[Successful test] Student adjustable power supply

Don’t ask, as long as it works!

The open source license of this project is CC-BY-NC-SA 3.0 (Creative Commons License-Attribution-NonCommercial-ShareAlike). You must give appropriate attribution, provide a link to this license agreement, and indicate whether (for original work) has been modified; if you remix, transform, or create based on this work, you must share and publish your contributed work under the same license agreement as the original license agreement; you may not use this work for commercial purposes.

Shell Taobao link

Device parameters

1. Input voltage DC 12-24V
2. Current MAX 2A
3. Minimum output voltage DC 1.2V
4. Maximum output voltage DC input voltage -1.5V

Setting protection current method

1. Power on, turn the onboard potentiometer counterclockwise to the maximum value, press the button, and the relay will close.
2. Slowly turn the potentiometer clockwise until the relay just opens
3. Rotate the potentiometer counterclockwise a little, press the button, the relay will close, and you can start using it.
4. When the circuit is overloaded or short-circuited, the relay will automatically disconnect
5. After removing the fault, press the button to continue using

Instructions

1. Connect to the DC power supply, set the protection current, and adjust the "voltage regulating potentiometer" to adjust the output voltage.

Precautions

1. LDO needs to add a heat sink to prevent overheating (it is the hottest on the entire board, hotter than LM2596)
2. LM2596 needs to add a heat sink, and it is recommended to use a cooling fan
3. Cement resistors can be selected with different powers according to their own needs.

User experience

1. I am using a 24V 1.5A switching power supply purchased from a certain store for 8 yuan with free shipping. The measured power is sufficient.
2. The current measured output can reach 1.8A MAX
3. With the support of the cooling fan, the temperature of the LM2596 can be kept below 45°C (maximum output), but the HK7550 is not so good, and the temperature is often kept at 80°C.
4. The voltage and ammeter shown on the cover feels better and has a small current error. However, there is still an error of ±0.3V after voltage calibration. Those who do not have high requirements can use it with confidence.
5. It is recommended to use a multi-turn potentiometer for more accurate voltage regulation. I used a 1-turn potentiometer, but the voltage regulation accuracy is much lower.

Chaos.jpeg