EH Echoflanger  [schematic]

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...

Re: EH Echoflanger

Postby Govmnt_Lacky » 12 Mar 2012, 19:21

phibes wrote:To explain more on the layout, the red +15V traces are your VDD. They all need to be jumpered together as per the note says. The BBD's don't connect directly to the VDD. The LED is being used as the pedal indicator (it's always on once the pedals plugged in) and to bias the bbds. So the positive end of the LED goes to +15V, the negative end of the LED will be your VBB. If I remember right, the RED LED will cause a 1.5V-2V voltage drop. So that's where your VDD and VBB will be. Way to get major bang for buck out of parts!


I see that now. Thanks for the explanation.

I still do not understand why they chose to connect the Vdd to the LED. I would think they would have connected Vdd directly to 15V and then connect the Vbb to the LED (after the voltage drop)

This way, the SADs are performing at an optimal level.

In the end, I suppose there was a reason but I just do not grasp it. After looking at the MXR flanger, it appears they did the same thing (tying Vdd and Vbb together) BUT, they tied them both to the 15V input.
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Re: EH Echoflanger

Postby phibes » 13 Mar 2012, 05:55

I'm not surprised they did it like that. I'm sure they were just trying to keep it at a minimum. It really isn't hifi compared to other things that used the SAD1024 so I don't think the SAD1024 needs to be at configured to it's optimum level. I haven't used the chips enough to really make an honest opinion. Try it both ways and see if you hear a difference.
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Re: EH Echoflanger

Postby Govmnt_Lacky » 14 Mar 2012, 15:02

phibes wrote:I'm not surprised they did it like that. I'm sure they were just trying to keep it at a minimum. It really isn't hifi compared to other things that used the SAD1024 so I don't think the SAD1024 needs to be at configured to it's optimum level. I haven't used the chips enough to really make an honest opinion. Try it both ways and see if you hear a difference.


Seeing as trying it with seperate Vdd and Vbb would mean altering the circuit and changing the traces, I will just stick with the original plan 8) After the circuit is proven and working, then I will mess with seperate Vdd and Vbb. Don't want to jeopardize those SAD chips unnecessarily :shock:

Gonna try this unit with a transformer instead of the voltage multiplier. This way I don't have to worry about the currrent draw :thumbsup
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Re: EH Echoflanger

Postby phibes » 14 Mar 2012, 18:48

Yeah good plan.

What transformer ya gonna use?
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Re: EH Echoflanger

Postby Govmnt_Lacky » 14 Mar 2012, 20:18

phibes wrote:Yeah good plan.

What transformer ya gonna use?


Triad magnetics

F115X
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Re: EH Echoflanger

Postby phibes » 14 Mar 2012, 22:02

:thumbsup Good choice, I was gonna mention them. I didn't look at that particular one though, definitely a perfect pick.
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Re: EH Echoflanger

Postby Govmnt_Lacky » 14 Mar 2012, 23:50

phibes wrote::thumbsup Good choice, I was gonna mention them. I didn't look at that particular one though, definitely a perfect pick.


Can't take credit for that one. Another forum member led me to that one :secret:
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Re: EH Echoflanger

Postby Govmnt_Lacky » 26 Mar 2012, 13:29

I put together an excel spreadsheet for the Parts List for this project.

Message me if you are interested. :applause:
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Re: EH Echoflanger

Postby Govmnt_Lacky » 27 Mar 2012, 15:14

Ok...

So I got me a 5M Linear pot as described in the pdf doc.

Now, can someone PLEASE help me with how to set the tapering resistors to get this as close to a 2M Anti-log pot as possible? I have read the applicable articles at GEO and I still have no clue on what values to use and where to place them on the pot :oops:

I know that if I strap about 3M across lugs 1 and 3 that I would have around 2M but it would still be LINEAR.
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Re: EH Echoflanger

Postby nelson » 01 Apr 2012, 14:58

Hello,

I am Paul Nelson. I did the PDF project years and years ago. So, it's not fresh in my mind.

I do know of one person who has built and verified the Layout.

The layout comes from my site where there is contact info.

http://electroconducive.googlepages.com

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Re: EH Echoflanger

Postby Govmnt_Lacky » 01 Apr 2012, 19:33

nelson wrote:Hello,

I am Paul Nelson. I did the PDF project years and years ago. So, it's not fresh in my mind.

I do know of one person who has built and verified the Layout.

The layout comes from my site where there is contact info.

http://electroconducive.googlepages.com


Hey Paul!

Excellent project BTW... the moment I saw it I had to build it! :applause:

I do have some items that I have found during my build that I am going to share here just in case someone else decides to tackle this beast.

1) On the PCB transfer, there is a missing pad for the 2.4K resistor directly above the 4049 IC. It is shown in the layout but, it is missing from the transfer. Easily correctable by drilling a hole next to the appropriate trace and connecting to the adjacent cap.

2) There is a mis-marked capacitor on the layout. Between the 4558s you have a cap listed at 0.18uF and another listed at .018uF. According to the factory schematic, BOTH of these caps need to be .018uF

3) After looking over multiple pics of the original unit, it appears that one of the trimmers is an incorrect value. On all of the pics I have seen, the trimmer between the 4049 and the SAD chip is supposed to be 1K (not the 100K on the layout). This is also in the factory schematic.

Just got the PCB soldered up and have yet to install the ICs and fire it up (still waiting for a few parts) but I do know this... I AM NOT looking forward to trimming this circuit. At a whopping 7 trimmers :shock: it looks to be a daunting task!

I will report any progress and attempt to get some form of trimming tutorial up here when I am done.

P.S. If anyone with a bit more knowledge than I can look over the layout/schemo and help identify the trimmers, it would be appreciated :thumbsup
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Re: EH Echoflanger

Postby phibes » 01 Apr 2012, 20:10

From a glance, trimmers look TR1 & TR2 look like limiting resistors to minimize distortion, TR3 will control how much feedback you want the actual control to control, TR4 is a voltage divider for V2, TR5 is a voltage divider for V3, TR6 is your BBD balance, TR7 is probably bias to LM311, I didn't look into how the chip was being used.

Check out the datasheets. Shouldn't be too bad to set up though. Big props for taking this one on!

You might wanna redraw the schematics, the factory ones are a pain in the ass to read.
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Re: EH Echoflanger

Postby nelson » 01 Apr 2012, 20:15

Govmnt_Lacky wrote:
nelson wrote:Hello,

I am Paul Nelson. I did the PDF project years and years ago. So, it's not fresh in my mind.

I do know of one person who has built and verified the Layout.

The layout comes from my site where there is contact info.

http://electroconducive.googlepages.com


Hey Paul!

Excellent project BTW... the moment I saw it I had to build it! :applause:

I do have some items that I have found during my build that I am going to share here just in case someone else decides to tackle this beast.

1) On the PCB transfer, there is a missing pad for the 2.4K resistor directly above the 4049 IC. It is shown in the layout but, it is missing from the transfer. Easily correctable by drilling a hole next to the appropriate trace and connecting to the adjacent cap.

2) There is a mis-marked capacitor on the layout. Between the 4558s you have a cap listed at 0.18uF and another listed at .018uF. According to the factory schematic, BOTH of these caps need to be .018uF

3) After looking over multiple pics of the original unit, it appears that one of the trimmers is an incorrect value. On all of the pics I have seen, the trimmer between the 4049 and the SAD chip is supposed to be 1K (not the 100K on the layout). This is also in the factory schematic.

Just got the PCB soldered up and have yet to install the ICs and fire it up (still waiting for a few parts) but I do know this... I AM NOT looking forward to trimming this circuit. At a whopping 7 trimmers :shock: it looks to be a daunting task!

I will report any progress and attempt to get some form of trimming tutorial up here when I am done.

P.S. If anyone with a bit more knowledge than I can look over the layout/schemo and help identify the trimmers, it would be appreciated :thumbsup



Thank for the info. I do remember in the distant past when the layout was verified that there was an issue with the trimmer.

I would check out the trimmer biasing process for the EH Electric mistress. It's on my site in the schematics section. That should give you an idea of what;s involved here.

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Re: EH Echoflanger

Postby Govmnt_Lacky » 01 Apr 2012, 20:46

I appreciate the help Paul!

I will look into the procedures for the EM however, I think this one is going to be a bit more involved :hmmm:
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Re: EH Echoflanger

Postby phibes » 01 Apr 2012, 20:56

Nm, TR7 is for the clock.

You gonna calibrate it by ear or scope?
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Re: EH Echoflanger

Postby Govmnt_Lacky » 01 Apr 2012, 22:50

phibes wrote:Nm, TR7 is for the clock.

You gonna calibrate it by ear or scope?


I am lucky enough to have some good tools to perform calibrations. I have a regulated PS, signal generator, and a really good digital oscope. I do not have a distortion analyzer though.

I would like to use these to get it calibrated but, I will go by ear if need be. (although I do not have the best ears in the business :oops: )

Here is what I ASSume are the trimmer assignments:

TR1: ??
TR2: ??
TR3: Feedback trim
TR4: BBD bias (Distortion) for IC3
TR5: BBD bias (Distortion) for IC4
TR6: BBD Level trim
TR7: Clock

Any ideas?
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Re: EH Echoflanger

Postby nelson » 02 Apr 2012, 00:37

TR1 + 2 are just signal level adjustments for the compander and SAD1024.

The rest you have right.

Analogkid on here has built this from my project file. He might have some tips.

Good luck!
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Re: EH Echoflanger

Postby theehman » 02 Apr 2012, 13:44

For those of you playing at home, here's the original EH calibration instructions for the Echoflanger/Polypchorus/Polyflange:

EchoflangerCal.pdf
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Re: EH Echoflanger

Postby Govmnt_Lacky » 02 Apr 2012, 14:04

Ron,

You are truely a gentleman and a scholar!!! :applause:

...and please ignore my copious amount of PMs regarding this :oops:

Your help is greatly appreciated!! :horsey:

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Re: EH Echoflanger

Postby nelson » 02 Apr 2012, 15:39

Thanks Ron! Mind if I put that document on my site?

I've had it in mind to update this project for some time.

It was actually the pedal that gave me the impetus to pick up this hobby.

Since I'm returning to the hobby after a long hiatus.

It seems somehow poetic to make this one a priority to work on.

I no longer have the original working documents. So, it would be a bit of work.

I'm currently thinking about doing a project version with the MN3007. Since the SAD1024 is rarer than a virgin birth.

First thing that comes to mind in a conversion is the second SAD1024 is ran in parallel making it a 512 stage bbd. So, I'd need to double the clock speed then divide it to feed the other delay line in a MN3007 version. Since it is strictly a 1024 stage BBD. Even then, I wonder if the magic is somewhat due to the parallel 512 stage. So, it might be worth it to use a third MN3007 just to recreate it.

This thread and your build should be enough to make any errors/corrections clear to create a definitive (readable) Schematic. Which would be step one.

Any errors or things you pick up on. Please do post them here Govmnt_lacky!

I'll see if I can get Analogkid to chime in with what he remembers.

Thanks for taking this bad boy on!
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