Negative/Polar/Inverted LED's

[jdom1984]

Hi I am not sure exactly how to phrase what I want.

When one led gets more current I want another to get less.

That is as simple as I can phrase it.

I am new to all of this and its all a learning curve. I have looked into transistors a little and it seems maybe I can use one to control the current of another? Or will it simple turn the other LED on and off?

I am making a pedal called satans anus. I want his eyes to light up when the pedal is turned on but when a signal comes through it dims his eyes and lights up his anus. So there should be a dancing effect between the two different colours depending on how loud the signal is that you are playing through it.

I don't mind if it means that the signal splits off and has to enter its own little circuit to control this aspect. As long as its super simple..

I connected a LED straight from the BIAS knob I have and it was lighting up when a signal was playing which was working well. But it also seems to suck current from the signal and makes the overall volume considerably less. It might even effect the amount of fuzz/gain/distortion in the signal. I want my pedal to be as loud and dirty sounding as possible so I would like a better solution.

I have managed to add 6 pots and it is a great pedal already just want to add the finishing touches.

Many thanks for any ideas on how to get the LED's to light how I want.

Regards. Dom.

[Kevin Mitchell]

Hi, Dom. A schematic would be very useful.

-KM

[~arph]

Ah the old fiery anus mod... 

What you need is an envelope follower (something like the nurse quacy is good) for lighting up the exit hole, and put in inverter on the envelope (either an opamp, or a BJT (PNP) ) to have an opposing signal for the eyes.
This way when there is no signals the eyes will be lit and when there is the light takes a different route 

[deadastronaut]

I am making a pedal called satans anus. I want his eyes to light up when the pedal is turned on but when a signal comes through it dims his eyes and lights up his anus.

this made my day ha ha... cant wait to see a demo. 

[jdom1984]

Hi, Dom. A schematic would be very useful.

-KM

Hi I a, following a pretty basic fuzz face style but I have made some serious altercations. I am at a prototype stage and nearly ready to put it in a enclosure. I will be tweaking it more on a breadboard before doing this.

I will be writing down the schematic once I have fully decided on it. So I can easily re create it.

[jdom1984]

Ah the old fiery anus mod... 

What you need is an envelope follower (something like the nurse quacy is good) for lighting up the exit hole, and put in inverter on the envelope (either an opamp, or a BJT (PNP) ) to have an opposing signal for the eyes.
This way when there is no signals the eyes will be lit and when there is the light takes a different route 

Ah ok that sounds exactly what i need. Any schematics or links to make that clearer for me?

I wil research into it more now you have given me the scent.

[jdom1984]

I am making a pedal called satans anus. I want his eyes to light up when the pedal is turned on but when a signal comes through it dims his eyes and lights up his anus.

this made my day ha ha... cant wait to see a demo. 

thanks I know you from some pcb's I was looking at on Ebay! Hi! Thanks for the comment I might be one of your customers soon! ;-)

[merlinb]

If the signal is large enough (e.g. after being amplified by your FX circuit) then something like this might suit:

It needs about 1V peak to trigger, so you can't plug your guitar directly into this since the guita signal is normally less than 0.1V peak.

[Fancy Lime]

Hi I a, following a pretty basic fuzz face style but I have made some serious altercations.

Yeah, I bet fiddling with Satan's anus might lead to some serious altercations... You are killing me.
Side note: "Serious Altercations with Satan's Anus" is also a great album title for a grind core band.

If I were you, I would try something like this:



The input (all the way to the left) can come from the pedal input or output. None of the components should be critical, NPN transistors can be almost any you happen to have in surplus. The current limiting resistors (2k-20k) need to be adjusted to fit the diodes you use (bright diodes can use higher resistance). Start with 22k or something and go down until you have the desired brightness. Start the adjustment with the upper resistor before going to the lower.

Disclaimer: I did not test this, just pulled it from where the LED is off when there is no signal. Should work though, as it is essentially a very much simplified version of a kind of rectifier that is used in many classic compressors (DOD, Ross...). Some values may need tweaking for optimum performance.

EDIT: I just saw that my schematic has an error in it:
The upper end of the 22u cap and the two "eye" LEDs should go between the upper 2k-20k resistor and the "rear eye" diode instead of between that diode and the transistor.
I also forgot to mention: this is actually functionally quite similar to Merlins solution. The biggest difference are:
1) The gain stage in my version. You could also add that to the front of Merlins version if you like. Doing that you probably get the most versatile option.
2) Merlins version has a separate transistor as a current source for the two "eye" LEDs, and will therefore work with pretty much any LEDs, whereas in my version the current through the "eye" LEDs is "passively sourced from the bottom of the upper resistor floating up towards +9V when the transistor is closed. My version may therefor only work (well) with LEDs that do not need too much current to light up brightly.

Cheers and happy fiddling,
Andy

[EBK]

fiddling with Satan's anus

That sounds like a very messed up version of The Devil Went Down to Georgia. 

[Fancy Lime]

fiddling with Satan's anus

That sounds like a very messed up version of The Devil Went Down to Georgia. 

I thought the messed up version of that just changes the "to" to "on", no?

EDIT: No wait, I was thinking of the R-rated version.

[MrStab]

"Serious Altercations with Satan's Anus"

tag a friend and say nothing

[PRR]

> my schematic has an error

[Rixen]

..and a long tail pair version.. note the signal in to D1 will shift the LED brightness as it crosses over the 1/2 Vcc threshold set by R4/R5. You can also tailor the threshold by adjusting the R4/R5 ratio..




edit-Vcc is assumed to be switched by the footswitch
edit2- I have the Eyes and Anus LED's in the wrong legs...

[duck_arse]

edit2- I have the Eyes and Anus LED's in the wrong legs...

this.

[MrStab]

[jdom1984]

wow what a highly entertaining read and I learned something!! Without fiddling with satans anus!

:-)

hahaha

Cool guys thanks for those schematics. I was hoping for something much more simple, literally a few components at the most... Just two transistors one is feeding the anus led and the other is to suppress the eyes led when the first one is working... Can't I just hook um up to do that? kinda feeding straight into eachother?

I need to read more about how they work but I know there are two ways they work one is an amplifier and the other a switch. But can the switch not only be in an on and off state and be more analogue than digital?

thanks guys..

I will keep at it soon. I have been writing down my schematic. I will probably make a new thread to unveil satan's anus for all the world to see. But I think i will get some technical advice that will improve it. I actually went a step back and am loosing some bias and the very low bass cuts out sometimes.. Fiddling with 9v input resistor probably didnt help...
If its too complex and time consuming I will give up on the fancy idea.. I know I can always get the anus light from the BIAS pot I have but as I said it lowers the volume of the entire circuit.

[jdom1984]

really there are brown leds??? hahah...

[PRR]

really there are brown leds??? hahah...

Did you read the notice in pink?

"Sorry, 'brown' did not return any results."

However Black (dark emitting, DED) LEDs are easy. Hook a light emitting diode direct to a large battery, boom, now it only emits darkness.

[merlinb]

I was hoping for something much more simple, literally a few components at the most... Just two transistors one is feeding the anus led and the other is to suppress the eyes led when the first one is working... Can't I just hook um up to do that? kinda feeding straight into eachother?

Er.. you've been given three circuits that do exactly that... two transistors and a few resistors...