ASM-2

Uncle Krunkus · Posted: Fri Sep 22, 2006 2:04 pm Post subject:

No, the main thing is that it's stable. Being out by a little bit wouldn't matter, as long as you callibrate to that, it shouldn't change.

Uncle Krunkus · Posted: Mon Oct 16, 2006 5:37 am Post subject:

Okay, so I've started wiring up. I've never been so excited about the prospect of listening to a sine wave! Very Happy

I came up with the idea of doing multiple shielded signal runs using USB cable. I found about 8*2m ones in my junk box which I got given when I was at Jaycar. They are literally 4 conductors inside a really good foil and braid shield. Does anyone know any reason why I shouldn't use them? The main thing I wanted them for was to bring my Sqr/Tri/Saw/Sine outputs up to the selector switches, but do I need to worry about crosstalk? I can't imagine I do with signal levels like that, but what do you dudes think?

deknow · Posted: Mon Oct 16, 2006 4:09 pm Post subject:

uncle k,

if it's really differant wavforms from the same oscillator, i really doubt a little crosstalk would even be noticeable...after all, wouldn't they all be in phase all of the time?

deknow

Uncle Krunkus · Posted: Tue Oct 17, 2006 5:54 am Post subject:

Yeah, I realised today that I told someone else (zipzap?) here that they only needed to worry about shielding the noise cables. So I've kind of answered my own question really.

Uncle Krunkus · Posted: Sun Oct 22, 2006 7:22 am Post subject:

Here are the latest pics.

ASM2-j.jpg

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Here's the case finished. It turned out solid as the proverbial brick shithouse!

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ASM2-k.jpg

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Front panel, half dressed.

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ASM2-l.jpg

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What's inside, with the oscillators half wired up.

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dnny · Posted: Sun Oct 22, 2006 8:36 am Post subject:

looking good.
banana

toybox · Posted: Sun Oct 22, 2006 1:56 pm Post subject:

looks like it's going to be super nice!!!

sneakthief · Joined: Jul 24, 2006 Posts: 569 Location: Berlin

fantastic! i can't wait to see how you wire it up Smile

Joel · Joined: Sep 12, 2006 Posts: 97 Location: London, UK

awesome work, can't wait for the sound samples Shocked

do you have a big pointy wizard hat to wear while you play it?

Uncle Krunkus · Posted: Mon Oct 23, 2006 4:37 am Post subject:

Hey Sneakthief,
I've just finished wiring the VCOs, and I've realised that I need to do some fine tuning of the +/-10V reference. R1 & R4 were originally s'posed to be 267R and 287R (not sure why) now the updated schem shows them as 270R. I'll change them to be matched 1%, and the 1K5s, for which I used 5% carbon, I'll be changing to 1% as well. Laurie says on that schem to adjust the 1K2s for perfect +/-10V so I'm going to put in 200R 25 turn trimmers in series with 1K1s 1%. Aside from that everything seems to be working fine.

Uncle Krunkus · Posted: Mon Oct 23, 2006 4:45 am Post subject:

Of course not! People who build the "Wizard" wear wizard hats!
http://www.elby-designs.com/asm2-wizard/asm2-wizard-about.htm
I have a very impressive Sorcerer's hat to wear.

Joel · Joined: Sep 12, 2006 Posts: 97 Location: London, UK

Ah, my mistake Embarassed

(off to build the ASM2-Dunce.....)

sneakthief · Joined: Jul 24, 2006 Posts: 569 Location: Berlin

still haven't calibrated my +/-10v reference yet... i swear i'll get around to it!

ps. i heard the ASM-2 Dunce hat is easy to make Wink

questionable · Posted: Sat Oct 28, 2006 10:15 am Post subject:

any bleeps and/or bloops out of that thing yet?

Uncle Krunkus · Posted: Sat Oct 28, 2006 2:33 pm Post subject:

Yep,
I've got the oscillators running. I need to work out a problem with the V/Oct tracking, then I'll move onto the VCFs. I'll post some samples as soon as there's something decent happening.

sneakthief · Joined: Jul 24, 2006 Posts: 569 Location: Berlin

re. v/oct tracking - Laurie's instructions didn't work at all for me. Since both of my vco's have the same issue, I think there's something fishy but I haven't quite figured it out yet.

Let me know what kind of calibration issues you're dealing with. I want to get to the bottom of this too.

Uncle Krunkus · Posted: Sat Oct 28, 2006 3:59 pm Post subject:

sneakthief · Joined: Jul 24, 2006 Posts: 569 Location: Berlin

I've got 2 tl084's per vco. My problem is that when I use 5v on the cv-input (with nothing else connected), I can get the proper frequency, but the tracking is wonky.

That said, I can still get several octaves of decent tracking, just not as many as was claimed. As I said before, I think this might be related to my +/-10v reference not being calibrated yet.

cheers,
michel

Uncle Krunkus · Posted: Sun Oct 29, 2006 2:44 am Post subject:

I checked the datasheets for the LF347 and the TL084 today, and the large signal gain for the 347 is 100 V/mV whereas the 084 is 200 V/mV. I'm pretty sure that's my problem sorted out right there, but I'll see what Laurie reckons.

sneakthief · Joined: Jul 24, 2006 Posts: 569 Location: Berlin

just got a message from Laurie: seems that TL074's may be the way to go for the exponential converter (instead of a tl084). i'll try this it and report back how it works.

sneakthief · Joined: Jul 24, 2006 Posts: 569 Location: Berlin

I changed over the exponential converter opamp to a tl074 and I now get good tracking over 5 octaves. Great!

Uncle Krunkus · Posted: Mon Oct 30, 2006 5:00 am Post subject:

Cool, I'm glad your problems sorted. Rolling Eyes

sneakthief · Joined: Jul 24, 2006 Posts: 569 Location: Berlin

Uncle Krunkus · Posted: Sat Nov 11, 2006 6:18 am Post subject:

Both VCOs and VCF1 wired up and running really well.
It turns out that I had some old component values and a couple more things to sort out with this "prototype" board I got. I've tracked it all down and sorted it out. I definately feel like I'm learning more and more as things progress.
I've got to get some modulation sources happening! Very Happy