Hello after doing the little angel chorus, I thought of making one, also using the PT2399, but with a sinusaidal wave generator on the LFO. The result was this, a warm chorus on a PCB no longer easy to do and with very few components.
NOTES:
* depth control can be 250k or 500k, the higher value, the lower the effect attack.
* R19 is the resistance responsible for controlling the delay time of chorus, you can put a 5k potentiometer in series with R19 to have a time control.
* Speed control depends on C1, C2, C3 and R2. Enlarging the three capacitor or the resistance we can get slower repetitions, achieved in configuration C1 = C2 = C3 = 470nf and R2 = 100k have a balance between fast and low speeds.
* 78L05 voltage regulator is invested in the circuit because it had not as a component in the libraries of the eagle, but is the correct posisicion Layout.
(http://s1d3.turboimagehost.com/t1/6694521_PCB_del_chorizo.png) (http://www.turboimagehost.com/p/6694521/PCB_del_chorizo.png.html)
(http://s1d3.turboimagehost.com/t1/6694522_circuito_del_chorizo.png) (http://www.turboimagehost.com/p/6694522/circuito_del_chorizo.png.html)
Downloas PCB http://www.mediafire.com/?c3yap3cqj01yp56
Nice circuit! ;D
Can the remaining section of the opamp be used for a small tonestack?
You got some sound clips?
BTW-I love chorizo!
So the only major difference is the LFO, right? It looks like everthing else is the same.
Also, shouldn't that last opamp be stabilized if it isn't used? Tie 13 to 14 and 12 to ground?
Quote from: chi_boy on April 03, 2011, 09:05:51 PM
So the only major difference is the LFO, right? It looks like everthing else is the same.
Also, shouldn't that last opamp be stabilized if it isn't used? Tie 13 to 14 and 12 to ground?
The PT2399 section is a standard configuration, so the only part to change is the LFO.
Tie 13 to 14 and 12 to ground is easy to do, but leaving them in the air does not cause problems.
Nice upgrade! Would be nice to use the spare opamp as an output buffer. Soundclips?
Quote from: chi_boy on April 03, 2011, 09:05:51 PM
Also, shouldn't that last opamp be stabilized if it isn't used? Tie 13 to 14 and 12 to ground?
Yikes, don't do that or you risk burning the thing out! To properly stabilise an unused opamp you should connect the + input to a suitable reference (e.g. Vbias) and connect the - input to the output (i.e., set up as a voltage follower).
Also, if you arranged the input opamp as a
non-inverting gain stage you could get higher input impedance
and much less noise :)
Very nice - I also like bife chorizo!!!
Quote from: merlinb on April 04, 2011, 05:16:22 AM
Quote from: chi_boy on April 03, 2011, 09:05:51 PM
Also, shouldn't that last opamp be stabilized if it isn't used? Tie 13 to 14 and 12 to ground?
Yikes, don't do that or you risk burning the thing out! To properly stabilise an unused opamp you should connect the + input to a suitable reference (e.g. Vbias) and connect the - input to the output (i.e., set up as a voltage follower).
Also, if you arranged the input opamp as a non-inverting gain stage you could get higher input impedance and much less noise :)
Well that stinks. I researched a while back and concluded that it had to go to ground. I did a layout based on that information. I didn't etch the board yet so no real loss, but I think that may really mess up my layout.
Quote from: chi_boy on April 04, 2011, 02:41:43 PM
Quote from: merlinb on April 04, 2011, 05:16:22 AM
Quote from: chi_boy on April 03, 2011, 09:05:51 PM
Also, shouldn't that last opamp be stabilized if it isn't used? Tie 13 to 14 and 12 to ground?
Yikes, don't do that or you risk burning the thing out! To properly stabilise an unused opamp you should connect the + input to a suitable reference (e.g. Vbias) and connect the - input to the output (i.e., set up as a voltage follower).
Also, if you arranged the input opamp as a non-inverting gain stage you could get higher input impedance and much less noise :)
Well that stinks. I researched a while back and concluded that it had to go to ground. I did a layout based on that information. I didn't etch the board yet so no real loss, but I think that may really mess up my layout.
probably you read "ground" right, but it would be ground from dual supply +/-. For a single supply configuration, that actually means a mid voltage. The point is to avoid the output to go to the rails
Interestingly the idea of using the last section of the TL074 as a buffer but I manter the plate as simple and small as possible.
The effect works well, soon I'll upload some sound clips. Will not regret making this chorus
Looks interesting ;D
Might I add a few suggestions?:
1) Connect the unused lug of the 250K pot to the wiper. A generally good idea.
2) Add a polarity protection diode somewhere in the circuit.
Might try this out in the future. Gonna wait a bit until this levels out ;)
Quote from: chi_boy on April 04, 2011, 02:41:43 PM
Well that stinks. I researched a while back and concluded that it had to go to ground. I did a layout based on that information. I didn't etch the board yet so no real loss, but I think that may really mess up my layout.
You can connect the + input to anything as long as it is within the normal limits of the opamp, i.e, between about 2V and 7V. Maybe there's some other PCB track passing by that has some DC bias on it?
Interesting circuit! I agree about the output buffer, I'm all about output buffers lately. I'll try to knock up a layout including using the other opamp as an output buffer.
Quote from: Barcode80 on April 04, 2011, 04:24:27 PM
Interesting circuit! I agree about the output buffer, I'm all about output buffers lately. I'll try to knock up a layout including using the other opamp as an output buffer.
Well, could modify the circuit and use that last opamp as buffer.
Quote from: Barcode80 on April 04, 2011, 04:24:27 PM
Interesting circuit! I agree about the output buffer, I'm all about output buffers lately. I'll try to knock up a layout including using the other opamp as an output buffer.
Well, could modify the circuit and use that last opamp as buffer.
and would have to do?
or use the opamp to invert the input, and then mix the delayed signal with either the positive or negative input, for a different flavour
i've done this with a phaser and is quite cool
I couldn't resist this - http://www.youtube.com/watch?v=TFSsJE2UhIU&feature=related
Quote from: merlinb on April 04, 2011, 04:17:20 PM
Quote from: chi_boy on April 04, 2011, 02:41:43 PM
Well that stinks. I researched a while back and concluded that it had to go to ground. I did a layout based on that information. I didn't etch the board yet so no real loss, but I think that may really mess up my layout.
You can connect the + input to anything as long as it is within the normal limits of the opamp, i.e, between about 2V and 7V. Maybe there's some other PCB track passing by that has some DC bias on it?
Turns out there are quite a few "opinions" about how to do this. After doing some more research, I did find this:
http://pdfserv.maxim-ic.com/en/an/AN1957.pdf (http://pdfserv.maxim-ic.com/en/an/AN1957.pdf)
This App Note clearly states that the best way is as you said.
As for my problem, I don't want to hijack. Wasn't my intent. I may opt to leave it though, primarily because it is a clone of the Barber Dirty Bomb and that is the way it was traced.
Regarding your suggestion for DC Bias, what would I be looking for?
The schematic in on the "Other" forum if you care to look. The layout there isn't current though. I would need to pick something up around IC1A. Taking anything from C & D totally blows my layout.
http://www.......org/viewtopic.php?f=7&t=5592&hilit=dirty+bomb&start=40#p134709 (//http:///viewtopic.php?f=7&t=5592&hilit=dirty+bomb&start=40#p134709)
Quote from: chi_boy on April 04, 2011, 10:29:02 PM
Regarding your suggestion for DC Bias, what would I be looking for?
Look for any trace sits between 2V and 7V, i.e., it is biased above ground. For example, you could connect pin 5 to pin 3 in your layout (I mean this one www.....org/download/file.php?id=11665&mode=view ), since that sits at 4.5V. That wouldn't spoil your ground plane under the IC. There is signal on pin 3 of course, but that doesn't matter since it is within the headroom of the opamp (it must be, since U1a has to handle the same signal!) All you're trying to do is turn unused opamps into buffers that don't go anywhere or feed anything.
I think the output impedance is relatively low, less than 10k. If so we would not need to place a buffer.
As polarity protection, I always use in my pedals a 1N4007 diode in series with the positive. I don't like the idea of putting it between the positive and negative.
Quote from: merlinb on April 05, 2011, 04:21:27 AM
Look for any trace sits between 2V and 7V, i.e., it is biased above ground. For example, you could connect pin 5 to pin 3 in your layout (I mean this one www.....org/download/file.php?id=11665&mode=view ), since that sits at 4.5V. That wouldn't spoil your ground plane under the IC. There is signal on pin 3 of course, but that doesn't matter since it is within the headroom of the op-amp (it must be, since U1a has to handle the same signal!) All you're trying to do is turn unused op-amps into buffers that don't go anywhere or feed anything.
Well, I learned a think or two with this one. Thanks for the training. It's great for the Dirty Bomb, but not so much for Chorizo. Both rails are easy to get to, but no bias voltage is close at hand. It looks like it would be a major rework to stabilize the op-amp the right way.
Quote from: ppaappoo on April 03, 2011, 02:05:38 PM
Hello after doing the little angel chorus, I thought of making one, also using the PT2399, but with a sinusaidal wave generator on the LFO. The result was this, a warm chorus on a PCB no longer easy to do and with very few components.
NOTES:
* depth control can be 250k or 500k, the higher value, the lower the effect attack.
* R19 is the resistance responsible for controlling the delay time of chorus, you can put a 5k potentiometer in series with R19 to have a time control.
* Speed control depends on C1, C2, C3 and R2. Enlarging the three capacitor or the resistance we can get slower repetitions, achieved in configuration C1 = C2 = C3 = 470nf and R2 = 100k have a balance between fast and low speeds.
* 78L05 voltage regulator is invested in the circuit because it had not as a component in the libraries of the eagle, but is the correct posisicion Layout.
(http://s1d3.turboimagehost.com/t1/6694521_PCB_del_chorizo.png) (http://www.turboimagehost.com/p/6694521/PCB_del_chorizo.png.html)
(http://s1d3.turboimagehost.com/t1/6694522_circuito_del_chorizo.png) (http://www.turboimagehost.com/p/6694522/circuito_del_chorizo.png.html)
Downloas PCB http://www.mediafire.com/?c3yap3cqj01yp56
Ppaappoo you are from Argentina?? I'm from Peru!!! you post this on Zonadiyer of Argentina??? I want to make this with the mod you suggested of adding a pot of 5k to control the tempo it is right??? you prove the pedal yet??? thank a lot it is a good work!!!
yes I'm the same, I've sent a PM!
HI, i have some questions about the buffer at the end.
the questions are in the image
(http://s1d2.turboimagehost.com/t1/6742993_hfhfhfhf.png) (http://www.turboimagehost.com/p/6742993/hfhfhfhf.png.html)
Yeah use the 5v as vref, connected to the bottom of R11. You'll also need a cap on the output of the opamp, and a 100k resistor to ground after it. As an alternative, you could consider a diff amp as the output stage.
You'd better avoid C4 and C12, enter with R10 and R16 in pin 13, R11 from pin 12 to vref and add a 10k between pin 13 and 14.
this way you'll have a better wet/dry mix and since ic1c and ic1d are inverter, you''ll get a proper in phase signal.
Better again you might add a filter cell on ic1c and a "restorer" on ic1d, to lower hiss... just 2 resistors and 2 caps
Quote from: Fender3D on April 08, 2011, 08:39:02 AM
You'd better avoid C4 and C12..
Shouldn't one stay? DCs at outputs of input buffer and PT2399 differ..
Btw. adding output mixer gives possibility to remove boost (2x) from input stage (=bigger dynamic range).
My (repeated) advice would be to turn input buffer into non-inverting buffer, it's IMO better noisewise and one or two resistors could disappear now (but fx would become inverting again).
Quote from: Fender3D on April 08, 2011, 08:39:02 AM
Better again you might add a filter cell on ic1c and a "restorer" on ic1d, to lower hiss... just 2 resistors and 2 caps
Yep, pre/de-emphasis, IMO good idea.
And R17/R18 and R14/R15 pairs could be IMO merged into one resistor each - these "triangles" are leftovers from removed 2nd order LPF filtering :)
T.
Please somebody help adding a layout or a scheme whit the modifications proposed??
Quote from: GodSaveMetal on April 08, 2011, 10:20:06 AM
Please somebody help adding a layout or a scheme whit the modifications proposed??
OK, something like this (quick redraw of something of mine, I have not replaced all values by exact Chorizo ones, e.g. capacitors around PT2399):
(http://thmq.mysteria.cz/diystompboxes.com/chorizo_mods_thmq.gif)
RP1, RP2 and CP form pre-emphasis, CD and RD de-emphasis - if you don't want to use it, remove them all and replace RP1 by wire.
T.
I did the changes you suggest are good?
(http://s1d2.turboimagehost.com/t1/6754448_hhhhhhhhhhhhhh.png) (http://www.turboimagehost.com/p/6754448/hhhhhhhhhhhhhh.png.html)
Quote from: ppaappoo on April 08, 2011, 12:10:12 PM
I did the changes you suggest are good?
(http://s1d2.turboimagehost.com/t1/6754448_hhhhhhhhhhhhhh.png) (http://www.turboimagehost.com/p/6754448/hhhhhhhhhhhhhh.png.html)
Yes, you may just consider lowering impedances in mix/feedback networks (for less noise):
R8 = R10 = R16 = R23 = 10k
R22 = R24 = 2k2
C18 = C4 = 22nF
and bigger value for output cap for less low cut in some conditions:
C17 = 1uF
T.
well, thanks to Thomeeque this would be the final circuit. Thanks
(http://s1d2.turboimagehost.com/t1/6754597_hhhhhhhhhhhhhh.png) (http://www.turboimagehost.com/p/6754597/hhhhhhhhhhhhhh.png.html)
ups :icon_redface:
Quote from: ppaappoo on April 08, 2011, 12:36:15 PM
well, thanks to Thomeeque this would be the final circuit. Thanks
(http://s1d2.turboimagehost.com/t1/6754597_hhhhhhhhhhhhhh.png) (http://www.turboimagehost.com/p/6754597/hhhhhhhhhhhhhh.png.html)
Yep, perfect, just one small change yet I have forgot about above:
after "merging" resistors in PT2399 LPFs, values of feedback capacitors
C13 and C11 have to be adjusted to get same filtering curve from 1nF to
3.3nF (it should be 3-times bigger = 3nF exactly, but 3n3 is IMO close enough).
Good luck :) T.
Grr Thomas :icon_evil:
the symbol you have for PT2399 is cooler than mine..
I'll steal it for my library.... :icon_twisted:
Quote from: Fender3D on April 08, 2011, 01:12:33 PM
Grr Thomas :icon_evil:
the symbol you have for PT2399 is cooler than mine..
I'll steal it for my library.... :icon_twisted:
:icon_mrgreen:
Be my guest (http://thmq.mysteria.cz/eagle/thmq.lbr) :)
T.
thanks man,
for the sharing, but when I was typing my reply I stole it already... (or better I drew it down, since I'm using KiCad) :icon_wink:
Has the output buffer been finalized for this?
Is there a PCB layout with the buffer change?
Looking forward to this one ;D
Had a "mini bife chorizo" in BA today!!!
here is the pcb "NOT VERIFIED YET"
http://www.mediafire.com/?39my8ukybhelech
Note: red trace under tl074 is a wire
pappoo, have you a soundclip?.....thanks for sharing!. :icon_cool: