Circuit to pulse along with your playing/Tremolo circuit question

[KerryF]

Anyone have, or can draw up a schematic for a circuit that has an LED to pulse along with your playing.  Like if you play soft it pulses softer with the LED lighting up everytime you hit a note, and brighter when you play harder along with your playing.

Another question: With Opto Tremolos, how are the LEDs made to light.  I am trying to make something that needs the LED/LDR setup to create a tremolo type effect.  Can someone help me with the basic idea of the part that will do these things.

Thanks,
Kerry

[Harry]

Speaking straight from the horse's butt:
I'm pretty sure a strong booster followed by a high efficiency LED as a "clipping diode" will light when clipping. Then I guess you could use the boosters gain as a sensitivity control.
With tremolos there is LFO (low frequency oscillator) circuit that creates a wavering voltage, thus lighting and snuffing the led in turn.

[GibsonGM]

You'd have to watch out for any ckt you add to your signal chain to be sure it doesn't suck your tone away, 1-800.   Neat idea with the right approach.  I've seen a couple of ideas, search on Google.

I made a trem using a LM555 set up to flash an LED, coupled to a LDR right in the signal path - wrapped them together with tubing.  It worked pretty well for a simple square wave oscillator. Usually a sine-ish wave osc is used, or even triangle wave based on the LDR's response. 

[KerryF]

Gibson, can you maybe PM me a draw up of the schematic for the 555 creating lighting into an LDR.  I tried to start something like this for the circuit, but realized that I didnt have any idea of where to start.  I just need to see a type of example, and yours sounds like its what I need to see.  I have looked at the Tremulous Bear schematic, but I just cant figure it out from that.

Thanks

[JimRayden]

Speaking straight from the horse's butt:
I'm pretty sure a strong booster followed by a high efficiency LED as a "clipping diode" will light when clipping. Then I guess you could use the boosters gain as a sensitivity control.
With tremolos there is LFO (low frequency oscillator) circuit that creates a wavering voltage, thus lighting and snuffing the led in turn.

I think 1800 was talking 'bout controlling the amplitude of the tremolo with an envelope follower. Which I know has been done but can't recall the circuit's name for the schematic.

----------
Jimbo

[Seljer]

heres a nice page on the workings of the 555 timer http://www.uoguelph.ca/~antoon/gadgets/555/555.html
heres another page with a bunch of calcutors for frequency and duty cycle: http://home.cogeco.ca/~rpaisley4/LM555.html (you want an astable oscilaltor)


and theres a circuit for a tremolo with envelope controlled depth somewhere towards the top of the main geofex page

[KerryF]

Thanks Seljer.  The first link is what I have been going to a lot to check learn about the 555.

On the second link I found this: http://www.falstad.com/circuit/ex-555.html .  It shows an animated diagram of what happens.  Would this be a good place to start with for this circuit for the LFO section?

[d95err]

Another question: With Opto Tremolos, how are the LEDs made to light.  I am trying to make something that needs the LED/LDR setup to create a tremolo type effect.  Can someone help me with the basic idea of the part that will do these things.

LEDs are lit by applying positive voltage to the anode, relative to the cathode...   
(Sorry, I don't understand completely what it is you are asking, could you explain further?)

[KerryF]

^- I know, but what I am trying to do is to create a pulsing LED.

[KerryF]

If you go to the link I posted before: http://www.falstad.com/circuit/ex-555.html

Well if you go to where the "out" is, connect the + of the LED to that, and then a Ground symbol to the bottom (you can add parts and symbols by right clicking).  Now the LED is flashing at the speeds that the timer sets.  You can put a variable resistor pot in the place of one of the 10k resistors to change the speed.

Now that I have all that figured out... were would the "in" of the circuit go? (I know theres more to the circuit).

EDIT: Heres the code to enter to get the circuit I was saying.

Code Select Expand

$ 1 5.0E-6 5.5784190371800815 64 7.0 50
165 208 80 224 80 0 0.0
w 208 112 176 112 0
r 176 112 176 176 0 10000.0
w 176 176 208 176 0
w 176 176 176 208 0
w 176 208 208 208 0
c 176 208 176 272 0 3.0E-7 4.257964891509618
g 176 272 176 288 0
r 176 112 176 48 0 10000.0
w 176 48 272 48 0
R 176 48 112 48 0 0 40.0 9.0 0.0
O 336 144 400 144 0
162 336 144 336 272 0 1.0 0.0 0.0
g 336 272 336 288 0
o 6 32 0 3 10.0 0.0015625 0
o 11 32 0 10 10.0 9.765625E-5 1
Go to the site I linked above, right click inside the black area, click file, click import, and paste the code into it.

Another code for the LED lighting opposite of when the signal pulses out:

Code Select Expand

$ 1 5.0E-6 6.01975421667673 64 7.0 50
165 208 80 224 80 0 0.0
w 208 112 176 112 0
r 176 112 176 176 0 10000.0
w 176 176 208 176 0
w 176 176 176 208 0
w 176 208 208 208 0
c 176 208 176 272 0 3.0E-7 3.6788644905435137
g 176 272 176 288 0
r 176 112 176 48 0 10000.0
w 176 48 272 48 0
R 176 48 112 48 0 0 40.0 9.0 0.0
162 336 144 336 272 0 1.0 0.0 0.0
g 336 272 336 288 0
w 336 144 400 144 0
t 400 144 432 144 0 1 -8.999999995 0.0
g 432 160 432 288 0
r 432 128 432 48 0 50000.0
w 432 48 272 48 0
O 432 128 480 128 0
o 6 32 0 3 10.0 0.0015625 0

[rockgardenlove]

I've never looked at a SS tremolo with an optocoupler, but I've looked at many tube amps with trem.
http://www.ampwares.com/ffg/schem/bandmaster_ab763_schem.gif
In the Fender Bandmaster it's pretty easy to see.

[KerryF]

So wheres the in?

And heres another idea of a randomish pulse.  Would ctl (control pin) be the in?:

Code Select Expand

$ 1 5.0E-6 10.391409633455755 53 5.0 50
165 176 96 192 96 0 9.0
R 240 64 240 48 0 0 40.0 9.0 0.0
R 240 256 240 304 0 3 20.0 2.0 3.0
O 304 160 352 160 0
w 176 128 144 128 0
r 144 128 144 64 0 1300.0
w 144 224 176 224 0
c 144 224 144 272 0 3.0E-6 3.1325894042419966
g 144 272 144 288 0
w 144 192 144 224 0
w 144 192 176 192 0
r 144 128 144 192 0 300.0
w 144 64 240 64 0
162 304 160 304 272 0 1.0 0.0 0.0
g 304 272 304 288 0
o 2 32 0 6 5.0 7.8125E-4 0
o 3 32 0 6 10.0 9.765625E-5 0

[JimRayden]

You'll be needing an envelope follower to control that 555 circuit in any way:

http://www.diystompboxes.com/smfforum/index.php?topic=37679.0

---------
Jimbo