found in 5 V/1 A smartphone chargers, delivers 400 mA of constant current (CC), then transitions to ...
    Jul 27, 2026

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