Author Topic: Understanding the EHX Y-Triggered Filter  (Read 20635 times)

Scruffie

Re: Understanding the EHX Y-Triggered Filter
« Reply #40 on: November 14, 2019, 03:53:56 PM »
That's quite a nice filter there. Thanks for the vid Mark.
I noticed the envelope detector didn't trigger every time.
When you play it, it kinda keeps triggering and triggering and then just jams up, before starting again, you have to adapt your playing a lot and even then it's not particularly consistent.

Having said that, Mark isn't wrong, studying it more might lead to it being developed in to something more useful and yeah the filter itself is quite pleasant, it's the same type as found in the mini (not micro) synth.

Mark Hammer

Re: Understanding the EHX Y-Triggered Filter
« Reply #41 on: November 14, 2019, 04:06:09 PM »
Yep. Not your basic Doctor Q variant.

Kipper4

Re: Understanding the EHX Y-Triggered Filter
« Reply #42 on: November 14, 2019, 04:39:42 PM »
I might have to reread that a few times, but yer 4046 pll right.
"Duck_Arse
otherwise, you might end-up with SOIC or gullwings, for surface mounts."


Smoke me a Kipper. I'll be back for breakfast.

Grey Paper.
http://www.aronnelson.com/DIYFiles/up/

rankot

Re: Understanding the EHX Y-Triggered Filter
« Reply #43 on: November 14, 2019, 05:30:41 PM »
This is ltspice model of a filter, hopefully w/o errors. Fixed so it can use LM13700 OTA, simulation works fine.

Code: [Select]
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« Last Edit: November 15, 2019, 03:26:37 PM by rankot »
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rankot

Re: Understanding the EHX Y-Triggered Filter
« Reply #44 on: November 15, 2019, 03:28:10 PM »
This is the final corrected schematic. There are still some parts (marked with ?) for which I'm not sure if they are really necessary, but this one works fine, at least in ltspice.



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Mark Hammer

Re: Understanding the EHX Y-Triggered Filter
« Reply #45 on: November 15, 2019, 04:10:28 PM »
As much as I appreciate it, and the work involved, I am confused by your drawing.  Are you subbing a 13700/13600 for the original 3094/1048?

Scruffie

Re: Understanding the EHX Y-Triggered Filter
« Reply #46 on: November 15, 2019, 07:54:35 PM »
As much as I appreciate it, and the work involved, I am confused by your drawing.  Are you subbing a 13700/13600 for the original 3094/1048?
He is, the current source/sink darlington from the 3094 is in the bottom right corner of the schematic with the "P1, P8" connections.

rankot

Re: Understanding the EHX Y-Triggered Filter
« Reply #47 on: November 16, 2019, 05:12:59 AM »
As much as I appreciate it, and the work involved, I am confused by your drawing.  Are you subbing a 13700/13600 for the original 3094/1048?

Yes Mark, since I can't find CA3094, I decided to recreate this using LM13700. Also, I confirm that R21 and R37 on my schematic are not necessary - they're present in the "official" schematic, but not on the PCB photos you've shared. But I'm still not sure about C23 (10u), it's not present in original schematic, but I believe I saw it on the PCB. It definitely affects operation.

I must ask Mark or anyone else having an original pedal, to check out R2, R4, R5, R6 value. They seem as 1k to me (if photograph colors are right), not as 10k as shown on original schematic.
« Last Edit: November 16, 2019, 01:12:12 PM by rankot »
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StephenGiles

Re: Understanding the EHX Y-Triggered Filter
« Reply #48 on: November 16, 2019, 08:16:01 AM »
I echo Mark's appreciation, but I'll have to restate the 13700 rectangle with usual triangles to get my head around this!!
"I want my meat burned, like St Joan. Bring me pickles and vicious mustards to pierce the tongue like Cardigan's Lancers.".

rankot

Re: Understanding the EHX Y-Triggered Filter
« Reply #49 on: November 16, 2019, 01:40:59 PM »
OK, like this:



Just have in mind that this is the same as the previous schematic, just replaced LM13700 symbol. Also, previous schematic uses both halves of LM13700 in parallel.
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PRR

Re: Understanding the EHX Y-Triggered Filter
« Reply #50 on: November 16, 2019, 02:14:31 PM »
I have not digested plan in #49. But it appears if you use LM13700, then the two NPN between R42 and R43 can be done by the buffer inside the '13700, and IAC R42 should not be needed. Saves 3 parts.
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Scruffie

Re: Understanding the EHX Y-Triggered Filter
« Reply #51 on: November 16, 2019, 02:50:38 PM »
I have not digested plan in #49. But it appears if you use LM13700, then the two NPN between R42 and R43 can be done by the buffer inside the '13700, and IAC R42 should not be needed. Saves 3 parts.
There's no access to the collector on the 13700's internal darlington.

You can do it with just one transistor if you want and then ignore R42.

rankot

Re: Understanding the EHX Y-Triggered Filter
« Reply #52 on: November 16, 2019, 02:56:53 PM »
I have not digested plan in #49. But it appears if you use LM13700, then the two NPN between R42 and R43 can be done by the buffer inside the '13700, and IAC R42 should not be needed. Saves 3 parts.

I tried that in ltspice, but it doesn't work as expected.
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StephenGiles

Re: Understanding the EHX Y-Triggered Filter
« Reply #53 on: November 16, 2019, 04:56:34 PM »
OK, like this:



Just have in mind that this is the same as the previous schematic, just replaced LM13700 symbol. Also, previous schematic uses both halves of LM13700 in parallel.

Many thanks!
"I want my meat burned, like St Joan. Bring me pickles and vicious mustards to pierce the tongue like Cardigan's Lancers.".

rankot

Re: Understanding the EHX Y-Triggered Filter
« Reply #54 on: November 16, 2019, 05:32:30 PM »
I have not digested plan in #49. But it appears if you use LM13700, then the two NPN between R42 and R43 can be done by the buffer inside the '13700, and IAC R42 should not be needed. Saves 3 parts.
There's no access to the collector on the 13700's internal darlington.

You can do it with just one transistor if you want and then ignore R42.

Like this? This seems to work in ltspice.


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Scruffie

Re: Understanding the EHX Y-Triggered Filter
« Reply #55 on: November 16, 2019, 07:45:40 PM »
I have not digested plan in #49. But it appears if you use LM13700, then the two NPN between R42 and R43 can be done by the buffer inside the '13700, and IAC R42 should not be needed. Saves 3 parts.
There's no access to the collector on the 13700's internal darlington.

You can do it with just one transistor if you want and then ignore R42.

Like this? This seems to work in ltspice.


Yes, but I have had more consistent results with a discrete pair of transistors, but it will work like that.

rankot

Re: Understanding the EHX Y-Triggered Filter
« Reply #56 on: November 17, 2019, 05:13:37 AM »
In that case, I will stay with a few extra parts :)

Did anyone with an original pedal had time to check values of resistors mentioned above?
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rankot

Re: Understanding the EHX Y-Triggered Filter
« Reply #57 on: November 17, 2019, 08:54:49 AM »
I'm finally done with the PCB for this. I need some help - is this ground plane done well or not? I don't have ground loops, but I wander if it is OK regarding current flow. Please help!



Single layer, with two SMD capacitors (for PS filtering right under ICs).
« Last Edit: November 17, 2019, 08:56:53 AM by rankot »
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PRR

Re: Understanding the EHX Y-Triggered Filter
« Reply #58 on: November 18, 2019, 10:35:01 PM »
> There's no access to the collector on the 13700's internal darlington.

Duh. Sorry, brain fart.
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rankot

Re: Understanding the EHX Y-Triggered Filter
« Reply #59 on: November 19, 2019, 08:22:52 AM »
Both sides separated:


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