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[BACK AGAIN] Eurorack: Haible Living VCOs by R*S
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page Previous  1, 2, 3, 4 ... 13, 14, 15  Next [all]
Author [BACK AGAIN] Eurorack: Haible Living VCOs by R*S
spotta
More questions!
I choose the THAT300 option over the BCM847DS for no other reason than THAT chips seem to have a good reputation. Neither have been fitted yet, so I'm still free to choose, can anyone tell me what differences I can expect between the two choices? I'm guessing there must be a difference otherwise why the choice.
Also the BC550/560 - Should these be matched?
AlanP
Got a few THAT300's on the way as well, and what orientation are they? The silkscreen is not clear on this...
spotta
I think pin 1 has a little mark on the inside of the pad - it almost looks like a mark on the tempco silkscreen marking. hopefully Ralf can confirm.
Altitude909
So is this the build thread? I have my Mouser BOM that I can share..
shabax
Altitude909 wrote:
So is this the build thread? I have my Mouser BOM that I can share..

Sounds like it is.
Please do share.
Hazium
Altitude909 wrote:
So is this the build thread? I have my Mouser BOM that I can share..



I'm into taking a look at that. What did it end up costing?
Altitude909
$166 with no pots, jacks, and DIL power header. Everything else for the voice board and euro control surface are there.

http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=bd822 dece0
didahdrieghe
Altitude909 wrote:
$166 with no pots, jacks, and DIL power header. Everything else for the voice board and euro control surface are there.

http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=bd822 dece0


You rock Altitude909! Have you built yours?
Altitude909
^waiting for parts

It's a pretty straightforward BOM, I opted for the super-matched pairs and nicer opamps where it made sense. Dont forget pots, I use the smallbear alphas so they are not included
nordlead
Hey,

just found the notifications of the last 12 posts or so in my Spam-folder! Sorry about not having seen this.

Picked up another batch of main pcbs today - including 3 boards with MAT14 w00t - probably overkill, but the specs of the MAT14 are so impressive, thought this is worth a try ...



Why use super-matched transistors? There should be some improvement in tracking (due to better log conformity) and possibly temperature drift (due to better matching) - whether you notice either in real life is hard to say, also whether it's worth the added $$$ ... might not make any sense at all, still I know I need to build me a MAT14 version!
Altitude909
Working on mine now. First BOM Error, TEMPCO, says quantity is 1, it is 3
Altitude909
Question: On the control surface PCB, Should I populate just the headers that have a foot print? The long one has 35 holes but the footprint is 33 holes and the two extra are connected to the 12 pin one to its left. I assumed this was since a 35 pin header as easier to find than a 33 pin but that's not really the case since no one has odd numbered ones that long anyway (My bom has a 36 pin)
nordlead
Altitude909 wrote:
Question: On the control surface PCB, Should I populate just the headers that have a foot print? The long one has 35 holes but the footprint is 33 holes and the two extra are connected to the 12 pin one to its left. I assumed this was since a 35 pin header as easier to find than a 33 pin but that's not really the case since no one has odd numbered ones that long anyway (My bom has a 36 pin)


Yes and no - I generally use those precision sockets (headers) that can be cut to length, so the 35 pins is not related to part choices.

Those 2 extra pins you noticed are not required, but an option (that's probably not relevant to most builders) - these two pins bring out the 4th (unused) input of the mixer in the driver section, in case someone wanted to experiment / hardwire another signal into that mixer. The outmost (lowest) pad is the actual prolonged input (it's a GND-pad next to it).

To connect the panel pcb to the main pcb, only the pads that exist on both pcbs should (can) be used - I recommend actually stacking the boards together with the pin strips and connectors without soldering first and check if everything is correct / correctly aligned. Also if you use precision sockets, it will be very hard to disconnect the boards again (it is possible, but go very slowly, mm by mm), so (finally) glueing the boards together is done at the very end - e.g. solder those connectors only onto one of the pcbs and leave the other side unsoldered till the end.

Hope this helps!
Altitude909
Thanks.

One other thing: Are all the SMD bypass pads supposed to be populated? There are two on the back of my board that dont have parts on them (coming off the power header to the VCOs)
nordlead
Altitude909 wrote:
Thanks.

One other thing: Are all the SMD bypass pads supposed to be populated? There are two on the back of my board that dont have parts on them (coming off the power header to the VCOs)


No need to worry about the SMD pads (those pads you mention aren't for bypass caps, but an alternative footprint for SMT beads. I suggest to go with normal (TH) beads).
Altitude909
sorry, I wasnt clear. I ordered the board WITH the BCM matched pairs and the 1206 bypass parts soldered. Everything on the back has parts already except those two..
nordlead
Altitude909 wrote:
sorry, I wasnt clear. I ordered the board WITH the BCM matched pairs and the 1206 bypass parts soldered. Everything on the back has parts already except those two..


(?!) No, that's exactly what I understood / assumed. Your version has all the SMT you need already installed w00t , just ignore these 2 (optional / extra) SMT pads.
Altitude909
cool. thanks!
Altitude909
alright, results!

Notes on my Mouser cart:

1; 1uF Caps are on the large side, if someone has something else that's available at mouser, I'll switch them. They fit the foot prints but CT2a/b/c is a different footprint and that one is tight,

2: Ferrite beads are big but could be made to fit like I did. Those are my go to parts and I'm not going to switch them out unless someone has a proven part that is resistor size.

3: The TI TL074 parts are abnormally long for some reason and wont fit without a socket and that's all the Mouser stocks in PTH. I lifted mine so they float about the resistor and diode at each end


Hazium
This looks like an involved build. 5+ hours I'm sure. It looks like you are soldering the IC's directly to the board. I'm new to this so I don't know all the techniques. Are there benefits to doing this, other than some saved $?
Altitude909
Not that long, it's a lot of triples so it goes quick. 4 hrs maybe. I prefer to solder the chips down, if you're not confident in your soldering, use sockets.

Are calibration instructions in the works? The JH page is a bit terse.

Also, there is no mention of where the -12V pin is, I needed to look this up since I have not dealt with a MOTM connector before and if one should use a keyed header for the euro power connector, it will be opposite of the MOTM connector footprint silkscreen
spotta
Hazium wrote:
This looks like an involved build. 5+ hours I'm sure. It looks like you are soldering the IC's directly to the board. I'm new to this so I don't know all the techniques. Are there benefits to doing this, other than some saved $?

Soldering directly is fine until you have to remove/replace/troubleshoot. Then that socket earns the 20pence it costs 1000 times over
thumbs up
spotta
What's the orientation of Q4 & Q5? or what does the square hole represent?
nordlead
spotta wrote:
What's the orientation of Q4 & Q5? or what does the square hole represent?


Square pad = Emitter (followed by B C )
spotta
nordlead wrote:
spotta wrote:
What's the orientation of Q4 & Q5? or what does the square hole represent?


Square pad = Emitter (followed by B C )
thumbs up
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