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 Forum index » DIY Hardware and Software » Thomas Henry designs
Completed Thomas Henry LFX 8K LFO..Highest frequency 41Hz...
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mubase



Joined: Mar 24, 2011
Posts: 110
Location: London UK
Audio files: 5

PostPosted: Fri Mar 15, 2013 6:56 am    Post subject: Completed Thomas Henry LFX 8K LFO..Highest frequency 41Hz... Reply with quote  Mark this post and the followings unread

Hi to everyone on this most wonderful site .
Happy to say I have succesfully press n peeled and assembled a Thomas Henry LFO using the templates from the LFX page:
http://www.electro-music.com/forum/topic-49081.html&postorder=asc
and thanks to Buzby for the design! (and if it was you, thanks for selling me the 2K tempcos on ebay the other day .Smile )
I've included a picture.


I have a couple of questions...
The first time I tested it I got no output. This was due to a faulty TL084 so I swapped it for an LF444. I don't have a TL084 at the moment. Would anyone know if this would affect its performance in any way? I get beautiful triangles, squares and the WAVE output gives me everything in between those two...
The highest frequency I can get from it according the the scope is 5x5mS=25mS=40Hz...
Can it go higher?
I am using a 5.1Mohm instead of a 5.0 Mohm on R1 and a 270K instead of a 280K on R20...Will this affect it much? I wouldn't have thought so...


LFX_LFO_Finished.jpg
 Description:
LFX LFO finished. Press n peel blue, iron, Ferric chloride (sponge dab method, saves Ferric)
 Filesize:  750.72 KB
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LFX_LFO_Finished.jpg



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elmegil



Joined: Mar 20, 2012
Posts: 1484
Location: Chicago
Audio files: 14

PostPosted: Fri Mar 15, 2013 7:46 am    Post subject: Reply with quote  Mark this post and the followings unread

I'm pretty sure that's Tim Servo's not Thomas', since it only has Magic Smoke listed in the copyrights. Smile

I haven't built this guy so I can't speak to expected frequency, but I'd be triple checking C1 to be sure it was .01uF since that seems like it would be key to frequency. Did you use a high quality cap there? Does it possibly have poor tolerance?

Just ideas, as I say Smile
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mubase



Joined: Mar 24, 2011
Posts: 110
Location: London UK
Audio files: 5

PostPosted: Fri Mar 15, 2013 8:07 am    Post subject: RE: Reply with quote  Mark this post and the followings unread

Hi!
Thanks, you're right. Its a Tim Servo special.
The cap is a standard metallized polyester 10nF. The components are pretty much standard all the way (I could've put a ceramic 103 cap in but Metallised polyester seem better..)
I've found a Tl084 I didn't know I had and swapped the chips. They both show the same performance..
I've done scope tests but in a few minutes Im going to rig it up to my SN voice and see how she sounds... Smile

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Tim Servo



Joined: Jul 16, 2006
Posts: 924
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PostPosted: Thu Mar 28, 2013 10:19 pm    Post subject: Completed Thomas Henry LFX 8K LFO..Highest frequency 41Hz... Reply with quote  Mark this post and the followings unread

Hey Mu,

Actually, R1 affects the triangle wave offset and R20 limits the base current to the transistor that does switching for the sign changer (Wave A). Luckily, neither of those parts should affect the frequency. I'd double check the timing cap, and R3, R4, R5 and R6. R3, 4, 5 will have a direct effect on the frequency, and R6 will have some effect on the overall range too.

Hope this helps!

Tim (father of the LFX... I'm told he doesn't look anything like me) Servo
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bubzy



Joined: Oct 27, 2010
Posts: 554
Location: United Kingdom
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PostPosted: Sat Mar 30, 2013 2:37 pm    Post subject: Reply with quote  Mark this post and the followings unread

heh, you're welcome for the pcb, and yes it was me Smile thanks for your custom !!
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