Tag Archives: Power supply

$14.5 All-Purpose Switched-Mode Power Supply

Switching technology devices and integrated circuits are growing fast providing solutions that obtain power for different kind of circuits and devices, and they are proposed in different variations. A useful little known kind which is suitable for mixed supply systems is called SEPIC,single-ended primary-inductor converter.

Torpedo is a switched-mode power supply with a SEPIC configuration which is produced by Open Electronics, an open source solutions producer and the brainchild of Futura Group Srl. It supports three different wide-range voltage sources, battery, USB, and external source from 3 to 20 volts with up to 1 A output current and integrated LiPo battery cell charger.

Torpedo Board
Torpedo Board

Torpedo comes with these features:

  • Triple power source, that is to say: the USB, the battery and an external one
  • Wide range of values as for the input voltage: from 3 to 20 volts
  • Minimum output current of 500mA, with the possibility to reach 1A and more, via an external source
  • High efficiency, above 70% and possibly above 80-90%
  • Single-cell LiPo battery charger incorporated
  • A transition from battery power to another source that is without interruptions
  • 5 V output with high stability, having a low ripple and when varying the load.

Torpedo’s circuit structure can be functionally divided into three different parts; Input Stage, Battery Charger, and SEPIC Converter.

At first, the Input Stage is composed of two diodes and a MOSFET transistor. This set forms a power source selector by allowing the highest voltage power source to pass through Vin pin and prevent it from going to another input having a lower voltage.

Torpedo Circuit Diagram
Torpedo Circuit Diagram

The Battery Charger is based on the MCP73831-2 integrated circuit, that is envisaged for charging single-cell LiPo batteries having a voltage of 4.2 volts. It comes with a red LED indicating the statues of charging, and a two-resistor bridge giving two different output current, 100mA and 500mA.

The SEPIC Converter in general is a DC/DC converter which control its output to be greater than, less than, or equal to that at its input. In Torpedo circuit, the SEPIC integrated circuit contains 1.2Mhz oscillator with variable duty cycle, a low-RDSON MOSFET, and a feedback circuit. This combination provides constant 5V output voltage from variant input voltage between 2.5V to 20V.

Torpedo is available for $14.5 from Open Electronics store, and its technical details are reachable here.

EspoTek Labrador – Oscilloscope, Signal generator, Power supply in one tiny board

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EspoTek Labrador is a small, portable, USB-connected electronics lab-on-a-board that includes an oscilloscope, waveform generator, power supply, logic analyzer, and multimeter.

The EspoTek Labrador plugs directly into a solderless breadboard and connects to any Windows, Mac, or Linux computer via microUSB. A custom software interface lets you see and interact with your waveforms on-screen. Careful planning and a lot of work has been put into making the interface intuitive for those new to electronics, while keeping it powerful for those familiar with the instruments. Experienced engineers, don’t fear – you can do things like manually adjust the ADC gain and UART parameters. These kinds of function have just been moved away from the main screen, keeping things clean and simple for newer users.

EspoTek Labrador – Oscilloscope, Signal generator, Power supply in one tiny board – [Link]

ElbSupply – Linear Bench Power Supply With Constant Current and Voltage Modes

A lot of power supply designs are here and there on the Internet, but not all of them have constant current and voltage modes. You can read the following Q&A in electronics.stackexchange to learn what constant current and voltage modes mean.

Elia over Hackaday.io built a linear bench power supply with the following features:

  • Output voltage range: 0 – 15V.
  • Output current range: 0 – 3A.
  • Constant voltage with current limiting and constant current modes.
  • LCD interface.

EliaSupply

ElbSupply Inside

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LT3083 the adjustable 3A low dropout regulator from Linear technology is used to provide the output voltage.
To reduce the power dissipation in the linear regulator, supply voltage is not connected directly with the adjustable LDO regulator input. Elia added a stage to reduce the input voltage of LT3083 to (Vout+2) using a buck converter. This Buck converter, TI TPS54331, is configured to follow the output voltage of the adjustable regulator plus 2 volts as an output voltage of the buck converter.

ATmega8 MCU is used to drive the 16*2 LCD, read values from the rotary switch STEC12E08, read user buttons and to produce the reference PWM signals for voltage and current.

These PWM signals are converted to analog value, the way used to convert the PWM signal to an analog value proportional with PWM is by using “resistor, a capacitor and an opamp”.
LM334, an adjustable current source, used in the output voltage of LT3083. Elia said in a log, it is needed for stable operation, the LT3083 needs a minimum load current of 1mA.

Design Files and Source Code

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ElbSupply is an Open-source hardware project. You can download the source files from the GitHub repository.

PCB and schematic are designed using KiCAD and source code was written in C with state machine code methodology.
[Project Page]

Dual output step-down charge pump operates without inductors

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Linear Technology’s LTC3256 is a high voltage low noise dual output power supply, which takes a single positive input and generates 5V and 3.3V step-down supplies with high efficiency and no inductors. by Julien Happich @ edn-europe.com

The device features a wide 5.5V to 38V input voltage range and includes independently enabled dual outputs: a 5V 100mA supply, and a 250mA 3.3V low-dropout (LDO) regulator, for a total of 350mA available output current.

Dual output step-down charge pump operates without inductors – [Link]

A Bench Power Supply using computer PSU

As we know, PSU in computers provides various DC voltages, 3.3V, 5V and 12V. These 3 levels are the most common ones needed in our labs, so usually PC PSUs are used by a lot of makers and hackers as their personal bench power supply. The PSU has a standard connector called ATX, you can reach all of the voltages levels using it.

[Supercap2F] hacked his own PSU into a bench power supply and published the project details. Supercap2F’s power supply design include:

  • PIC18F1220.
  • 16*02 LCD as a user interface.
  • Three switches for user control (select/move).
  • Relays controlled by PIC18F1220 to switch outputs on/off.
  • Fused Outputs: +3.3V, +5V, +12V and -12V.

SchematicPSU

[Supercap2F] published the circuit designs (PCB&SCH) and source code for PIC18F1220 over Github.

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Via: Hackaday

Dual Adjustable Regulated power supply 1.2V TO 37V DC

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This project is a solution to power up most of devices or projects requiring dual (+/-) adjustable power supply. The circuit is based on LM317 positive and LM337 negative voltage regulators. LM3X7 series of adjustable 3 terminal regulators is capable of supplying in excess of 1.5A over a 1.2V to 37V DC output range. On board TO220 Package with heat sink can handle maximum load current. Board provided with two on board preset to adjust the voltage.

Dual Adjustable Regulated power supply 1.2V TO 37V DC – [Link]

Adjustable HV Power Supply for Stompbox

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This SMPS can be powered with low input voltage, from 5 VDC to 15 VDC and provided adjustable Output Voltage: + 92 Vdc to +340 Vdc.

Can be used too, as power supply, for the Xenon Lamp, Nixie tube Clock, VFD display, Magic Eye, Neon, and too many others electronics circuits who need HV power supply to work. Is great to use with many models of Nixie tube. It can drive 6 Nixie tubes, in multiplex mode, from 180 to 200V. Powered with low voltage from 5VDC to 15 VDC. With this SMPS you can power 250V @ current of 7.5mA! *In all case above, important note, DC and AC filters must be improved, if is desired reducing present HF frequency noises at output! Another fact, informed before, the RF energy is irradiated as magnetic and electric field, shielded assembly could be necessary!

Adjustable HV Power Supply for Stompbox – [Link]

5V Step Down DC-DC Converter

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The Tiny Step-Down DC-DC converter project provides 5V 500mA output from supply input up to 25V DC. MC34063A IC is heart of the project from on semiconductor. The MC33063A is a monolithic control circuit containing the primary functions required for DC-DC converters, This device consist of an internal temperature compensated reference, comparator, controlled duty cycle oscillator with an active current limit circuit, driver and high current output switch. This IC specially designed to be incorporated step-down, step-up, and voltage-inverting applications with minimum number of external components.

Features

  • Input 12- 25V
  • Output 5V, 500mA
  • Output filter for clean output
  • Output Voltage Fine Adjustable 20%
  • Header Connector for Output/Input Connections
  • Low Standby Current
5V Step Down DC-DC Converter – [Link]

Teardown: 12V AC adapters

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Michael Dunn has done three teardowns of the worst 12V adapters and what he found is interesting.

Yes! Can you believe it? This board used to be in another adapter housing, or more likely, in an end-product. It seems Chinese manufacturing has sunk to a new low: repackaging used and/or surplus power supplies. On the plus side…recycling.

Teardown: 12V AC adapters – [Link]

Linear Bench Power Supply

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Matt Godfrey published his linear lab power supply which has adjustable voltage and current limit. Specs: 0-30V, 0-2A, separate 5V output, display of setpoint and output current and voltage:

This project is a simple linear bench power supply with adjustable voltage and current. It is meant to be a learning experience, putting ideas of circuit design, feedback, stability into practice building a complete practical power supply. I have intentionally avoided using a 3 terminal regulator or purpose built chip and instead implemented the feedback for voltage and current using a couple of opamps. The idea is for this to be a practical final product while giving practice implementing some basic circuits.

Linear Bench Power Supply – [Link]