Simpe Soft-Start + DC Blocker + Mains filter

Simple soft-start for the transformer works in very simple way. Two relay coils are driven by the CX3 capacitor reactance, sufficient time delay is provided by C6 capacitor. It is very important to use 24V DC coil relays with resistance 1,44kR.

Two LED's are informing when each relay is active.  The amplifier can be switched ON/OFF with only 20mA so there is no need to use huge ''hefty'' power switch anymore.

During the start-up the mains current is limited with two 47R/5W resistors connected in parallel, the max current for 230VAC mains is approx 10A. After a few seconds Relay2 ''kicks in'' and the current limiting resistors are clamped.

On the board there is build in mains filter and DC-Blocker, both of the components should be placed in any amplifier anyway so I decided to ''melt'' them on a single board.

 

Schematic and gerber files are on the bottom of the page.

!!! PLEASE BE CAUTIOUS WHEN WORKING ON MAINS VOLTAGE !!!

 

Best Regards