3-5-9 VDC Regulated Power Supply

This is an universal power supply with one regulated output, made by me in 1990. The voltage value is selectable by switch from: 3, 5 or 9 VDC. This device uses a LM723 integrated circuit. By using an additional power transistor with heat sink at output and a the current limiter circuit included in LM723, the reliability and thermal stability of the power supply is increased.

Figure 1
Figure 2
Figure 3

- linear regulated power supply
- input voltage: 230 VAC / 50 Hz
- one output with the value selectable by a switch from 3, 5 and 9 VDC
- maximum output current: 200mA
- output protection with current limiter at 240 mA
- medium power NPN transistor BD135 with heat sink on output
- line regulation: typic 0,01%, max 0.1%

Figure 4
Schematic (PDF)
Figure 5
PCB Layout

Disclaimer: The information on this web site is provided "AS IS", without warranty of any kind. The author has made the best efforts to ensure the design and the information provided are reliable. Under no circumstances shall the author be liable for any direct, indirect, incidental, special or consequential loss, damage, expense or injury incurred or suffered which is claimed to resulted from use of this site, even if expressly advised of the possibility of such loss, damage, expense or injury, including, without limitation, any fault, error, omission, interruption or delay with respect thereto.

[1] - LM723 datasheet