Parasite Phaser

12/23/2014

Update 2014-12-23: Savvas @ the tagboardeffects forum was kind enough to share a verfied vero layout for this one. :) Thanks alot! Original thread here. I added the vero layout to the bottom of the post.

Here is a new original design that I have been working on for some time. It's a Pulse Width Controlled phaser that uses a CMOS switch as variable resistors. The main advantage to this approach is that you don't need to match JFET transistors or LDR/Vactrols. I hope you like it! :)

Read about my progress, build reports, possible mods ect:
http://www.diystompboxes.com/smfforum/index.php?topic=108823.0

parasite_phaser_rev1_pcb.pdf
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parasite_phaser_vero.png
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parasite-phaser-schem.pdf
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20 Comments

John

12/2/2014 11:02:54 pm

Please, please post a vero layout for the Parasite Phaser. Thank you so much for your site.

Fredrik Lyxzén link

12/25/2014 01:33:06 am

Hi John
Now a vero layout it added. :) It's supposed to be verified, but I haven't built it myself yet. Cheers / Fredrik

clockman

8/10/2015 01:58:52 am

just finished the vero layout. Verified. works very well, has a small drop in overall volume compared to bypass signal. Great design, thank you so much for offering your work to the public.

george_drakakis link

9/21/2015 10:08:01 am

hi Fredrik,
this is an exceptional phaser!
i built the veroboard layout posted @ tagboardeffects.
if i had to re-built i would omit the 3dtp switch and add an external pot instead of a trimmer.
i have two questions though:
how can i modify the rate pot? only the lowest rates (up to 1/4 turn) are usable to my taste.
is there an optimum setting for the trim pot? after a certain point the phaser behaves like a pseudo-wah which is something i really like.
kind regards,
george

Fredrik Lyxzén link

9/22/2015 11:59:49 pm

Hi George,
I'm glad you like it. Thanks for the build report. :)

I agree with your ideas. I'm actually working on a updated version for the fabbed PCB that omits the SPDT switch and lowers the overall rate of the LFO.

To lower the rate of the LFO, increase the 330K resistor. It can be 470K or 680K for even slower speeds.

Regarding the trimpot. I like to set it exactly where the thumping sound goes away, so that the range is as wide as possible without any ticking. But there's no general rule, just trim by ear and taste. :)

cheers / Fredrik

george_drakakis link

9/23/2015 01:21:36 am

Hi Fredrik,
thanks for the tip about the LFO rate.
i guess i'll have to solder another resistor in series.
i think i got rid of the ticking (only for one position of the SPDT switch)
when i carefully placed the metal pots on the enclosure. i think i had a ground issue but i am not sure, i'll have to check again.
at the moment the trim is set as you suggested.
just for the record, the wah-like sound at higher trim settings is awesome, and Savvas @ tagboards did a great job with the veroboard.
once again thank you for this-always-on-phaser.
parasites never sounded better.
kind regards,
george

John

9/23/2015 05:59:53 pm

Is the double link (blue circle) at the very bottom supposed to be connected to another link, or is that a mistake. Thanks

John

9/24/2015 12:03:48 pm

Disregard my previous post. I just built it and it sounds fantastic. No volume drop on mine. I used 470k in place of 330k for slower speeds.

Fredrik Lyxzén link

9/24/2015 03:42:52 pm

Sorry that I did not reply earlier.. busy day. :) I'm glad to hear that you like it. :) cheers! / Fredrik

equis link

1/25/2016 08:38:44 am

Hi ! I built the pedal but I had some problems. the rate is too fast .and it has pop sounds every time at the same rate speed

Fredrik Lyxzén link

1/26/2016 10:29:24 am

Hi Equis,
It's hard to help without knowing more about your build.

The ticking you hear is a common problem, especially on vero layout. It helps to keep the wiring as short as possible and use a low current IC for the LFO section (IC5), either a TL022, TL062 or LM358. It can also help to increase DC filtering. Try a 220uF cap between +V and ground.

The speed issue is probably a wrong value component somewhere. Did you try a 470K resistor insted of the 330K as suggested here? You can increase it to 680K for slower speeds.

I hope that helps
Cheers / Fredrik

Equis

1/30/2016 08:35:13 am

Thanks for the reply!!! It is really annoying the ticking. I built it in a PCB .

equis

1/30/2016 09:13:27 am

i couldn't solve the problem yet. It is a really good sound pedal , Im going crazy!

Fredrik Lyxzén link

1/30/2016 03:21:47 pm

Hi Equis,
Have you tried adjusting the trimmer until the ticking goes away? It's could be a bias issue. That's all I can think of.

Aisha

10/2/2016 04:57:53 pm

I have built the etched PCB version. Great-sounding phase! The ticking is very hard to get rid of. I had best results with a TL022 for IC5. I originally had a TL062 in there but the ticking was madness. The rate seemed slower with the TL022. I tried 330k, 470k and 680k resistors with both op amps. The variation seemed more extreme with the TL062. I like the rates I can get with the TL062 but with that extreme ticking, I ended up sticking with the TL022.

Steven

2/11/2016 05:37:51 pm

Any chance we can get a full version of the artwork on the pedal?

Fredrik Lyxzén link

3/9/2016 03:25:45 am

Hi Steven,
Sorry about the late reply. I didn't see your post until now. The artwork were lost in a computer crash about one year ago unfortunatley. Otherwise I would gladely have shared it.

timothy

3/9/2016 05:34:01 pm

I built the corrupter v1.1 and the fuzz section works and sounds really good but there is no ring modulator sound. the frequency control does not work. I used a CD7040BE instead of a CD7040 could that be the issue???

Fredrik Lyxzén link

3/14/2016 06:21:51 am

Hi Timothy,
I guess you mean the CD4070. Any version of that chip should work. Sound like the oscillator in your build isn't working. Did you build it on vero of PCB? For me easier being able to help you, please post your issue here: http://www.madbeanpedals.com/forum/index.php?topic=21733.0
cheers, Fredrik

Bia link

9/11/2016 11:35:40 pm

Thanks for another wonderful post. Where else could anybody get that type of info in such an ideal way of writing?

Parasite Phaser

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