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 » Rob Hordijk DIY Designs
Benjolin Osc problem
Post new topic   Reply to topic Moderators: Rob
Page 1 of 1 [5 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Author Message
oscilloclast



Joined: Sep 29, 2005
Posts: 49
Location: VA

PostPosted: Wed Nov 25, 2009 2:54 pm    Post subject: Benjolin Osc problem
Subject description: Benjolin Osc problem
Reply with quote  Mark this post and the followings unread

Rob,

The output of Osc 2 is a downward sloping ramp (it should be a triangle) and a very weak pulse (it should be stronger like the pulse out on Osc 1). Any suggestions on where the problem may be? All of my IC's have sockets and I have replacements for all of them (if I need to switch them).

Thanks,
David
Back to top
View user's profile Send private message Visit poster's website
State Machine
Janitor
Janitor


Joined: Apr 17, 2006
Posts: 2745
Location: New York
Audio files: 24

PostPosted: Fri Dec 04, 2009 2:15 pm    Post subject: Reply with quote  Mark this post and the followings unread

As is the case most of the time, bad IC's are usually not the casue of a problem but more a wrong value component surrounding them. Try the simple thing and check the components in each oscillator one for one as they are identical circuits .. for example ..... R12 and R5, R6 and R13 ... ect ....

Also, check for "bent under" pins on IC2, 6, and 3 ....

After you check that these components are correct .... then check for solder bridges around these components to make sure they are ONLY connected to where there supposed to be. ... if thats good .. then ......

on U3 pins 5 and 2 .. with power OFF, check that they are connected together and to ground. This is the reference to the output amplifier that creates the pulse , P2 ....

Lets try these things first ....

Bill
Back to top
View user's profile Send private message Send e-mail
oscilloclast



Joined: Sep 29, 2005
Posts: 49
Location: VA

PostPosted: Sat Dec 05, 2009 9:17 am    Post subject: Reply with quote  Mark this post and the followings unread

Bill,

Thanks for the tips. I actually replaced all of the chips (I used sockets when I built it) but the problem turned out to be some switched resistors. The output waves are correct now but I'm getting +/- 5v on bth triangles and +/- 10v on both pulse (so I need to look into this descrepency).

Thanks,
David
Back to top
View user's profile Send private message Visit poster's website
State Machine
Janitor
Janitor


Joined: Apr 17, 2006
Posts: 2745
Location: New York
Audio files: 24

PostPosted: Sat Dec 05, 2009 5:33 pm    Post subject: Reply with quote  Mark this post and the followings unread

Good news ... Very Happy BTW, the pulse will be larger in amplitude than the triangle waves so there is nothing wrong. The TRI waveforms feed an approximately 9 dB amplifier stage so that is OK ...

The pulse output is feed back via the 100K resistor (R3/R10) into the OTA to reverse the current into the integrator ...

With a split 9V supply (+9V/-9V), you would not get any more then 18V P-P ideally but the TL074 does not go to the rail so it;s something less. I say this because you mentioned that you had +10/-10 and that equates to 20V P-P, unless I misunderstood what you said??

Bill
Back to top
View user's profile Send private message Send e-mail
oscilloclast



Joined: Sep 29, 2005
Posts: 49
Location: VA

PostPosted: Sun Dec 06, 2009 9:15 pm    Post subject: Reply with quote  Mark this post and the followings unread

Yep your right, I should have said +/- 8v.

Thanks,
David
Back to top
View user's profile Send private message Visit poster's website
Display posts from previous:   
Post new topic   Reply to topic Moderators: Rob
Page 1 of 1 [5 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 » Rob Hordijk DIY Designs
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