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Digital Controlled Bench Power Supply

There have been quite a few nice power supply projects based around the XL4015 buck converter module. It is a great module for this type of project as it has a wide range of voltage output and decent current capability. It is also available with modules that give multi-turn potentiometer setting of the voltage and extra circuitry to allow for an adjustable current limit.
The difference with this instructable is that I have made it digitally controlled on both the voltage and current limit settings and provide for measurement and display of the voltage and actual current being drawn. The controller used is an ESP8266 module which means it also gets a web interface and opens up more possibilities for control.

This gives it the following features:

- Output voltage digitally settable between 1.25 and 19.0V
- Current output up to 5A (4A more realistic to avoid thermal shutdown).
- Local control of voltage and current limit via rotary encoders allowing high precision
- Local display of voltage, current draw and current limit on an OLED display
- Secondary fixed output voltage of 3.3V or 5V (1.5A)
- Browser interface to view measure values and set voltage and current limits
- Ability to capture logged voltage and current data to files.
- Ability to playback voltage profiles from files and capture current data
- Browser also allows file system management, configuration and software update.

- XL4015 buck converter with adjustable voltage and current limit
- ESP8266 (ESP12-F) wifi microcontroller module
- ads1115 4 channel 16 bit I2C ADC
- SD1306 0.96” OLED I2C display module
- 2 MCP4725 12 bit I2C DAC
- Mini buck converter with adjustable output (MP2307)
- 2 Rotary encoders EC11
- 12V 40mm fan (can be 20mm or 10mm high)
- mini slide switch
- n-channel MOSFET AO3400
- Electrolytic capacitor 220uF
- Resistors 47R,390R,470R,1K,10K,2K2,11K2,100K
- 2.5 /5.5mm power input jack (vary to suit lap top brick connector
- 4 position spring speaker terminal connector
- 2.5mm bolts and nuts for board mount, 3mm bolts and nuts for fan mount.
- Enclosure. My 3d printed design is at 2 versions depending on fan height.
- Old lap top power brick e.g.19.5V 4A”

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