Every lab needs to be equipped with essential equipment. Out of all I would say power supply is most important since it powers up the projects. 

Batteries, DC adapters can do fine job but as demand grows and project gets bigger a professional and adjustable power supply becomes a necessity. To cater that I have designed an adjustable 30V / 10A Diy Bench power supply Circuit with a variable output from 0V to 30V and adjustable current limiting from 0A to 10A. 

This is the Best Variable power supply Circuit Diagram. You can increase its output ampere just add more TIP3055 Transistor in parallel 

Parts List for Diy Bench Power Supply

  • 1x LM 317 Regulator Integrated
  • 2 x .1uf Capacitor
  • 1 x 5K Potentiometer
  • 1 x 10K Potentiometer
  • 1 x 220R Resistor
  • 1 x 1K Resistor
  • 1 x 5mm LED
  • 2 x 0.10R to 1R 5W Resistor
  • 1 x 1000uF 35V Capacitor
  • 1 x BD139 Transistor
  • 2 x TIP3055 Power Transistor
  • 2 x Aluminum Heatsink

Variable Power Supply Circuit Diagram

diy bench power supply

Simple Circuit Diagram

diy bench power supply circuit diagram

Temperature Controlled Fan Circuit

This simple temperature controlled DC fan circuit can be used to control any 5volt DC fan by activating it on a preset temperature. You can use this circuit in many electronic projects, which require a cooling fan. The circuit is very simple.
 
The BD139 transistor is working as a switch here. When the 10K NTC thermistor will receive heat then its resistance will start decreasing and on a preset level the transistor BD139 will become switch ON and activates the 12 volt DC fan or motor. The 50K variable resistor is used to set the level of temperature or heat on which you want to switch ON the transistor.
 
The transistor will dissipate heat during operation therefore it is important to add some distance between the thermistor and transistor or the circuit will not work properly. Also use a suitable heatsink with the transistor.
Bench Power Supply/Battery Charger

Click Here For  Very Sensitive Temperature Controlled Fan Circuit

PCB Layout for Power Supply Circuit

Bench Power Supply/Battery Charger

Final Circuit Diagram With Volt and Ampere Meter

Bench Power Supply/Battery Charger

Watch Video:- How to Make Variable Power Supply Circuit

Watch Video for Bench Power Supply circuit

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