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 » MusicFromOuterSpace.com designs by Ray Wilson
mfos 10step vs. 16 step sequencer advice
Post new topic   Reply to topic Moderators: dnny, Uncle Krunkus, v-un-v
Page 2 of 2 [31 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Goto page: Previous 1, 2
Author Message
jukingeo



Joined: Oct 24, 2007
Posts: 161
Location: The dark side of the moon

PostPosted: Tue Oct 01, 2013 10:41 am    Post subject: Reply with quote  Mark this post and the followings unread

ashleym wrote:
Dont worry, I am sure I am the one not being very clear.


Nah, I probably read it the wrong way. I am probably sure you thought something was wrong when I mentioned getting a switch on each channel. LOL!

Quote:

I have a switch to set the overall voltage range. I wired the switch to the analogue board. Look around VS1 that sets the control voltage into U1-A of the TL084. It has the usual two resistors R25 and R26, 200 and 100k respectively. A quick calculate

Amplification, voltage= (R25+R26)/R26 or (200+100)/100

gives you the 3x gain for the 2.5v source= 7.5 volts Ray mentions.

So if you switch one of these resistors, I used R25, between 10K, 100K & 200k, you roughly get unity gain with the 10K (2.5v ish), 2x gain with the 100K (5v) or the existing 3x gain with 200k (7.5v).


I am looking at the schematic now. Yes, I see R-25 the U1-A feedback resistor that is in parallel with the cap, right?

Quote:

On the circuit diagram, dont connect R25. Put one end of a lead in position 1 of R25. The other end of the lead goes to the in of a 3 way rotary switch. Wire the 10/100/200K resistors to each of the outs of the switch. Tie all the ends of the resistors together and solder into position 2 of R25.


Sounds good! Rotary switches can run a pretty penny, though. I think you could do the same with using a standard SPDT center off switch and put the necessary resistors in parallel to net the values you presented.

Quote:

I hope that helps.

Quote:
U1-A in conjunction with VS1 (LM336-2.5V 2.5 volt precision voltage reference) create a 7.5 volt source to which one side of all of the pots are connected. The precision voltage source applies a very clean 2.5V to the non-inverting input of U1-A. Feedback resistor R25 (200K) and gain set resistor R26 (100K) set the gain around U1-A to 3 which is how we get 7.5V from the 2.5V reference.


Yes, it does help.

Thank You,

Geo


Mongo1 wrote:
Sorry I didn't get back to you earlier - It sounds like you've got it sussed out though.

I originally did the range modification on the hexinverter sympleSeq. On that one it's a breeze - There's an output resistor between the op-amp and the jack, so you just need to solder another resistor between the output jack and the ground. It makes a voltage divider, and it works great.

Gary


Is this on the analog board schematic? I don't see a resistor on the CV output jacks here...the output of each op amp goes directly to the output jack.

http://www.musicfromouterspace.com/analogsynth_new/SEQ16_2006/seq16schematicpage4.gif

Thanx,

Geo
Back to top
View user's profile Send private message
ashleym



Joined: Aug 20, 2009
Posts: 179
Location: uk

PostPosted: Tue Oct 01, 2013 2:03 pm    Post subject: Reply with quote  Mark this post and the followings unread

You ARE correct. SO am I. We all are correct Very Happy Very Happy Very Happy Very Happy Very Happy Very Happy

Yup thats the correct resistor. A rocker with will work well too. Dont be afraid to experiment with the values. Try and wire the switch so it makes sense, ie with the switch in the up position you get the highest voltage or whatever makes sense to you. How about wiring a dpdt switch and wire the resistors across the tags?

_________________
http://soundcloud.com/for-mash-get-ash
Back to top
View user's profile Send private message
jukingeo



Joined: Oct 24, 2007
Posts: 161
Location: The dark side of the moon

PostPosted: Tue Oct 01, 2013 5:14 pm    Post subject: Reply with quote  Mark this post and the followings unread

ashleym wrote:
You ARE correct. SO am I. We all are correct Very Happy Very Happy Very Happy Very Happy Very Happy Very Happy

Yup thats the correct resistor. A rocker with will work well too. Dont be afraid to experiment with the values. Try and wire the switch so it makes sense, ie with the switch in the up position you get the highest voltage or whatever makes sense to you.


Well, unfortunately going the parallel resistor route on a SPDT C/O would dictate the highest resistance, the 200k would be in the center off position. One position would put another 200k in parallel which would give you the 100k position. Putting a 10k resistor on the other leg would be about 9.5k which would be sufficient there. But yes, that would mean the ranges would be mixed up on the front panel going something like Low, High, Med.

Quote:

How about wiring a dpdt switch and wire the resistors across the tags?


Sorry, I don't quite follow you there.

Geo
Back to top
View user's profile Send private message
ashleym



Joined: Aug 20, 2009
Posts: 179
Location: uk

PostPosted: Wed Oct 02, 2013 2:40 am    Post subject: Reply with quote  Mark this post and the followings unread

With a DPDT switch with terminals like this

1 4
2 5
3 6


wire in to terminal 2. Put a 200K between 2 and 5. A 200K between 1 and 4. A 10K between 3 and 6. Wire out to terminal 5.

With the switch in OFF, the signal goes straight through the 200K resistor via terminals 2 & 5. With the switch UP the signal sees two 200K resistors in parallel giving 100K. With the switch DOWN the signal sees a 200K and a 10K in parallel giving about 9.5K.


Sorry, I know this is a repeat of what you have just said. I replied before i reread your post. YES you will end up with the switch "not making sense" in terms of its position, I am trying to figure out in my head it there is a way you can cross the resistors path to to this, ie going from terminal 2 to 6 and 3 to 5 to shuffle the values around.......see how easy it is to use a rotary!!

_________________
http://soundcloud.com/for-mash-get-ash
Back to top
View user's profile Send private message
ashleym



Joined: Aug 20, 2009
Posts: 179
Location: uk

PostPosted: Wed Oct 02, 2013 3:03 am    Post subject: Reply with quote  Mark this post and the followings unread

Because we have to use two 200Ks to give us the 100k there is a symmetry and so no amount of switching around I do is making the switch make sense. I have failed you Embarassed Embarassed Embarassed Embarassed Embarassed
_________________
http://soundcloud.com/for-mash-get-ash
Back to top
View user's profile Send private message
jukingeo



Joined: Oct 24, 2007
Posts: 161
Location: The dark side of the moon

PostPosted: Thu Oct 03, 2013 5:49 pm    Post subject: Reply with quote  Mark this post and the followings unread

ashleym wrote:
With a DPDT switch with terminals like this

1 4
2 5
3 6


wire in to terminal 2. Put a 200K between 2 and 5. A 200K between 1 and 4. A 10K between 3 and 6. Wire out to terminal 5.

With the switch in OFF, the signal goes straight through the 200K resistor via terminals 2 & 5. With the switch UP the signal sees two 200K resistors in parallel giving 100K. With the switch DOWN the signal sees a 200K and a 10K in parallel giving about 9.5K.


Sorry, I know this is a repeat of what you have just said. I replied before i reread your post. YES you will end up with the switch "not making sense" in terms of its position, I am trying to figure out in my head it there is a way you can cross the resistors path to to this, ie going from terminal 2 to 6 and 3 to 5 to shuffle the values around.......see how easy it is to use a rotary!!


LOL! Yes, that IS kind of the same thing except that with the way I described it, you would tie all the resistors together on one side. The 200k goes to the center terminal of an SPDT switch. Then each leg of the switch would put the other 200k and 10k resistors in the circuit respectively. While both of our cases will work the thing is that you still will have the out of place order on the switch. You would either have 2.5, 7.5, & 5v or 5v, 7.5, & 5v. You can't really get away with that because the highest value resistor MUST be in the center off position.

So yes, that would be the advantage of the rotary switch as you can keep the increasing voltage range order, but you add to the cost of the build via the higher priced rotary switch in addition, you need a knob. I think for me, I will live with the obtuse range arrangement.

Unless...I think with your DPDT switch there MIGHT be a way to get the order if you go with a series/parallel switching arrangement. But I have to put on my thinking cap for that one.

...to be continued.

Geo
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic Moderators: dnny, Uncle Krunkus, v-un-v
Page 2 of 2 [31 Posts]
View unread posts
View new posts in the last week
Goto page: Previous 1, 2
Mark the topic unread :: View previous topic :: View next topic
 Forum index » DIY Hardware and Software » MusicFromOuterSpace.com designs by Ray Wilson
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
AmbiphonicDSP

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