electro-music.com   Dedicated to experimental electro-acoustic
and electronic music
 
    Front Page  |  Radio
 |  Media  |  Forum  |  Wiki  |  Links
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 
go to the radio page Live at electro-music.com radio 1 Please visit the chat
poster
 Forum index » DIY Hardware and Software » Lunettas - circuits inspired by Stanley Lunetta
LC-tank bass drums
Post new topic   Reply to topic Moderators: mosc
Page 1 of 1 [3 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Author Message
elektrouwe



Joined: May 27, 2012
Posts: 143
Location: Germany

PostPosted: Sat Aug 30, 2014 4:32 pm    Post subject: LC-tank bass drums
Subject description: from theory to working circuit
Reply with quote  Mark this post and the followings unread

I recently got a donation of some 100 small power transformers. Because I don't need so many power supplies, I wondered if I could use the primary winding as a big L, add a small C. in parallel and have it resonate in the audio range.
Pic.1 shows an LC-tank simulation : L is 20H, copper windings have 1Ohm and C is 100nF. As you can see it's a really mighty base drum with a decay time in the minute range ! Unfortunately a 20H coil with 1Ohm resistance needs a lot of windings with fat wire. Although I did not mind the 100kg weight and the size of a washing machine, I decided to continue experimenting with my transformers...
Ok, reality check : Pic.2 shows the simulation with measured data from the primary winding of my 1VA, 230V:6V transformers.
L is still 20H, but a size of 2x2x3 cm3 cries for thin wire: 2kOhm is a lot, and this leads to a bass burst of only 0.1 secs Sad
Ok, we have to fight the 2k. I knew a circuit called "negative impedance converter" with the nickname NIC. It' made of a non-inverting amplifier with positive feedback.
Pic.3 shows the bad LC-tank from pic.2 with a NIC build with 1 opamp , 1 R for the positive feedback and a 100k potentiometer to adjust gain.
As you can see, the compensation works and let us control the damping between very short bass bursts (uncompensated) and oscillation (overcompensated) ! finding the narrow sweet spot with the pot. to get a nice 0.5 ..1 sec tone is not so easy, but I can accept it for such a simple circuit.
Last step was to realize it in Lunetta style : in pic.4 the opamp has been replaced by 2 inverting CMOS amps and a 3rd inverted is used for a 2nd distorted output than can be mixed with the clean sine of the LC-tank.
Have fun !


LC_bass1.jpg
 Description:
 Filesize:  78.56 KB
 Viewed:  264 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

LC_bass1.jpg



LC_bass2.jpg
 Description:
 Filesize:  88.4 KB
 Viewed:  276 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

LC_bass2.jpg



LC_bass3.jpg
 Description:
 Filesize:  212.29 KB
 Viewed:  274 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

LC_bass3.jpg


Back to top
View user's profile Send private message
L´Andratté



Joined: Sep 23, 2012
Posts: 150
Location: Hamburg, Germany
Audio files: 5

PostPosted: Thu Oct 16, 2014 3:31 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi electrouwe! That´s very Cool
You could build a decent transformer gamelan with your stack.
Where´s your mentioned pic.4? I´d like to see it.
And hear it!
Curious how all that copper sounds Shocked
Back to top
View user's profile Send private message
elektrouwe



Joined: May 27, 2012
Posts: 143
Location: Germany

PostPosted: Thu Oct 16, 2014 4:32 am    Post subject: Reply with quote  Mark this post and the followings unread

L´Andratté wrote:
..Where´s your mentioned pic.4?

oops, don't know how it got lost, here it comes...

I cant' attach a sound file right now, because I removed the prototype from breadboard. I designed a quad-bass-drum PCB meanwhile, but I didn't etch it yet. Have it on my home PC, can post it tommorow if you are interested.


LC_bass4.jpg
 Description:
 Filesize:  175.87 KB
 Viewed:  255 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

LC_bass4.jpg


Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic Moderators: mosc
Page 1 of 1 [3 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 » Lunettas - circuits inspired by Stanley Lunetta
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


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