A simple PT2399 diy flanger pedal?

Stompboxes circuits published in magazines, books or on DIY electronics websites.
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~arph
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Post by ~arph »

Hides-His-Eyes wrote:you could try v_ref modulation like the little angel
I am trying this one of these days. I have some PT2396'es and yes, they are HUGE :shock: about twice the size of a pt2399.
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Post by Dr Tony Balls »

the PT2396 may be huge, but its not exactly like there are a lot of small Flanger circuits around. Hardly a big deal, imo.

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Post by ppluis0 »

Hi there,

There is an "Echo processor IC" pin to pin compatible with the PT2399 that is named HT8970 and is manufactured by Holtek.

The datasheet of this chip are fond here: http://pdf1.alldatasheet.com/datasheet- ... T8970.html

The only difference with the PT2399 is that this IC has only 20 kilobits of storage memory and the minimun delay time attainable is of 30 milliseconds.

Is this time little enough to use as a flanger ??

As consecuence of search the web, I discover that there exist the HT8972 that looks to be identical and pin to pin compatible with the 2399...

Cheers,
Jose

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Post by merlinb »

A while ago I designed a PT2399 flanger using two devices, along the same lines mentioned earlier in this thread.
To avoid latency the dry signal was also mixed with the output, which also gave it a hint of reverb (interesting but unwanted). It does through zero and has a +/- phase switch. I got as far as designing the PCB, but in the end I decided I'd lost interest in it and would probably never use a flanger anyway, but I here is the unadulterated schem in case anyone else is interested.

http://dl.dropbox.com/u/57831278/flanger.pdf

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Post by rocklander »

might have a crack at making a PCB for that.. thank you sir!
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Post by frequencycentral »

merlinb wrote:A while ago I designed a PT2399 flanger using two devices, along the same lines mentioned earlier in this thread.
To avoid latency the dry signal was also mixed with the output, which also gave it a hint of reverb (interesting but unwanted). It does through zero and has a +/- phase switch. I got as far as designing the PCB, but in the end I decided I'd lost interest in it and would probably never use a flanger anyway, but I here is the unadulterated schem in case anyone else is interested.

http://dl.dropbox.com/u/57831278/flanger.pdf
Wow! Holy grail Batman!

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Post by ~arph »

I want to hear it. 30ms still Seems too long
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Post by ppluis0 »

~arph wrote:I want to hear it. 30ms still Seems too long
It's funny: the datasheet of the PT2399 indicates that have 44 kbit of ram, and a minimum delay time of 31.3 msec with the time potentiometer practically sort circuited.

The HT8970, having 20 kbit of ram, has a minimum delay of 29.78 msec... :scratch:

I assume that the amount of storage ram is directly correlated to min and max delay times... or not ?

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Post by merlinb »

~arph wrote: 30ms still Seems too long
It is. That's why you have to use two of them...

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Post by hbo »

merlinb wrote:A while ago I designed a PT2399 flanger using two devices, along the same lines mentioned earlier in this thread.
To avoid latency the dry signal was also mixed with the output, which also gave it a hint of reverb (interesting but unwanted). It does through zero and has a +/- phase switch. I got as far as designing the PCB, but in the end I decided I'd lost interest in it and would probably never use a flanger anyway, but I here is the unadulterated schem in case anyone else is interested.

http://dl.dropbox.com/u/57831278/flanger.pdf
I was curious to know what this circuit would sound like so I built one on vero.

Image

I initially had problems with the LFO not working properly, but eventually found out that it wasn't getting enough voltage with the series 1N4001 on the power rail. Having sorted this it worked almost flawlessly, but I found there's a sort of vibrato pitch wobble thing happening towards one end of the sweep. This may of course be due to a mistake on my part, but I don't know enough theory to even know where to begin fixing this.

Anyway, thought I'd share my findings.

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Post by drbob1 »

Hides-His-Eyes wrote:I'd love to see an eagle library for one of those!

I wonder if you could make a flanger by modulating the length of a spring. :idea: :scratch:
You know, if you're going full mechanical, why not a pair of small tape recorders (say Goodwill dual cassette decks) and have an LFO vary the tape speed in an alternating manner? If you change the rate of both decks alternating you'll have true TZF. YOu just have to work out the ability to record/read simultaneously on a 2 head deck...

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Post by Dr Tony Balls »

Anyone other than Harald try this? Im curious about it.

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Post by wasweissich »

I tried it some time ago, and it worked.
I think i´ll try it once again.

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Post by OnTheTundra »

hbo wrote:
merlinb wrote:A while ago I designed a PT2399 flanger using two devices, along the same lines mentioned earlier in this thread.
To avoid latency the dry signal was also mixed with the output, which also gave it a hint of reverb (interesting but unwanted). It does through zero and has a +/- phase switch. I got as far as designing the PCB, but in the end I decided I'd lost interest in it and would probably never use a flanger anyway, but I here is the unadulterated schem in case anyone else is interested.

http://dl.dropbox.com/u/57831278/flanger.pdf
I was curious to know what this circuit would sound like so I built one on vero.

[ Image ]

I initially had problems with the LFO not working properly, but eventually found out that it wasn't getting enough voltage with the series 1N4001 on the power rail. Having sorted this it worked almost flawlessly, but I found there's a sort of vibrato pitch wobble thing happening towards one end of the sweep. This may of course be due to a mistake on my part, but I don't know enough theory to even know where to begin fixing this.

Anyway, thought I'd share my findings.
I built this and the sweep goes from non existent to very slow. What steps should I take to increase the speed of the lfo?

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Post by jhergonz »

anybody have a schematic for this?

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Post by Nocentelli »

jhergonz wrote: 04 Oct 2020, 11:57 anybody have a schematic for this?
Dual-PT2399-flanger.jpg
Steven_M wrote: 21 Jan 2011, 17:52
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Post by jhergonz »

Nocentelli wrote: 04 Oct 2020, 17:13
jhergonz wrote: 04 Oct 2020, 11:57 anybody have a schematic for this?
Dual-PT2399-flanger.jpg
thank you

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