Active DC constant current electronic load

Introduction

Active DC constant current electronic load uses Intel 775 radiator, designed power is 90W (actual stable 120W), and comes with a voltage and ammeter.

safety warning!

When the electronic load is working, there are many risks such as electric shock, high temperature burns, and physical damage caused by the high-speed rotation of the fan, which may lead to personal injury, disability, or death. Please operate in strict accordance with safety regulations and provide adequate protection. Minors should operate with the assistance of a guardian. Producing and using this product by yourself means that you have a sufficient understanding of the security risks, and you are responsible for any losses and consequences caused. Neither the platform nor the author assumes any legal responsibility.

characteristic

• Using Intel 775 cooler
• Active design, power supply voltage: 12V.
• Load terminal input voltage: 1~30V, maximum constant current value: 10A.
• The maximum designed power is 120W.
• Variable maximum constant current value and maximum power are determined by the heat dissipation conditions during production.
• Low internal resistance
• Soft switching function.
• Comes with voltage and current meter head, controlled by STM32F030K6T6.
• Power tube temperature monitoring
• Temperature controlled fan, four-wire PWM fan control (compatible with 3-wire and 2-wire fans)
• Perfect protection function.
  • Overheating protection
  • Fast-acting fuse at load input
  • Over current protection
  • Over power protection
  • Reverse connection protection
  • ADC port protection
• All raw materials are cheap and easy to obtain, making it easy for personal production.
• Voltage and ammeter supports software calibration
• Open source code

Precautions

• R18 is used to control the maximum constant current, which is about 3A when measured at 100kΩ. If you want to reach 10A, it is recommended to use 22KΩ. Higher currents require better terminal blocks and more powerful cooling systems.
• It is recommended to use relatively good quality input terminals at the load end.
• There is a window area reserved on the PCB for tin stacking. The current design can be stable over 10A without tin stacking. It is recommended to choose whether to stack tin based on the actual situation during production.
• It is recommended to deposit tin in the following areas: solder joints of terminals; connections between diodes and MOS.
• JP1 jumper is reserved for debugging, do not short circuit
• JP2~JP4 jumpers are fan control selection jumpers. You need to follow the table instructions in the schematic diagram to select whether to short-circuit according to the fan type.
• If you cannot buy a dedicated 4-wire fully compatible KF2510 fan seat, you can use a 2.54 pin header instead.
• The NTC value used in the schematic diagram is 100k, but because there is no suitable NTC on hand, an NTC with a B value of 10K and a B value of 3950 is used. If you use a different NTC, you need to recalculate the temperature comparison table. It is recommended to use 100K NTC when making it yourself.
• Some fans may not be able to stop due to their anti-stall protection.
• The source code is a trueStudio project. For details on how to use it, see "Using TrueStudio to import, compile, and download STM32 programs.pdf" in the attachment.

Physical picture

Front view

side view

Voltage ammeter

speed of the fan