LED in expression pedal powered from AX8

L

Lecchu

Inspired
Can I power the LED from EXP inputs of AX8?
Example is on picture: i ask about "green" lines. I would like to take +5V and GND from EXP1 (from thisame lines, witch is powered potentiometr) and via DPDT switch (and resistor) connect to "low power" LED. It is possible? EXP inputs in AX8 are provided for giving few miliApers?

This pedal is for wah. EXP1 input is continues, EXP2 is latched. In AX8 block wah has: on-off state connected to EXP 2 (latched), filter position (pedal position) = EXP 1 (continues). In this settings I dont have wah state on AX8 screen - and I thought it would be cool to show thise state with LED (located on the pedal case).
 

Attachments

  • pedal.jpg
    pedal.jpg
    628.1 KB · Views: 62
I'm not sure if this can be done, but I accomplished a similar goal by putting a 9V battery box in my Mission pedal, and connecting it like you show here. I drilled a hole in the bottom plate to turn the battery switch on/off. In case your answer turns out to be no, this is another way. Driving just the LED, the battery seems to last forever.
 
Yes, I thought about the battery, but before I preferred to ask about the possibility of power from AX8.

I will wait a moment, maybe someone from Fractal will reply ;)
 
The site you have linked show diode on voltage 3,2-3,4V (and take 20mA). For 5V (voltage from AX8) resistor ~85Ohm (=1,7V / 20mA) is required.

My question is not how to make this connection for LED (I'm an educated electronics), only if AX8 is prepared to take from EXP inputs a few extra mA (eg 10-20mA).
 
Lecchu said:
My question is not how to make this connection for LED (I'm an educated electronics), only if AX8 is prepared to take from EXP inputs a few extra mA (eg 10-20mA).
Click to expand...
That's a question for Fractal support. It's not published in the manual.
 
Lecchu said:
The site you have linked show diode on voltage 3,2-3,4V (and take 20mA). For 5V (voltage from AX8) resistor ~85Ohm (=1,7V / 20mA) is required.

My question is not how to make this connection for LED (I'm an educated electronics), only if AX8 is prepared to take from EXP inputs a few extra mA (eg 10-20mA).
Click to expand...
The resistor would be there to limit current not voltage... but since my guessing is the AX8 is not able to provide 20 or even 10mA you do better omit it. The led I posted is the only one that works, it will not be insanely bright but just bright enough. No problem running a 3V led at 5V at reduced current and no harm to the AX8 either. Maybe someone from Fractal support can chime in and confirm it
 
Enzo Sutera said:
No problem running a 3V led at 5V at reduced current and no harm to the AX8 either.
Click to expand...
Not sure how well that will work. With no resistor, the LED will drop the source voltage to its own forward voltage, which is well under 5V. In the process, It will demand every drop of current that the source can physically deliver.
 
Last edited:
I did this with a latching footswitch before, i used a trs cable, clear led and 220 ohm resistor, works fine , it's not so really bright but just bright enough, i tested it with the ext pedal as a latching switch and it worked like a charm.

I'm not an engineer nor affiliated with fractal so I'm not advising nor encouraging you to do this, i don't know if it can cause any issues internally and damage your equipment in the long term, do it at your own risk.


IMG_4197.JPG
 
There's probably current limiting built into the expression pedal output since it can be shorted with a switch, but the voltage drop across the LED might interfere with the calibration range of an expression pedal. I'd contact support to get their input. Safer bet would be to wire in an external supply or battery for the LED. With the small current draw of a single LED, a 9V battery should last a pretty long time.
 
g66 supports answer me, that battery is better idea.
To fractal support i can't write, becasue I bought AX8 in Europe (and support is provide form me by g66)
 
You must log in or register to reply here.
Back
Top Bottom