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Tim Servo
Joined: Jul 16, 2006 Posts: 924 Location: Silicon Valley
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tony void
Joined: Apr 26, 2011 Posts: 40 Location: Parma, Ohio
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Posted: Thu Aug 11, 2011 6:34 am Post subject:
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This looks like a fun build. 1 quad chip for all. Could this produce sub-audidle freqs. to use as a vc source? Those shapes just look like they could weird-out a vco,vcf, or vclfo. Etc.etc.etc. |
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emdot_ambient
Joined: Nov 22, 2009 Posts: 667 Location: Frederick, MD
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Posted: Thu Aug 11, 2011 10:16 am Post subject:
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Interesting...yeah, it would be nice to hear it used to modulate an oscillator and/or filter. _________________ Looking for a certain ratio since 1978 |
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bubzy
Joined: Oct 27, 2010 Posts: 594 Location: United Kingdom
Audio files: 64
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Posted: Thu Aug 11, 2011 3:18 pm Post subject:
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hey thats nice looking. will draw up a toner etch pcb for it and post soonish. currently have dual 8k lfo and waveshapers in my modular (the old version) |
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Tim Servo
Joined: Jul 16, 2006 Posts: 924 Location: Silicon Valley
Audio files: 11
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Posted: Thu Aug 11, 2011 5:04 pm Post subject:
The LFX experimental LFO (8K LFO and Weird Waveshapers) |
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tony void wrote: | This looks like a fun build. 1 quad chip for all. Could this produce sub-audidle freqs. to use as a vc source? Those shapes just look like they could weird-out a vco,vcf, or vclfo. Etc.etc.etc. |
Hi Tony,
Actually, the capacitor value shown will produce low frequency waves for use as a VC source. I used a different cap in the YouTube video so that it would be easier to see the various waveforms (hard to display sub audio waveforms without a lot of flickering), and also because I was curious as to what the waves would sound like. Still, this is meant primarily as an LFO (hence the subject of the thread). The cap shown in the schematic will give you a range of roughly 0.0125Hz (about 80 seconds) to 100Hz. I'll do a sound sample of the LFX modulating a VCO so you can hear how it works as a mod source. Another thing I like about this design is that it still has the triangle and square outputs if you want a more 'normal' LFO.
Tim (less 'normal') Servo |
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Tim Servo
Joined: Jul 16, 2006 Posts: 924 Location: Silicon Valley
Audio files: 11
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marvkaye
Joined: Mar 14, 2011 Posts: 225 Location: Fla
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Posted: Mon Aug 15, 2011 1:34 pm Post subject:
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Just curious, Tim... which opamp did you use for this guy?
<marv> |
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Tim Servo
Joined: Jul 16, 2006 Posts: 924 Location: Silicon Valley
Audio files: 11
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Posted: Mon Aug 15, 2011 1:46 pm Post subject:
The LFX experimental LFO (8K LFO and Weird Waveshapers) |
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Hi Marv,
Just a pair of plain old TL072s, although a TL074 would work just fine. I like the dual package because it makes routing things a little easier, and you can separate circuit blocks that might otherwise interfere with each other if they were all on the same chip (although this is a pretty rare problem, especially in an LFO).
Cheers,
Tim (plain old) Servo |
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marvkaye
Joined: Mar 14, 2011 Posts: 225 Location: Fla
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Posted: Tue Aug 16, 2011 9:17 am Post subject:
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Hey Tim,
Thanks for the heads up on the opamps.... I laid out a stripboard for this last night, haven't gotten through the verification so don't want to post it just yet. I used the 2- TL072's as per your suggestion, came out pretty tiny, about 1.3x3 including room for mounting. I'm anxious to see how it works... thanks again for sharing.
<marv> |
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bubzy
Joined: Oct 27, 2010 Posts: 594 Location: United Kingdom
Audio files: 64
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marvkaye
Joined: Mar 14, 2011 Posts: 225 Location: Fla
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Posted: Tue Aug 16, 2011 4:15 pm Post subject:
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Hi bubzy... thanks for posting that PCB layout... very cool indeed. (I need to learn how to do that... ) I have one simple question, though.... are the trace layers reversed?? The ExpressPCB specs say that red traces are the top layer and green ones are the bottom. I'm sure that swapping them is no big deal, I just want to make sure I'm not missing something that should be obvious. I also found that with a little judicious tweaking I can fit two of your layouts on one of their Mini-board blanks, makes them very reasonably priced....
Your thoughts??
<marv> |
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bubzy
Joined: Oct 27, 2010 Posts: 594 Location: United Kingdom
Audio files: 64
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Posted: Tue Aug 16, 2011 4:37 pm Post subject:
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i have actually put the green traces in as jumpers. but yeah you're probably right about the layers being the wrong way around. id wait until someone (or me) has actually built one of these before spending money though.. there can always be problems that aren't obvious until you build something ill probably get on it this week. |
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marvkaye
Joined: Mar 14, 2011 Posts: 225 Location: Fla
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Posted: Tue Aug 16, 2011 5:45 pm Post subject:
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Good idea... I'll await a progress report before going further. BTW, swapping the traces was a snap. Nice piece of software.
<M> |
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marvkaye
Joined: Mar 14, 2011 Posts: 225 Location: Fla
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Posted: Mon Aug 22, 2011 4:45 am Post subject:
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Hey bubzy, just curious if you had a chance to do anything with this PCB?? I started work on my stripboard for it but got distracted with other chores... I'd really prefer the PCB version, though, so my motivation to complete the stripboard was probably reduced considerably. I'm really looking forward to your update.
<marv> |
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tokyomatik
Joined: Jan 20, 2011 Posts: 171 Location: berlin
Audio files: 6
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Posted: Mon Aug 22, 2011 5:38 am Post subject:
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the videos are really interesting, and i woud like to give it a try, unluckily i can't open the pcb file with Eagle, any chances to have a version in pdf? |
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marvkaye
Joined: Mar 14, 2011 Posts: 225 Location: Fla
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Posted: Mon Aug 22, 2011 7:03 am Post subject:
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Quote: | unluckily i can't open the pcb file with Eagle |
Do yourself a favor and go to ExpressPCB http://www.expresspcb.com/ and download their free software. It's pretty popular for PCB layouts and lets you access their files directly and be able to modify them yourself as well... much more convenient than fooling with a PDF. Just a suggestion... |
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tokyomatik
Joined: Jan 20, 2011 Posts: 171 Location: berlin
Audio files: 6
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Posted: Mon Aug 22, 2011 4:15 pm Post subject:
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i already went to that web site but i use a mac, i didn't found a version for osx |
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bubzy
Joined: Oct 27, 2010 Posts: 594 Location: United Kingdom
Audio files: 64
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marvkaye
Joined: Mar 14, 2011 Posts: 225 Location: Fla
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marvkaye
Joined: Mar 14, 2011 Posts: 225 Location: Fla
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tokyomatik
Joined: Jan 20, 2011 Posts: 171 Location: berlin
Audio files: 6
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Posted: Mon Aug 22, 2011 8:24 pm Post subject:
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i'm trying to open the file but it's not pdf or is damaged |
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bubzy
Joined: Oct 27, 2010 Posts: 594 Location: United Kingdom
Audio files: 64
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Posted: Mon Aug 22, 2011 11:15 pm Post subject:
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marvkaye : nice work. how the heck did i miss that (considering that i follow the schematic with a highlighter pen....... :S)? original now changed. please post the expresspcb files up, dual board is a nice idea too.
new pdfs uploaded (instead of the wrong zip file last time. sorry) |
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marvkaye
Joined: Mar 14, 2011 Posts: 225 Location: Fla
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Posted: Tue Aug 23, 2011 4:48 am Post subject:
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Glad you liked it. Here are the ExpressPCB file and PDFs.
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LFXx2_PCB_bot.pdf |
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10.35 KB |
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623 Time(s) |
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LFXx2_PCB_top.pdf |
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9.62 KB |
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874 Time(s) |
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LFXx2_PCB_screen.pdf |
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12.49 KB |
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645 Time(s) |
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marvkaye
Joined: Mar 14, 2011 Posts: 225 Location: Fla
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Tim Servo
Joined: Jul 16, 2006 Posts: 924 Location: Silicon Valley
Audio files: 11
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Posted: Fri Aug 26, 2011 4:01 pm Post subject:
The LFX experimental LFO (8K LFO and Weird Waveshapers) |
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Wow, looks good. I haven't checked the layout carefully, but at first glance it looks like everything is there. About the only thing I might recommend is adding a name and date. You can even put it in the bottom layer copper. Something as simple as "LFX - 2011-08" might save you some time and head scratching if you etch a board and then don't get to actually putting parts on it for a few months. I like adding the date so that I have a rough idea what schematic I used - in case an update gets posted later.
One more thought: I'd probably add a transistor and a few resistors for an LED rate monitor. I have some designs I was going to post, so you might want to hold off for just a bit if you want to add this to your layout (otherwise, the transistor buffer is so simple, it would be easy to add it with a small piece of perf board).
In any case, hope everyone has fun with the LFX.
Tim (LFX Rated) Servo |
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