Tag Archives: Power supply

LiFeP04wered/Pi+, A High-Performance Battery Power System For Raspberry Pi

LiFePo4wered/Pi+ is simply a better version of the LiFePo4wered/Pi3 and the LiFePowered/Pi. These devices are all designed to solve the issue of power supply to the raspberry pi. LiFePo4wered is simply a high-performance battery power system which is acting as an option for raspberry pi projects where the likes cellphone adapters and USB power banks cannot fit in.

Power is one of the significant factors in the use of the Raspberry, most Raspberry Pi projects are usually plugged into a wall power adapter which at some could impact on the mobility and portability of the project, but with the LiFePo4wered/Pi+ you don’t have to worry about plugging your project into a wall socket. It can power a Raspberry Pi for up to nine hours from its battery (depending on installed battery size, Raspberry Pi model, attached peripherals, and system load) and can be left plugged in continuously.

LiFePo4wered/Pi+ might probably end up as the best source of power supply to the raspberry pi, and the primary advantage is that it works with all models of the Raspberry Pi. The LiFePo4wered/Pi+ can provide a steady continuous current supply of 2A to the Raspberry Project; this is usually like the max most Raspberry Pi project will use an unlikelihood one will be capped at that max but the general standard of about 700mA.

The following are some of the features of the LiFePo4wered/Pi+:

  • 1500 mAh 3.2 V LiFePO4 battery: Uses a Lithium iron phosphate that provides safety, high power density and extended cycle life of 2000+ cycles. The battery can also be used as a UPS.
  • Optional 600 mAh, 3.2 V LiFePO4 cell: This is merely a smaller battery for low power applications or when there is power loss in the main battery.
  • 2 A continuous load current: Can supply this with 1500mAH battery option or using an external source of power.
  • A Smart charge controller:
    • Over-charge protection: This feature allows the device to stay plugged in continuously without exploding because it stores the extra charge to help it serve as a UPS when needed.
    • Auto-adjusting charge current: Regular charge current can be up to 1.5 A when used with high power chargers. However, it will automatically reduce current when needed not to overwork low power sources when they are used.
    • Customizable MPP (Maximum Power Point) voltage: This helps to obtain maximum efficiency when powered directly from suitably sized solar panels.
  • Others:
    • On/off button: provides convenient boot/shutdown triggers even in headless setups, with the press and hold function to prevent accidental activation (external button can be added).
    • Green PWR LED: This indicates the Raspberry Pi power state, and it provides feedback to the user. External LED can be included.
    • Red CHRG LED: This tells the user when there is a power loss and when there is a need to charge the batteries.
    • Wake timer: This allows the Raspberry Pi to be off until when it’s needed for low duty cycle applications.
    • Real-time clock: It keeps track of time and makes sure the raspberry pi comes on at a programmed time.
    • Autoboot: Makes the Raspberry Pi run whenever there is sufficient battery power, or when an external power supply is available.
    • Auto shutdown: Automatically shuts the Raspberry Pi down when there is a power loss or after a programmed amount of time.
    • Application watchdog: can alert a user by flashing the PWR LED or trigger a shutdown/reboot if the user application fails to service the timer within a configurable amount of time.
  • Compatibility: Works with every known model of Raspberry Pi, this includes Raspberry Pi Model A+, Model B+, Raspberry Pi 2, Raspberry Pi 3, Raspberry Pi 3 Model B+, Raspberry Pi Zero and Raspberry Pi Zero W.
  • Hackers Friendly: It has convenient connection points for input power, 5 V output power, switched battery power, external button and LEDs(Light Emitting Diodes), and MPP customization.
  • Software:
    • LiFePO4wered daemon: This is responsible for the auto shutdown and real-time clock (RTC) duties.
    • Command line tool: allows simple configuration and access to all features.
    • Shared library, language bindings: C/C++, Python, and Node.js bindings allow integration into user programs.

The LiFePo4wered/Pi+ is planned for a crowdfunding campaign on crowd supply, and more details of the project campaign are available on the campaign page.

Designing a Small Footprint, Low Profile 5v to 170v Nixie Tube Power Supply

Nixie Tubes are cool retro looking decimal digit displays useful for many modern DIY projects like the venerable Nixie Tube digital clock.   The Nixie Tube, invented in the 1950’s, can provide a great fusion of old display technology with new innovations.  Unfortunately, one major difficulty in using them is that Nixie tubes need voltages up to 170V to energize.  While this voltage can be made several ways, a convenient way and the subject of this blog is to generate this voltage from a 5v supply.  This will allow the use of the same 5v supply used to power the Raspberry Pie, an ESP8266, an Arduino or another microcontroller that controls the display or IOT project.

Designing a Small Footprint, Low Profile 5v to 170v Nixie Tube Power Supply – [Link]

1.2V-25V/10A Adjustable Power Supply Using Power Op-Amp

This is a small size power supply based on OPA549 power op-amp that provides output voltage 1.2V to 25V with 0 to 10A adjustable current limit. Two onboard trimmer potentiometers provided to adjust the voltage and current, LED D1 is over temperature indicator. The circuit works with input supply of 30V DC and logic supply 5V DC. IC requires large size heat sink to work with full 10A current range. Screw terminals for input and output connections are provided. The OPA549 is a low-cost, high-voltage/high-current operational amplifier ideal for driving a wide variety of loads. This laser-trimmed monolithic integrated circuit provides excellent low-level signal accuracy and high output voltage and current. The OPA549 operates from either single or dual supplies for design flexibility. The input common-mode range extends below the negative supply.

1.2V-25V/10A Adjustable Power Supply Using Power Op-Amp – [Link]

Flexipower – A portable, Controllable, Dual Channel Power Supply

Hobbyists, makers, students and pretty much everyone who works with electronics has encountered the same issue, not having a handy power supply to test their projects. Usually, controllable power supplies are big, expensive and for some people difficult to access, and most small power supplies are not controllable. As a result, Roberto Lo Giacco created Flexipower, a small, portable, flexible, and remotely controllable dual channel power supply.

Flexipower is controlled via a mobile application and its battery operated. It can work up to a voltage of 20 V and a current of 1 A (per channel). Power supply is powered by two cell Li-Ion or Li-Poly batteries which provide 8.4 v when fully charged, to reach higher voltages the battery is fed into a voltage step up circuit, and to get lower voltages the battery is fed into a high current linear voltage regulator. Also, a simple voltage divider along with the 10-bit ADC is used to measure the produced voltage, and adjust accordingly.

Current measuring is done through a 1 Ohm shunt resistor network made by ten 10 Ohm resistors in parallel which results in 1 mV voltage drop per mA. In the case of currents lower than 320mA, the integrated circuit INA219 is used to obtain a very precise reading. When the supplied current goes above the capacity of the INA219 the shunt resistor voltage drop is measured using the 10 bit ADC.

As mentioned before, Flexipower uses 2 rechargeable batteries that are charged via a barrel jack connecting a 12 V source capable of around 1 A. An RGB LED is used to inform the user about the status of the device (power on, battery warning, connection status etc.). The LED is also used to indicate the battery status. Additionally, each channel has a green/red LED to indicate if it is enabled (green), or over current (yellow).

Furthermore, the device can create “Flexipower SSID”, an access point for people to connect and control the power supply. The app was created to avoid using a big LCD screen with limited data logging capabilities. The app allows control, unlimited data logging and visualization just with the use of a smartphone.

For complete specifications, list of materials used, schematics and app download go to official website. The creator always tried to minimize components costs while still providing a lot of capabilities. It still can be improved, but it’s a project that could make the life of people easier. Its important to clarify that this device is not a replacement for benchtop power supplies, but for portability is a great option.

Programmable Power Supply Using OPA548

Project provides 1.2 to 20V DC output with current limiter adjustable to 0-5A. I have tested the circuit with 250mA output without a heat sink. Project is capable to drive 3A continues load and 5A peak, large size heat sink required for full load. The tiny power supply based on low cost OPA548 high-voltage and high-current operational amplifier is ideal for driving a wide variety of loads. The project provides excellent low-level signal accuracy and high-output voltage and current. The circuits operate with single supply 24V DC and logic supply 5V DC. The IC is internally protected against over-temperature condition and current overload. Trimmer potentiometer PR1 sets the output voltages, PR2 helps to set the current limit 0 to 5Amps.

Programmable Power Supply Using OPA548 – [Link]

Proto Board Power Supply

David Johnson-Davies @ technoblogy.com build a breadboard friendly power supply to power your Arduino or other low power electronics. The power supply is able to deliver 0V to 5.5V at up to 0.5A and it’s powered from two Li-Ion rechargeable batteries. The output can be adjusted using a rotary encoder, and the voltage is displayed on a three-digit 7-segment display. The whole circuit is controlled by an ATmega328.

15V 1A Dual Output Flyback DC-DC Converter

+/-15V 1A Dual output DC-DC converter is a tiny board built using Transformer from Renco and LM2587-ADJ IC from Texas instrument.  Input supply 18-36V DC.  The LM2587 regulators is monolithic integrated circuit specifically designed for fly back, step-up (boost), and forward converter applications. The power switch is a 5.0A NPN device that can stand-off 65V. Protecting the power switch are current and thermal limiting circuits, and an under voltage lockout circuit. This IC contains a 100 kHz fixed frequency internal oscillator that permits the use of small magnetics. Other features include soft start mode to reduce in-rush current during start up, current mode control for improved rejection of input voltage and output load transients and cycle-by-cycle current limiting. An output voltage tolerance of ±4%, within specified input voltages and output load conditions, is ensured for the power supply system.

Features

  • Supply Input 18-36V DC
  • Output +/-15V DC, 1Amp
  • On board trimmer potentiometer for Fine voltage adjust
  • Operation Frequency 100 KHz

15V 1A Dual Output Flyback DC-DC Converter – [Link]

Versatile And Open Source LiPo bBattery Breadboard Power Supply

Orlando Hoilett from Calvary Engineering LLC designed a  versatile Li-Po battery breadboard power supply and wrote an Instructables on it. This power supply outputs 3.3V to the breadboard and takes input from a single-cell LiPo battery. The breadboard power supply also has the ability to charge the battery without needing to separate it from the circuit board. More importantly, this project is licensed under Open Source Hardware which means anyone can modify, distribute, make, and sell this design.

LiPo bread board power supply
LiPo breadboard power supply

Key Components

The complete BOM is available at the GitHub repository.

  • JST connector
    This connector connects directly to the LiPo battery.
  • 3.3V regulator, AP2210K
    3.3V logic is getting increasingly popular among electronics hobbyists and engineers. Also, boosting 3.7V of a LiPo battery to 5V can induce quite a bit of switching noise on the power supply. Linearly converting 3.7V to 3.3V is the best way to avoid this problem.
  • Battery Charger, MCP73831T
    This power supply has a charger built into the board so you can charge the battery without removing it from the power supply.
  • Voltage Selection Jumper
    The voltage selection headers are 3 pin male headers and they are labeled as 3.3V (or VReg) and VRAW (or LiPo). Connect the center pin to 3.3V to get power from the regulator. Connect the center pin to VRAW to get power directly from the LiPo battery.
  • DPDT Switch
    This switch lets you power down the board without removing the battery.
  • LED indicators
    LEDs are used to indicate the current status of the board.

Details

This board breaks out the LiPo battery to the breadboard power rails on both sides. It has a DPDT switch to power down the board. The AP2210K IC has an ENABLE pin which is pulled down to the ground using the DPDT switch in order to enter the low power mode. In low power mode, the regulator and all the LEDs get disabled and draws almost no current from the LiPo. More about the AP2210K regulator IC is on this datasheet.

LiPo breadboard power supply schematic
LiPo breadboard power supply schematic

Another great feature of this breadboard power supply as mentioned earlier is, it incorporates an MCP73831T LiPo battery charger IC. It is a widely used PMIC (power management integrated circuit) for charging LiPo batteries. The LiPo battery should be connected to pin 3 (VBAT) and 5V should be applied to pin 4 (VDD).

The chip starts charging as soon as it detects 5V input and stops charging when the battery is full. Charging current is limited to USB standard i.e. 100mA by connecting a 10.2K resistor between pin 5 (PROG) and ground. So, it’s completely safe to charge the battery from your laptops USB port. Other host microcontrollers can check the battery status using pin 1 (status pin) of MCP73831T.

Keysight Technologies’ E36300 series bench power supplies

Martin Rowe @ edn.com presents the new Keysight E36300 bench power supply with triple output and some great features.

Keysight Technologies’ E36300 series of bench power supplies provide three outputs with power of 80 W or 160 W with line/load regulation of 0.01%. Front-panel buttons let you turn any output on or off and you can configure each output with 2-wire local sensing or 4-wire remote sensing. The 4-wire sensing removes losses caused by IR drops in your power-delivery wires.

Keysight Technologies’ E36300 series bench power supplies – [Link]

Linear Lab Power Supply with digital meter

@ instructables.com build a nice power supply for his lab. He writes:

From my point of view one of the best ways to get started in electronics is to build your own laboratory power supply. In this instructable I have tried to collect all the necessary steps so that anyone can construct his own.

All the parts of the assembly are directly orderable in digikey, ebay, amazon or aliexpress except the meter circuit. I made a custom meter circuit shield for Arduino able to measure up to 36V – 4A, with a resolution of 10mV – 1mA that can be used for other projects also.

Linear Lab Power Supply with digital meter – [Link]