• on Audio/Video/Photography
  • Published in issue 7/2005 on page 0
About the article

Universal I/O for Power Amps


Universal I/O for Power Amps
This two-part circuit was designed as an addition to the 'Compact 200 W Output Stage' in this issue. But it is also suitable for use with IC amplifiers that don't have their own power-on delay.
The circuit consists of an input stage (nothing more than a resistor and capacitor) and a power-on delay with a relay for the amplifier output.
A small PCB has been designed for the input signal. This board contains a phono socket, capacitor and a resistor that is connected directly across the input.
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Gerber file

CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor 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. Elektor recommends its business partner Eurocircuits as the company of choice for its own prototypes and volume production in selected cases.

R1 = 270k
R2 = 1k2
R3,R4 = 1M
P1 = 250k preset
C1 = 4µF7 MKT or MKP (see text)
C2 = 47nF
C3 = 10µF 63V radial
D1,D3 = 1N4148
D2 = zener diode 24V 1.3W
D4 = 1N4002
T1 = BS170
K1 = cinch socket, PCB mount, e.g. Monacor / Monarch T-709G
K2, K3 = spade terminal, PCB mount, vertical, 2 pins
RE1 = PCB relay 24 V/16 A (e.g., Omron G2R-1-24, 1100 Ohm, or Schrack RT314024, 1440 Ohm)
PCB, ref. 054010-1
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