So anyone else notice LDR's popping up everywhere?

[BillyJ]

I saw that box at effetor13 and I think I saw either Colin or Ansil with a mod for somethign using one.
So....how and when can these be used to good effect.
I am guessing anywhere you might want variable resistance right?
Jeeze I could just seee me with a box with a whole mess of these and switches on it....LOL!
Anyway I think I might try to use one on my uglyface.
Could I just put an LDR on top and have it switch from the place where the LDR/LED combo is? Then I could control the envelope with my foot right?
Well anyway I have started toi see these crop up but no talk about it so I thought it might be a cool subject to bring up.

[petemoore]

Trying to figure out how one could make a Tremolo using LDR as the variable resistor.
 I'm sure it's been looked at or done {EZ Vibe Mod?]\
 Just the LDR part ... is there a way to make an LDRs variable resistance
vary resistance to the signal path and make an effective [if limited] Tremolo?
 ie volume change controlled by the lumens changes [light/dark] 'seen' at the LDR?

[mattv]

The 4ms Tremulus Lune uses an LDR/LED for the tremolo.

LDRs are fun.

[smoguzbenjamin]

I think an LDR would be really cool to control filter sweep :mrgreen: Aren't LDR's also called photo-transistors? :?

[travissk]

photoresistors perhaps?

[smoguzbenjamin]

I donno I got an old electronics kit from the 70's which I could pluck good bits out of. Not much there but there was a LED-like object which they called a phototransistor and it basically was an LDR. It was drawn like a transistor but then with light arrows pointing at the base... :? Wierd...

[mattv]

There are infrared devices like what you speak of. This is probably what is being referred to. Although LEDs apparently have a photovoltaic quality that reacts to light. In this case though, they certainly aren't drawn like transistors.

Tim Escobedo's idiot wah (or whatever it's called) offers an LDR as the Variable resistance of the filter. I tell you, I probably looked real cool with that flashlight in my mouth (while playing guitar) after building it.  :wink:

[Ansil]

i did the mod to the hollis compressor.  i also added the same thing to the judas pedal. i used an ldr to create a capcophony of noise.  and i used one in a feedbacker pedal.

[smoguzbenjamin]

Could have been IR. Actually I'm damn sure of it being IR because there was an IR LED that came with the package, but I couldn't find it

I'm going to buy some LDRs!

[Transmogrifox]

There IS a difference between LDRs and phototransistors.  Phototransistors are not going to give a variable resistance, merely a light dependent transconductance, so you could create a tremolo effect by modulating an LED with your guitar signal, then put a mechanically controlled light filter in front of the LED and put the phototransistor on the other side so the light filter controls the amount of light that gets through to the phototranny.

An LDR is not used as an amplification device.  These are often used as light sensors, such as the sensor that gives the signal to turn on the street lights when it gets dark...

LDRs are what you want to use for modulating filter and tremolo effects.  These ARE used in many circuits such as a DOD compressor, Small Bear's Tremulus Bear, some filter FX etc..

[ExpAnonColin]

LDRs are very simple, very controllable, and when you don't want it to be a perfect, fast, square wave, they're very very useful.  I don't think Tim even knows what an LDR is.  The tremolo pedal he's using mostly uses caps and transistors.  The ability to convert voltage to resistance is incredibly useful... it's very simple once you understand it, too.  I'm working on a pretty complex LDR based tremolo.  I mean, the concept is simple, and it has tons of applications, so why not?

I think you were talking about my LDR based envelope control for the frequency analyzer.

-Colin

[BillyJ]

Yep that it!!!    
I saw that and another pedal (Doug Deepers at effector13 I think) on the same day and I began to wonder why I didn't see these more often.
I guess it would react differently in different light situations?
Gonna have to look for useful places to try this.
Fun idea. Hope no one minds if I nake it for use with my own pedals.

[smoguzbenjamin]

I was wondering, If I used an LDR on the outside of an envelope filter and had a mode selector switch between envelope and LDR, then I could in principle control the wah with my foot. But what about ambient light? :?

[Arno van der Heijden]

I was wondering, If I used an LDR on the outside of an envelope filter and had a mode selector switch between envelope and LDR, then I could in principle control the wah with my foot. But what about ambient light?

Lovetone has exactly this option on some of their pedals. A ldr mounted on a jack plug can be inserted into the input for the expression pedal.

[gez]

LDRs are for softies!  What I've always fancied doing is using the treadle of a wah to control the flame on a blow torch, use this to control a heat sensor rigged up to a filter and you've got one hell of a stage show!...er, I mean wah...I need to lie down now.

[BillyJ]

Gez man that is too flippin funny!!!...Uh your kidding tho....uh right?!?

Arno, that is aweseom man thanks for sharing that! I think sounds like a great thing to try. My friend has a BlackCat RM he just got but no expression pedal. I am gonna make him one...very cool!!!

[gez]

Gez man that is too flippin funny!!!...Uh your kidding tho....uh right?!?

One pair of singed sequin-studded flares says not!  :shock:

[smoguzbenjamin]

Sounds like I'll be making an envelope filter with ldr control then. But I'm still wondering if ambient light will affect it. I want to wave my foot over the pedal and make it wah that way :twisted: Sounds really cool to me, but my mind keeps screaming "BUT WHAT ABOUT AMBIENT LIGHT!!". :? Anyone have any prior experience?

[BillyJ]

I'm assuming ambient light is what it is all about. Different light, different response.
Put it on a switch and don't expect it to work as great as a rocker  :wink:
You might try putting a lamp near/over it. That might help to create a somewhat more reproducable thing out of it.
I am thinkoing of using them in places where it iwll just mess the sound up. I'm not gonna shoot for any real great control over things. Then again I have never used them outside a box so I am all guesses here.
Even without super control I think they could be a lot of fun..

[smoguzbenjamin]

Yeah, It'll be an EF with switchable modes Or maybe 2 LDRs that react differently to ambient light like one for darker rooms and one for lit-up rooms. And of course simple Envelope Control. Or maybe a 3-way mode switch, LFO controlled, Envelope controlled and LDR controlled.

Whoah. Too many options :twisted: