GSSL add-on help thread

[Harpo]

For the colour coding of Your transformer (these are not standarized between different manufacturers), yes. The red/orange junction will be your 0V reference voltage. This will also connect to always connected safety ground in one single spot, except you make this connection switchable for a ground-lift.
Black and blue are your transformers secondary outer winding ends. A transformer transforms AC (alternating current) in to AC out at its specific winding ratio. Positive and negative alternates at your local 50/60 Hz mains frequency.

 

[MiamiBoy]

Thanks Harpo, for explaining it to me in details.

When I measured with my DMM, the black with 0 and blue with 0,
I remember both outputted 18VAC each, but I couldn't see which was positive and which was negative.
Because I noticed in the "CRC manual", it says that the output has a positive and negative side, that goes to mainboard.
So I wanted to be carefull and not wire the output from CRC opposite into my GSSL. That's all.

But okay, there's no difference between pos / neg wire output from the secondaries when connecting directly to main PCB or having a CRC in between those.

 

[MiamiBoy]

Is the 7812 regulator an add-on?

When is the 7812 necessary vs. unnecessary?
I didn't get it in my kit, from PcbGrinder.

 

[Script]

It's an auxiliary for relays (e.g. hard bypass) and LEDs, I'd think

 

[steve_savage]

Hi, 1st time post!

I’ve built a GSSL using the rev7 pcbs. All works great, but would like to add in a pair of output transforms.
I see the nekotronics clone used carnhill vtb2281 600/600r.
But I’m unsure where the correct place would be to take the output from.
Or will it be simply from before the output xlr wiring?

Thanks in advance!
(Apologies if this is in the wrong thread!)

 

[gyraf]

yep, simply at the output wireing

 

[steve_savage]

yep, simply at the output wireing

Excellent, many thanks!

And the 600R transformers would be fine for this PCB?

 

[gyraf]

yes, should be.

If you loose low end, short the 100R output resistors or make them e.g. 22R

/Jakob E.

 

[steve_savage]

yes, should be.

If you loose low end, short the 100R output resistors or make them e.g. 22R

/Jakob E.

I’ve fitted the transformers and they have added some nice colour. What would the effect of changing the output resistor have?

One other thing, is there a simple ‘how to ‘ on calibration for the Gssl?

 

[MiamiBoy]

Got these 2V push-buttons for bypass & turbo. And a meter with 5-7V LED.
So I have 9-11 volts in total and I wanna connect it to the 12V I have available on the ctrl-board-LED output.

How can I add them in parallel without dimming the meter-LED whenever buttons are pushed down?

 

[Harpo]

Got these 2V push-buttons for bypass & turbo. And a meter with 5-7V LED.
So I have 9-11 volts in total and I wanna connect it to the 12V I have available on the ctrl-board-LED output.

How can I add them in parallel without dimming the meter-LED whenever buttons are pushed down?

You don't have the LED's inside the DPDT switches connected in series, so LED forward voltages don't add up to your '9-11 volts'.
Allowing maybe 10mA per LED inside the switches for a parallel connection, each LED needs a current limiting resistor of (12VDC supply - 2VDC LED forward voltage)/0.01A= 1000 ohms.
Inside the meter are two series connected LEDs with -depending on LED-colour- 5-7VDC forward voltage. Assuming maybe similar brightness and again allowing 10mA, the current limiting resistor for your meter illumination will be (12VDC supply - maybe 5.7VDC LED forward voltage)/0.01A= 630 ohms. Lesser allowed mA=lesser brightness, exceeding the max allowed 20mA parts limit will let the smoke out.
You DON'T connect these to the 12VDC spot on control pcb. The 78L12 vreg isn't build for this additional load.
You connect to the optional 12VDC aux supply spot on main pcb (and without the 7812 voltage regulator installed, there is no aux 12VDC).
The LEDs inside the switches only use the switch housing as a carrier. If these are illuminating or not has nothing to do with the switches status (they could be rhythmical blinking or show an overload condition or whatever else), except you hook these up accordingly. For your bypass switch you'd need 2 switch poles for the gssl-circuit and a 3rd pole for powering the LED. The switch only has 2 poles, so you'd probably use an additional DPDT relay for the else missing pole. The supersidechain filterboard already has a provision for this relay and protection diode on board, else a piece of perfboard, apropriate relay and diode will do as well.
Good luck
(must have been answerd a LOT more than 10 times...)

 

[MiamiBoy]

You don't have the LED's inside the DPDT switches connected in series, so LED forward voltages don't add up to your '9-11 volts'.
Allowing maybe 10mA per LED inside the switches for a parallel connection, each LED needs a current limiting resistor of (12VDC supply - 2VDC LED forward voltage)/0.01A= 1000 ohms.
Inside the meter are two series connected LEDs with -depending on LED-colour- 5-7VDC forward voltage. Assuming maybe similar brightness and again allowing 10mA, the current limiting resistor for your meter illumination will be (12VDC supply - maybe 5.7VDC LED forward voltage)/0.01A= 630 ohms. Lesser allowed mA=lesser brightness, exceeding the max allowed 20mA parts limit will let the smoke out.
You DON'T connect these to the 12VDC spot on control pcb. The 78L12 vreg isn't build for this additional load.
You connect to the optional 12VDC aux supply spot on main pcb (and without the 7812 voltage regulator installed, there is no aux 12VDC).
The LEDs inside the switches only use the switch housing as a carrier. If these are illuminating or not has nothing to do with the switches status (they could be rhythmical blinking or show an overload condition or whatever else), except you hook these up accordingly. For your bypass switch you'd need 2 switch poles for the gssl-circuit and a 3rd pole for powering the LED. The switch only has 2 poles, so you'd probably use an additional DPDT relay for the else missing pole. The supersidechain filterboard already has a provision for this relay and protection diode on board, else a piece of perfboard, apropriate relay and diode will do as well.
Good luck
(must have been answered a LOT more than 10 times...)

Great detailed explanation. Thanks Harpo. Believe me, I tried to find this info -no luck. I've been searching for days!

I'll order one 7812 and connect the meter-LED's to the aux, thanks.
The meter has an internal 600Ω resistance and I believe the LED's are drawing 20mA.
So I'm not sure if a resistor is needed or not. We'll see, I can start with one and pull it off to see if anything changes.

I'm gonna built 2x SSC-boards soon, so I'll hook up my pushbutton-LED's to them (and maybe with a 1K resistor to each, if needed.
Not completely sure about the Amps.. the websites says max current 3A which seems odd !?

Thank you so much for helping me solve & understand all these challenges.. I've learned a lot, really!