Siegfried Meier

GSSL Relay using EAO Switch Thread
« on: August 16, 2007, 01:21:46 PM »
I thought I'd start a thread on exactly how to wire this up, what PCB's to use, how to wire the P/S etc., as I could not find clear info on what do use and what to do.  I'm using Greg's sidechain board, and I want to use 2 EAO switches on the front panel.  The first will bypass the unit, the second will engage the external sidechain (position 6 I believe on Greg's board).  Perhaps someone has ready made PCB's, or we can get some made.  So, what do we need and how is it done?



GSSL Relay using EAO Switch Thread
« Reply #1 on: August 16, 2007, 02:39:07 PM »
I did similar on my gssl for bypass. Tapped off  DC after the bridge rectifier, eao switched to two 24v relays switching the outputs. This is from memory but i think i drew it out. I'll have a look for it at work tommorow.

Theres alot of stuff in the forum about 'true bypass' relay circuits (switching the inputs and the outputs) but  its not necesary in most studio situations.
U don't need a pcb for the bypass. Its only a few components, stripboard is fine.
However maybe a generic relay bypass pcb would be nice if someone can be arsed to do it. Perhaps its already been done?



« Reply #2 on: August 16, 2007, 07:08:19 PM »
The original SSL design uses FET's to do the switching, so they only use a single EAO switch.
Jakob's design switches the signal in a different place and needs a seperate pole to take out the makeup gain pot.
What I did was to use a DPCO 24v relay and use the +/- 12v rails. Modern relays only take about 6mA so it shouldn't be a problem.


GSSL Relay using EAO Switch Thread
« Reply #3 on: August 17, 2007, 03:43:43 AM »
best place to take relay power is the unregulated supply voltages, from the rectifier + and -

the 78L/79Lxx tends to get too hot if loaded more.

Jakob E.
..note to self: don't let Harman run your company..


GSSL Relay using EAO Switch Thread
« Reply #4 on: August 17, 2007, 05:45:59 AM »
Heres my notes. Maybe of use or confuse you more:?


stripboard layout

Think the stipboard layout is drawn as viewed from underside.
The voltage after my rectifier was about 21V, but this was enough for the relays.
I don't think i needed R and C on mine


GSSL Relay using EAO Switch Thread
« Reply #5 on: August 17, 2007, 06:37:15 AM »
I've build several GSSL's with relay bypass. I used to tap AC power from one of the secondaries for the separate relay power supply (basicly the +15v-0v half of the gssl power supply) but somehow I always got some hum this way.
For me the solution was  to make a separate power supply for the GSSL itself like Matta dit in this thread..

This  way I could  just use the regulated  +15 v for my relays without getting any hum.
There are some nice relay bypass boards for sale on the black market which are perfect for a so called "hard Bypass"

When you go for this "Hard Bypass" option you can just solder jumpers on the GSSL control board so that it is in the "IN" state.
I prefer this way because the signal dos not travel through the GSSL circuitry when in bypass mode.
"Knowing that you are dreaming, however, does not automatically guarantee full rationality.
Then again, being awake doesn't ensure good thinking, either." -  Lynne Levitan

Siegfried Meier

GSSL Relay using EAO Switch Thread
« Reply #6 on: August 25, 2007, 12:40:42 AM »
Does anyone have a PDF of a PCB overlay to build one of these relay boards?  It would be nice to get a bunch of these going.  Enough to power 2 switches, Bypass and External Sidechain or main power etc.

Any thoughts?



GSSL Relay using EAO Switch Thread
« Reply #7 on: August 25, 2007, 01:23:28 AM »
I have a somewhat unrelated question about momentary switches...
Can a single pole switch switch several relays?
"All PCB traces are curved to emulate the electrical response of point-to-point wiring" -Drip


Related Topics

  Subject / Started by Replies Last post
2 Replies
Last post January 24, 2006, 05:48:51 PM
by coralsnd
16 Replies
Last post May 29, 2009, 08:20:41 AM
by barclaycon
0 Replies
Last post May 31, 2020, 06:15:51 PM
by ilfungo
4 Replies
Last post June 18, 2020, 03:13:55 AM
by [silent:arts]