Article
Universal Symmetric Power Supply
This power supply has been specially designed for the 20th-order filter described elsewhere in this issue, but it can also be used for a legion of other opamp circuits. The supply voltage is set to ±17.5 V, in light of the maximum output level of the filter. This benefits the signal to noise ratio. The specified absolute maximum supply voltage for most opamps is ±18 V, and we have intentionally kept a bit below this limit.
Materials
Gerber file
CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor GREEN and GOLD members can exclusively download these files for free as part of their membership. Gerber files allow a PCB to be produced on an appropriate device available locally, or through an online PCB manufacturing service.
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PCB
Component list
Resistors:
R1,R3 = 249? 1%
R2,R4 = 3k?24 1%
R5 = 8k?2
Capacitors:
C1,C2,C7,C8 = 100nF ceramic
C3...C6 = 10µF 63V radial
C9,C10 = 220µF 40V radial
C11-C14 = 22nF ceramic
C15,C16 = 100nF 275VAC class X2
Inductors:
L1 = 2x27 mH (e.g., Siemens type B82721-K2401-N21) (Electrovalue)
Semiconductors:
D1 = high-efficiency LED
IC1 = LM317T (TO220 case)
IC2 = LM337T (TO220 case)
Miscellaneous:
K1 = 2-way PCB terminal block, raster 7.5mm
B1 = B80C1500, rectangular case (80V piv, 1.5A peak)
F1 = fuse, 32mA slow, with PCB mount holder and cap
Tr1 = mains transformer, PCB mount, secondary 2x18 V/4VA (e.g., Hahn type BV UI 302 0156)
PCB, order code 004064-1
R1,R3 = 249? 1%
R2,R4 = 3k?24 1%
R5 = 8k?2
Capacitors:
C1,C2,C7,C8 = 100nF ceramic
C3...C6 = 10µF 63V radial
C9,C10 = 220µF 40V radial
C11-C14 = 22nF ceramic
C15,C16 = 100nF 275VAC class X2
Inductors:
L1 = 2x27 mH (e.g., Siemens type B82721-K2401-N21) (Electrovalue)
Semiconductors:
D1 = high-efficiency LED
IC1 = LM317T (TO220 case)
IC2 = LM337T (TO220 case)
Miscellaneous:
K1 = 2-way PCB terminal block, raster 7.5mm
B1 = B80C1500, rectangular case (80V piv, 1.5A peak)
F1 = fuse, 32mA slow, with PCB mount holder and cap
Tr1 = mains transformer, PCB mount, secondary 2x18 V/4VA (e.g., Hahn type BV UI 302 0156)
PCB, order code 004064-1
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