9 VDC Regulated Power Supply

Rajkumar Sharma      http://www.rajkumarsharma.com  
Project tested


Tiny low current 9 VDC Regulated Power supply designed around bipolar transistor and zener diode. The circuit is known as series voltage regulator or emitter follower voltage regulator. The unregulated supply fed to input and the circuit regulate the voltage and provide constant 9V DC, 250mA. The zener diode provides the reference voltage to the base of the transistor. This is very suitable power supply for small projects as it can provide any supply output by changing just the zener diode. A transistor heat sink may be required if the output current is high.

Other output voltage can be obtained by changing the zener diode

Output Voltage Formula Vout=Vz-VBe

Vz=Zenner diode Voltage, VBe=0.7V


  • Input – 12 VAC or DC, 500 mA
  • Output – 9.3 VDC / 250 mA, Zener regulated low ripple DC voltage
  • Input bridge rectifier made from discrete Diodes
  • LED indication for output
  • Terminal pins for connecting input and output
  • Four mounting holes of 3.2 mm each
  • PCB dimensions 29 mm x 44 mm



Parts List




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