electro-music.com   Dedicated to experimental electro-acoustic
and electronic music
 
    Front Page  |  Articles  |  Radio
 |  Media  |  Forum  |  Wiki  |  Links  |  Store
Forum with support of Syndicator RSS
 FAQFAQ   CalendarCalendar   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   LinksLinks
 RegisterRegister   ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in  Chat RoomChat Room 
 Forum index » DIY Hardware and Software » YuSynth
VCO Input Voltage query
Post new topic   Reply to topic Moderators: Scott Stites
Page 1 of 1 [22 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Author Message
djfill



Joined: Jan 10, 2012
Posts: 26
Location: Cardiff, Wales, UK

PostPosted: Tue Jan 10, 2012 3:24 pm    Post subject: VCO Input Voltage query Reply with quote  Mark this post and the followings unread

Hello everyone! I'm new to the forum and to making DIY modules and hope someone can help.

I've built a YuSynth VCO (the SSM2210 version). It mostly seems to work fine, I have good wave shapes, I've not adjusted the tracking or tuning yet as I need to buy a tuner. The frequency is a little unstable however, it does seem to vary a bit if I leave it on for a while. I'm not too worried about this for now but may be a pain later on.

The main concern I have (and may be related to the unstable frequency) is that when I plug the power in, the input voltage changes from +15V -15V to +15V -29V. The power supply unplugged gives a normal +15V -15V and is stable, it's only when I power the module I get -29V. I had the same issue in the first VCO I built, but I put this down to me using incorrect components and thought I'd blown something so started again after a few days of troubleshooting.

Here's some pics that I hope may be of help:

Input DC Voltage before plugging in to module:
http://www.mediafire.com/download.php?fo7cc6r0o2uh469
http://www.mediafire.com/download.php?q58zcbni94n8f9x

Input DC Voltage with module plugged in:
http://www.mediafire.com/download.php?7a7wbnabvo047gh
http://www.mediafire.com/download.php?xg3bc527eqp23pu

Voltage at output of regulators:
http://www.mediafire.com/download.php?ajdp6adi54alcq6
http://www.mediafire.com/download.php?q55c4ospjrbwtmm

Waveforms:
http://www.mediafire.com/download.php?v9tirb5792hm2m8
http://www.mediafire.com/download.php?2zb9y3k9i29dfs1
http://www.mediafire.com/download.php?moca1te1f4o4zf4

Any help is much appreciated,

Thanks, Phil


IMG-20120113-00034.jpg
 Description:
 Filesize:  2.09 MB
 Viewed:  85 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

IMG-20120113-00034.jpg



IMG-20120113-00036.jpg
 Description:
 Filesize:  2.28 MB
 Viewed:  83 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

IMG-20120113-00036.jpg



Last edited by djfill on Fri Jan 13, 2012 11:43 am; edited 4 times in total
Back to top
View user's profile Send private message
Mongo1



Joined: Aug 11, 2011
Posts: 411
Location: Raleigh NC

PostPosted: Tue Jan 10, 2012 4:41 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi -

If you're saying (and I think you are) that your negative supply is changing from -15 to -29, then you've definitely got a problem. I would certainly not recommend plugging anything into the supply until you get this worked out.

It's not clear to me whether this is actually a power supply issue, or if you're doing something that makes the measurement inaccurate.
There is no way the VCO should be able to make your supply go to -29Volts though.

Ideally it would be good to get some low value high-wattage resistors and hang them on the power lines to load test your supply.

Gary
Back to top
View user's profile Send private message Send e-mail
Mongo1



Joined: Aug 11, 2011
Posts: 411
Location: Raleigh NC

PostPosted: Tue Jan 10, 2012 4:45 pm    Post subject: Reply with quote  Mark this post and the followings unread

BTW - I think that several of your links are duplicates. I didn't see any pictures showing -29V, and several of the pictures are the same.

Gary
Back to top
View user's profile Send private message Send e-mail
djfill



Joined: Jan 10, 2012
Posts: 26
Location: Cardiff, Wales, UK

PostPosted: Tue Jan 10, 2012 6:21 pm    Post subject: Reply with quote  Mark this post and the followings unread

Mongo1 wrote:
BTW - I think that several of your links are duplicates. I didn't see any pictures showing -29V, and several of the pictures are the same.

Gary


I've fixed the links now to show the correct images, thanks!
Back to top
View user's profile Send private message
PickNick



Joined: Oct 16, 2009
Posts: 82
Location: BP

PostPosted: Thu Jan 12, 2012 3:56 am    Post subject: Reply with quote  Mark this post and the followings unread

did you check the regulators?
78L15 and 79L15 are on the right place?
maybe there is some shorts between the +/GND/- rails.
15+15=30 > DMM say 29
better pics...?

_________________
Allow theex.nl
Back to top
View user's profile Send private message
djfill



Joined: Jan 10, 2012
Posts: 26
Location: Cardiff, Wales, UK

PostPosted: Fri Jan 13, 2012 11:46 am    Post subject: Reply with quote  Mark this post and the followings unread

PickNick wrote:
did you check the regulators?
78L15 and 79L15 are on the right place?
maybe there is some shorts between the +/GND/- rails.
15+15=30 > DMM say 29
better pics...?


Hi, I've double checked the regulators against the schematic and checked their datasheets and they are the correct way. I've also checked the board and i can't see any shorts. I've attached some better pics of the board now...

Thanks.
Back to top
View user's profile Send private message
djfill



Joined: Jan 10, 2012
Posts: 26
Location: Cardiff, Wales, UK

PostPosted: Sat Jan 14, 2012 9:18 am    Post subject: Reply with quote  Mark this post and the followings unread

ok...I'm starting to think the power supply I'm using is inadequate and is causing problems on the negative rail. Can anyone recommend a good power supply? I'm looking at a supply system from Synthersizers.com but seems a bit pricey at £210 before shipping costs from the US.

Has anyone here found a DIY kit? I might use the Q137 Power Control & Interface Module from Synthersizers.com as it looks neat, but the QPS1 Power Supply is a bit out of my price range really. Would be nice if they sold the boards...
Back to top
View user's profile Send private message
yusynth



Joined: Nov 24, 2005
Posts: 1233
Location: France

PostPosted: Sat Jan 14, 2012 9:24 am    Post subject: Reply with quote  Mark this post and the followings unread

Can you post a detailed view of your power-supply and how the the various poles of the PSU are connected together ? Is the positive pole of the negative supply (back) is connected to the negative pole of the other (front).

I doubt they are internally connected, this is why you measure -29V because the common point (0V) is missing . This means that the two PSU circuit are independant that is the positive pole of the negative PSU circuit is not connected to the negative pole of the positive PSU circuit

_________________
Yves
Back to top
View user's profile Send private message Visit poster's website
djfill



Joined: Jan 10, 2012
Posts: 26
Location: Cardiff, Wales, UK

PostPosted: Sat Jan 14, 2012 12:47 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hello Yves, thanks for the reply...

I've connected the + rail of the negative supply to the - of the positive supply as seen in the pic below. I've been lead to believe this 0V rail needs to be earthed...is this correct? As seen in the other pics, I've done this by connecting this 0V rail the mains plug earth...is this correct also?

I have more information...

I realise this -29V problem only occurs when my oscilloscope is attached. So I took my VCO out of the equation. When the earth from my oscilloscope is connected to the earth of my power supply, I get the -29V!?! So i figured the 0V rail is not earthed correctly. So I left 0V rail earthed to my power supply and adjusted the pot on my power supply to get -15V....then I got smoke, bad smells coming from the - supply.

I know this problem is now outside the remit of your VCO design, so any further help is very much appreciated. Maybe I should pay now for a long term power supply solution?

Thanks, phil.


IMG-20120114-00037.jpg
 Description:
Overall power supply wiring
 Filesize:  1.38 MB
 Viewed:  97 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

IMG-20120114-00037.jpg



IMG-20120114-00045.jpg
 Description:
Close up of AC voltage in
 Filesize:  1.14 MB
 Viewed:  89 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

IMG-20120114-00045.jpg



IMG-20120114-00039.jpg
 Description:
Close up of transformer
 Filesize:  1.19 MB
 Viewed:  93 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

IMG-20120114-00039.jpg



IMG-20120114-00041.jpg
 Description:
Close up of output voltage
 Filesize:  1.65 MB
 Viewed:  82 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

IMG-20120114-00041.jpg



internal_connection.jpg
 Description:
Underside of power supply. Please note the internal connection joining the + of the negative rail to the - of the positive rail.
 Filesize:  560.38 KB
 Viewed:  77 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

internal_connection.jpg



Last edited by djfill on Sun Jan 15, 2012 12:35 pm; edited 2 times in total
Back to top
View user's profile Send private message
yusynth



Joined: Nov 24, 2005
Posts: 1233
Location: France

PostPosted: Sat Jan 14, 2012 1:30 pm    Post subject: Reply with quote  Mark this post and the followings unread

That's what I suspected the two PSU are independent you must interconnect them to define the 0V reference.
On your PSU you have one output labelled+ that you left free. You must connect it to the 0V of the modules that is connect it to the point where is attached the green wire (0V of the other PSU line).

_________________
Yves
Back to top
View user's profile Send private message Visit poster's website
djfill



Joined: Jan 10, 2012
Posts: 26
Location: Cardiff, Wales, UK

PostPosted: Sat Jan 14, 2012 4:07 pm    Post subject: Reply with quote  Mark this post and the followings unread

yusynth wrote:
That's what I suspected the two PSU are independent you must interconnect them to define the 0V reference.
On your PSU you have one output labelled+ that you left free. You must connect it to the 0V of the modules that is connect it to the point where is attached the green wire (0V of the other PSU line).


Hi Yves,

I've already done the internal connection. I've highlighted this now on the picture above. I'm just not sure if I've earthed this point correctly.
Back to top
View user's profile Send private message
djfill



Joined: Jan 10, 2012
Posts: 26
Location: Cardiff, Wales, UK

PostPosted: Sat Jan 14, 2012 4:13 pm    Post subject: Reply with quote  Mark this post and the followings unread

p.s. do you think this supply and transformer is suitable? Do you have any suggestions for a good power supply for around 22 modules?

Thanks.
Back to top
View user's profile Send private message
PickNick



Joined: Oct 16, 2009
Posts: 82
Location: BP

PostPosted: Sat Jan 14, 2012 8:27 pm    Post subject: Reply with quote  Mark this post and the followings unread

6VA means 6watt...
max load 3VA per winding!
if its true than this PSU really small to drive 20 modules.
you need around 50VA 2x 18V/// if you need a stable +/- 15V
i bought some toroid from this distributor>>>
http://www.tme.eu/html/EN/toroidal-transformers-with-dual-output-voltage-55xxx-p1s2-series/ramka_6812_EN_pelny.html

55122-P1S2

some calculation:
50VA > 50Watt
50VA/18v= 2.777777778Amp
2.78/2=~1.39Amp
than you have 1.38amp/rails

this toroid would be good for drive more than 20 modules.
hope this hlp!

_________________
Allow theex.nl
Back to top
View user's profile Send private message
yusynth



Joined: Nov 24, 2005
Posts: 1233
Location: France

PostPosted: Sun Jan 15, 2012 2:04 am    Post subject: Reply with quote  Mark this post and the followings unread

djfill wrote:
I've already done the internal connection. I've highlighted this now on the picture above. I'm just not sure if I've earthed this point correctly.

You'd did it but have you checked with an ohm-meter (at power off) that they are actually connected ? You should measure 0 ohm between the two expected common poles.

_________________
Yves
Back to top
View user's profile Send private message Visit poster's website
yusynth



Joined: Nov 24, 2005
Posts: 1233
Location: France

PostPosted: Sun Jan 15, 2012 2:11 am    Post subject: Reply with quote  Mark this post and the followings unread

Concerning the power of the transformer it is certainly too small, you need at least a 2x18V 26VA for 22 modules.
You can calculate exactly what you need for yusynth module with this spreadsheet :
Excel spreadsheet

_________________
Yves
Back to top
View user's profile Send private message Visit poster's website
djfill



Joined: Jan 10, 2012
Posts: 26
Location: Cardiff, Wales, UK

PostPosted: Sun Jan 15, 2012 8:56 am    Post subject: Reply with quote  Mark this post and the followings unread

Yves...excel sheet is very handy, thanks very much. Yes the transformer is small, I was just using this setup to build and test individual modules.

I've tested the connectivity between the two rails incase of a dry joint, but it they're definitely connected.

PickNick...thanks for the link this is really helpful and cheap too!! Very Happy
Do you have any further suggestions for a suitable +15V -15V power supply to go with this?


IMG-20120115-00048.jpg
 Description:
Showing a diode test between the two rails...what you can't hear here is the beeping noise!
 Filesize:  1.34 MB
 Viewed:  78 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

IMG-20120115-00048.jpg


Back to top
View user's profile Send private message
yusynth



Joined: Nov 24, 2005
Posts: 1233
Location: France

PostPosted: Sun Jan 15, 2012 9:12 am    Post subject: Reply with quote  Mark this post and the followings unread

May be the regulator of your negative PSU is dead... replace it if you have a spare part.
_________________
Yves
Back to top
View user's profile Send private message Visit poster's website
djfill



Joined: Jan 10, 2012
Posts: 26
Location: Cardiff, Wales, UK

PostPosted: Sun Jan 15, 2012 9:18 am    Post subject: Reply with quote  Mark this post and the followings unread

Maybe...at least I know my board is good, so I guess I'll move on to looking for a more permanent power supply as I'm starting to build the case soon. Any suggestions Yves?

Thanks, Phil.
Back to top
View user's profile Send private message
Mongo1



Joined: Aug 11, 2011
Posts: 411
Location: Raleigh NC

PostPosted: Sun Jan 15, 2012 10:21 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi Dj,

I don't know if you'd be comfortable doing this, but I just went on Ebay and bought a surplus supply. There are lots of them floating around.

If you would like to have a 'bench' supply to test individual modules, musicfromouterspace has some nice inexpensive options.

Gary
Back to top
View user's profile Send private message Send e-mail
djfill



Joined: Jan 10, 2012
Posts: 26
Location: Cardiff, Wales, UK

PostPosted: Sun Jan 15, 2012 12:11 pm    Post subject: Reply with quote  Mark this post and the followings unread

Mongo1 wrote:
Hi Dj,

I don't know if you'd be comfortable doing this, but I just went on Ebay and bought a surplus supply. There are lots of them floating around.

If you would like to have a 'bench' supply to test individual modules, musicfromouterspace has some nice inexpensive options.

Gary


Thanks, just had a quick look but couldn't see any. What should I search for?
Back to top
View user's profile Send private message
djfill



Joined: Jan 10, 2012
Posts: 26
Location: Cardiff, Wales, UK

PostPosted: Sun Jan 15, 2012 12:21 pm    Post subject: *** FAULT FOUND ***
Subject description: Issue resolved
Reply with quote  Mark this post and the followings unread

Thanks for all your help and responses, I've found the issue with this supply.

The 0V rail on the power supply was not earthed. Not only that but the negative regulator was earthed instead. There are two rails next to each other that I thought were joined and a hole in each rail that I thought I could take my pick to put the earth wire in. No! Not the case. They were not joined and i earthed the wrong rail.

I will highlight the picture showing the underside of the supply. On the right, I've circled the incorrect place for the earth wire in red and circle where it needed to go in blue.

I little embarrassed? Yes. Deterred? No. This is not the first and won't be the last mistake I make during this project.

Thanks, Phil.
Back to top
View user's profile Send private message
Mongo1



Joined: Aug 11, 2011
Posts: 411
Location: Raleigh NC

PostPosted: Sun Jan 15, 2012 12:32 pm    Post subject: Reply with quote  Mark this post and the followings unread

That's great news Phil -
I'm glad to see that can-do attitude. With this kind of a hobby you really need it.

The other day I was talking to a friend about this whole synth-building experience. I told him "I learn a little something from every mistake I make. I just don't know how much more knowledge I can afford"

Regarding Ebay - I think I just used "power supply dual 15V". I just checked and found a few candidate here in the US. There's a company called Meanwell that seems to be pretty popular out there, and of course Power-one makes good stuff.

Gary
Back to top
View user's profile Send private message Send e-mail
Display posts from previous:   
Post new topic   Reply to topic Moderators: Scott Stites
Page 1 of 1 [22 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
 Forum index » DIY Hardware and Software » YuSynth
Jump to:  

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
e-m mkii

Please support our site. If you click through and buy from
our affiliate partners, we earn a small commission.


Forum with support of Syndicator RSS
Powered by phpBB © 2001, 2005 phpBB Group
Copyright © 2003 through 2009 by electro-music.com - Conditions Of Use