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 » Thomas Henry designs
An Analog Synthesizer for the 21st Century
Post new topic   Reply to topic Moderators: Scott Stites
Page 3 of 8 [178 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, 3, 4, 5, 6, 7, 8 Next
Author Message
chieffrancis



Joined: Feb 07, 2013
Posts: 88
Location: california, united states

PostPosted: Sat Mar 23, 2013 3:28 pm    Post subject: Reply with quote  Mark this post and the followings unread

It's a keystation 49e by m-audio. I see that it has a resistor network so I assume that there is some sort of CV going on. There's a MIDI and USB output for they keyboard.
Back to top
View user's profile Send private message
elmegil



Joined: Mar 20, 2012
Posts: 1516
Location: Chicago
Audio files: 14

PostPosted: Sat Mar 23, 2013 6:54 pm    Post subject: Reply with quote  Mark this post and the followings unread

That's all going to be handled by whatever microprocessor is in the beast. Which doesn't mean it isn't generating CVs internally, but that'll make it a bit harder to figure out what's what since there's no audio circuitry for you to tap into and see what's going on.

I have no luck finding schematics.
Back to top
View user's profile Send private message
fonik



Joined: Jun 07, 2006
Posts: 3760
Location: Germany
Audio files: 23

PostPosted: Sun Mar 24, 2013 1:57 pm    Post subject: Reply with quote  Mark this post and the followings unread

chieffrancis wrote:
It's a keystation 49e by m-audio. I see that it has a resistor network so I assume that there is some sort of CV going on. There's a MIDI and USB output for they keyboard.

what i see are quite a few diodes mounted directly to the actual keyboard PCB.

in general there are two different types of synth keyboards, resistor network (old), and diode network (today synths and MIDI controllers).

obviously your keyboard is the latter, a diode matrix keybaord. all you need is to figuire out the pin out of the diode matrix and add a scanner circuit.

for the latter 3 scanners come to my mind, the MFOS, the thomas henry (!) keyboard scanner (can be found in one of his older books), and the IKC, which is a modern micro controller based reincarnation of thomas' old circuit.

_________________
Posted Image, might have been reduced in size. Click Image to view fullscreen.
cheers,
matthias
____________
fonitronik at
FlickR (pix) / SoundCloud (sounds) / YouTube (vids) / Vimeo (vids) / facebook (news)
Back to top
View user's profile Send private message Send e-mail Visit poster's website
chieffrancis



Joined: Feb 07, 2013
Posts: 88
Location: california, united states

PostPosted: Tue Mar 26, 2013 9:07 pm    Post subject: Reply with quote  Mark this post and the followings unread

fonik wrote:
chieffrancis wrote:
It's a keystation 49e by m-audio. I see that it has a resistor network so I assume that there is some sort of CV going on. There's a MIDI and USB output for they keyboard.

what i see are quite a few diodes mounted directly to the actual keyboard PCB.

in general there are two different types of synth keyboards, resistor network (old), and diode network (today synths and MIDI controllers).

obviously your keyboard is the latter, a diode matrix keybaord. all you need is to figuire out the pin out of the diode matrix and add a scanner circuit.

for the latter 3 scanners come to my mind, the MFOS, the thomas henry (!) keyboard scanner (can be found in one of his older books), and the IKC, which is a modern micro controller based reincarnation of thomas' old circuit.


Thanks for the info man.

I sent a PM to Bill hoping I could get a little more technical info about the order and IKC stuff.

How exactly would I be able to identify the diode pin out of the entire diode matrix? Would that pin be the last diode coming from the diode matrix or would it be a little closer to some of the other boards that are serially connected?

Are there any components in particular that I could be on the lookout for that would help identify that pin out? And how exactly is the pin out to be connected to a scanner circuit? Does the scanner circuit output the 1V/Oct, gate/trigger signals or is it more like a converter/translator between the keyboard and the VCOs and other modules?

Thanks!

I love this forum...everyone is so informative and helpful!
Back to top
View user's profile Send private message
chieffrancis



Joined: Feb 07, 2013
Posts: 88
Location: california, united states

PostPosted: Thu Mar 28, 2013 9:30 pm    Post subject: Reply with quote  Mark this post and the followings unread

Does anyone happen to know what those "legs" are called on the corners of perfboards?

Does anyone know how "normally closed/open" terminals on SPST/DPDT switches work and if they are interchangeable?

Does anyone know the simplest way of supplying the +/-15V and +5V supplies to the synth (perhaps a prebuilt circuit/power supply/transformer circuit)?

Does anyone know additional ways on how to get the coveted 2k ohm thermistors since magsmoke hasn't been responding to my e-mails?

Thanks for all your helps guys!
Back to top
View user's profile Send private message
chieffrancis



Joined: Feb 07, 2013
Posts: 88
Location: california, united states

PostPosted: Thu Mar 28, 2013 9:36 pm    Post subject: Reply with quote  Mark this post and the followings unread

chieffrancis wrote:
Does anyone know additional ways on how to get the coveted 2k ohm thermistors since magsmoke hasn't been responding to my e-mails?


Also, does anyone know if these are NTC or PTC thermistors in Thomas's design?

Also concerning the thermistors, does anyone know how the 3500ppm/degree C translates to operating temperature range/power rating/tolerance?

I'm not quite sure on what the 3500ppm specification entails for thermistor..

I think once I obtain these, testing and assembly may begin!

PS. Damn, I did not think I would spend a grand on this project, but I have, not including panels and the IKC kit I'm planning on getting (should the moderator for the IKC kit get back to my e-mail...) hopefully. This project is definitely not for the faint of heart, but I press on.
Back to top
View user's profile Send private message
elmegil



Joined: Mar 20, 2012
Posts: 1516
Location: Chicago
Audio files: 14

PostPosted: Thu Mar 28, 2013 10:16 pm    Post subject: Reply with quote  Mark this post and the followings unread

chieffrancis wrote:
Does anyone happen to know what those "legs" are called on the corners of perfboards?


Standoffs?

Quote:

Does anyone know how "normally closed/open" terminals on SPST/DPDT switches work and if they are interchangeable?


Not clear what you're asking.


Quote:

Does anyone know the simplest way of supplying the +/-15V and +5V supplies to the synth (perhaps a prebuilt circuit/power supply/transformer circuit)?


Building the power supply from the first part of Analog Synth for the 21st Century? Smile

Or you can spend $75 - $100 on a Power One supply that has all three voltages.

Quote:

Does anyone know additional ways on how to get the coveted 2k ohm thermistors since magsmoke hasn't been responding to my e-mails?


Patience, grasshopper Smile Tim will respond, but it may take some time.

Quote:

Also, does anyone know if these are NTC or PTC thermistors in Thomas's design?


Given Thomas' description, "+3500ppm/°C thermistor" I believe they are PTC (the +).

Quote:

Also concerning the thermistors, does anyone know how the 3500ppm/degree C translates to operating temperature range/power rating/tolerance?


I don't know that power rating or tolerance are major factors, and the ppm definitely doesn't reflect anything about that. The ones Tim sells are 1/8 Watt, I've also seen bigger (I believe 1/4 Watt, but they could be 1/2 Watt given how large they are, relatively).
Back to top
View user's profile Send private message
chieffrancis



Joined: Feb 07, 2013
Posts: 88
Location: california, united states

PostPosted: Thu Mar 28, 2013 10:29 pm    Post subject: Reply with quote  Mark this post and the followings unread

Haha, I guess I'm just at that mid-semester crisis point!

Concerning the switches, say a DPDT switch, has 6 terminals, 3 dedicated to each switch. I know the middle terminal is always active and the other two pins are n.o. or n.c. My question is basically, how are these 2 pins connected as illustrated in the schematic? The switches I ordered don't have n.o./n.c. labels, of course raising concerns about how to actually connect it. I've been doing some research online and it seems that the 2 pins shouldn't be dedicated to n.o./n.c. terminals but rather indicate the typical positioning of the switch. I'm thinking that either terminal could be used as n.o./n.c. and thus are interchangeable..but I could be wrong!

I just might buy that power one power supply if my project starts cutting real close to the due-date!

I paypal'd Tim, so I must play the waiting game! I guess I'm just getting ansy, haha..

By the way, does anyone know a good place to get breadboards? I saw this breadboard by my local electronics shop that was like 4 regular ones combined (that cost me $5 each 4 years ago, but now are $10! Sad ) that went for $80! D: Yikes! I might have to just head back to eBay haha.

Thanks as usual man!
Back to top
View user's profile Send private message
chieffrancis



Joined: Feb 07, 2013
Posts: 88
Location: california, united states

PostPosted: Thu Mar 28, 2013 10:33 pm    Post subject: Reply with quote  Mark this post and the followings unread

One more thing, can the synth be directly connected to a speaker from the VCA or does it need an external amplifier and cabinet/speaker for true output?

And Tim said he put in the order and that I should get them before the weekend! Very Happy
Back to top
View user's profile Send private message
elmegil



Joined: Mar 20, 2012
Posts: 1516
Location: Chicago
Audio files: 14

PostPosted: Fri Mar 29, 2013 6:32 am    Post subject: Reply with quote  Mark this post and the followings unread

chieffrancis wrote:

Concerning the switches, say a DPDT switch, has 6 terminals, 3 dedicated to each switch. I know the middle terminal is always active and the other two pins are n.o. or n.c. My question is basically, how are these 2 pins connected as illustrated in the schematic? The switches I ordered don't have n.o./n.c. labels, of course raising concerns about how to actually connect it. I've been doing some research online and it seems that the 2 pins shouldn't be dedicated to n.o./n.c. terminals but rather indicate the typical positioning of the switch. I'm thinking that either terminal could be used as n.o./n.c. and thus are interchangeable..but I could be wrong!


In my experience, the only "normally open" or "normally closed" devices I see are jacks with switches in them, and there are some of those in Thomas' schematics. I guess a momentary switch would be n.o. or n.c. as well. Otherwise, that doesn't make much sense. The switches are wired so that when they are in one position, they indicate what that position does, and when they're in the other, they indicate what THAT position does. Note that the toggle will point one way and the opposite pair of contacts will be closed.


Quote:

By the way, does anyone know a good place to get breadboards? I saw this breadboard by my local electronics shop that was like 4 regular ones combined (that cost me $5 each 4 years ago, but now are $10! Sad ) that went for $80! D: Yikes! I might have to just head back to eBay haha.


Here's what I have (though I got them on a sale where they were cheaper yet) http://www.mcmelectronics.com/product/72-345&green=62AA5B01-280D-521D-B52A-C18AE1D248FB


Quote:

One more thing, can the synth be directly connected to a speaker from the VCA or does it need an external amplifier and cabinet/speaker for true output?


Output impedance is not such that you can drive speakers directly and get good results. You need some sort of amp.

Quote:

And Tim said he put in the order and that I should get them before the weekend!

Thanks as usual man!


Excellent news, and you're quite welcome Smile
Back to top
View user's profile Send private message
chieffrancis



Joined: Feb 07, 2013
Posts: 88
Location: california, united states

PostPosted: Fri Mar 29, 2013 6:43 pm    Post subject: Reply with quote  Mark this post and the followings unread

[quote="elmegil"]
chieffrancis wrote:

In my experience, the only "normally open" or "normally closed" devices I see are jacks with switches in them, and there are some of those in Thomas' schematics. I guess a momentary switch would be n.o. or n.c. as well. Otherwise, that doesn't make much sense. The switches are wired so that when they are in one position, they indicate what that position does, and when they're in the other, they indicate what THAT position does. Note that the toggle will point one way and the opposite pair of contacts will be closed.


So from what I understand, with the DPDT switch, I can wire either non-center terminals as I please as long as the terminals are correctly connected to the corresponding input pins of the sub-circuit I'm attaching?
Back to top
View user's profile Send private message
elmegil



Joined: Mar 20, 2012
Posts: 1516
Location: Chicago
Audio files: 14

PostPosted: Fri Mar 29, 2013 8:17 pm    Post subject: Reply with quote  Mark this post and the followings unread

Yes. Smile
Back to top
View user's profile Send private message
chieffrancis



Joined: Feb 07, 2013
Posts: 88
Location: california, united states

PostPosted: Sat Mar 30, 2013 2:43 pm    Post subject: Reply with quote  Mark this post and the followings unread

What's the best way to temporarily replace a potentiometer?

Say I need a 100k pot but I wanna put a 100k ohm resistor there temporarily, in order to test other portions of the circuit without having to deal with pottennae? From the circuit, it shows that 3 pins are connected to the pot, two to positive and negative voltage sources and the arrow pin going backwardly out to the rest of the circuit.
Back to top
View user's profile Send private message
chieffrancis



Joined: Feb 07, 2013
Posts: 88
Location: california, united states

PostPosted: Sat Mar 30, 2013 3:02 pm    Post subject: Reply with quote  Mark this post and the followings unread

I got some small breadboards but they came with metal plates, the same size.

Does anyone know the function of these?

I've used one breadboard my entire undergrad career and have never needed a metal plate. I have noticed that all the breadboards (even the one that I used freshman year) have adhesive films on the bottom also.

Just curious.
Back to top
View user's profile Send private message
elmegil



Joined: Mar 20, 2012
Posts: 1516
Location: Chicago
Audio files: 14

PostPosted: Sat Mar 30, 2013 7:36 pm    Post subject: Reply with quote  Mark this post and the followings unread

chieffrancis wrote:
What's the best way to temporarily replace a potentiometer?

Say I need a 100k pot but I wanna put a 100k ohm resistor there temporarily, in order to test other portions of the circuit without having to deal with pottennae? From the circuit, it shows that 3 pins are connected to the pot, two to positive and negative voltage sources and the arrow pin going backwardly out to the rest of the circuit.


That's wired as a voltage divider, not a really good way to deal with it. If you want to test with the voltage at either extreme, you can jumper the two pins. Otherwise, you'd need two resistors, one from +V to center and the other form -V (or gnd) to center.

If it's wired as a rheostat, that's much easier, you can put a single resistor in place.


Re: metal plate, probably means for the breadboard to be stuck to it. The larger ones are screwed down rather than using adhesive, but yes, it is common for them to have adhesive on the bottom.
Back to top
View user's profile Send private message
chieffrancis



Joined: Feb 07, 2013
Posts: 88
Location: california, united states

PostPosted: Sat Mar 30, 2013 7:42 pm    Post subject: Reply with quote  Mark this post and the followings unread

elmegil wrote:


That's wired as a voltage divider, not a really good way to deal with it. If you want to test with the voltage at either extreme, you can jumper the two pins. Otherwise, you'd need two resistors, one from +V to center and the other form -V (or gnd) to center.

If it's wired as a rheostat, that's much easier, you can put a single resistor in place.


Re: metal plate, probably means for the breadboard to be stuck to it. The larger ones are screwed down rather than using adhesive, but yes, it is common for them to have adhesive on the bottom.


I assume a rheostat wiring configuration means that the potentiometer doesn't make any changes when the knob is turned right? Not really sure what a rheostat is...haha

Do I HAVE to put the metal plate on? What difference does it really make if I leave the adhesive intact as opposed to attaching the metal plate onto the bottom?
Back to top
View user's profile Send private message
elmegil



Joined: Mar 20, 2012
Posts: 1516
Location: Chicago
Audio files: 14

PostPosted: Sat Mar 30, 2013 8:46 pm    Post subject: Reply with quote  Mark this post and the followings unread

No, a rheostat is a variable resistance. It's where you really only have one side and the wiper connected into the circuit, although commonly the other side will be tied to the wiper too.

Whereas a voltage divider doesn't actually change any resistance of importance to the circuit, but where the wiper lies determines the voltage at the wiper.

No, I wouldn't say you have to attach the plate. The smaller ones I have don't have plates and are none the worse for it.
Back to top
View user's profile Send private message
chieffrancis



Joined: Feb 07, 2013
Posts: 88
Location: california, united states

PostPosted: Fri Apr 05, 2013 5:33 pm    Post subject: Reply with quote  Mark this post and the followings unread

Question.

How do I put the "thermal contact" between the thermistor and whatever it's supposed be in contact with?

Do I just bend the thermistor in a way that the head is close/touching the other component?
Back to top
View user's profile Send private message
elmegil



Joined: Mar 20, 2012
Posts: 1516
Location: Chicago
Audio files: 14

PostPosted: Fri Apr 05, 2013 6:27 pm    Post subject: Reply with quote  Mark this post and the followings unread

Usually thermal grease or thermal glue is used. The grease is the stuff you'll see used in PCs to get good contact between the CPU and the cooling unit. Obviously to use the grease or glue you have to have it physically close as well.
Back to top
View user's profile Send private message
chieffrancis



Joined: Feb 07, 2013
Posts: 88
Location: california, united states

PostPosted: Sat Apr 06, 2013 1:27 am    Post subject: Reply with quote  Mark this post and the followings unread

Another question.

The arrow in all of the potentiometers (connected or not) all refer to the middle pin right?

Also, in some cases there is a "no symbol" nearby a trim pot, does anyone know what the "no symbol" is supposed to indicate?
Back to top
View user's profile Send private message
chieffrancis



Joined: Feb 07, 2013
Posts: 88
Location: california, united states

PostPosted: Sat Apr 06, 2013 1:29 am    Post subject: Reply with quote  Mark this post and the followings unread

elmegil wrote:
Usually thermal grease or thermal glue is used. The grease is the stuff you'll see used in PCs to get good contact between the CPU and the cooling unit. Obviously to use the grease or glue you have to have it physically close as well.


Does that mean that I should be using thermal glue/grease to physically attach the thermistor to the junction or chip? If so, where on the junction or chip (maybe it doesn't matter as long as it's physically/thermally attached somewhere on the casing of the chip (plastic part))?
Back to top
View user's profile Send private message
elmegil



Joined: Mar 20, 2012
Posts: 1516
Location: Chicago
Audio files: 14

PostPosted: Sat Apr 06, 2013 6:31 am    Post subject: Reply with quote  Mark this post and the followings unread

Yes, to the junction or chip. Generally what I've seen is as close to "center of mass" as possible. On a chip, generally lay the tempco along the length of the chip if possible, for a matched transistor junction, across the top of the junction and parallel to it.
Back to top
View user's profile Send private message
chieffrancis



Joined: Feb 07, 2013
Posts: 88
Location: california, united states

PostPosted: Sun Apr 07, 2013 4:51 pm    Post subject: Reply with quote  Mark this post and the followings unread

chieffrancis wrote:
Another question.

The arrow in all of the potentiometers (connected or not) all refer to the middle pin right?

Also, in some cases there is a "no symbol" nearby a trim pot, does anyone know what the "no symbol" is supposed to indicate?


Any takers on this one? haha
Back to top
View user's profile Send private message
elmegil



Joined: Mar 20, 2012
Posts: 1516
Location: Chicago
Audio files: 14

PostPosted: Sun Apr 07, 2013 6:27 pm    Post subject: Reply with quote  Mark this post and the followings unread

I've always assumed it was supposed to look like the top of the trimmer on a multi-turn trim pot, which is a circle with a slot for your screwdriver.
Back to top
View user's profile Send private message
chieffrancis



Joined: Feb 07, 2013
Posts: 88
Location: california, united states

PostPosted: Fri Apr 19, 2013 10:45 am    Post subject: Reply with quote  Mark this post and the followings unread

So I'm inquiring about using he MAP40-3003 as the power supply and I found that the output of the device requires Molex connectors.

Can anyone shed some light on Molex connectors and how to easily supply the synth with power if the supply has Molex outputs? Can I just use the other end of the wires coming from the Molex head and connect them directly to power rails or to the pins requiring the +/-15 and +5V?

I've got about a month left and I need to start putting things together haha. The IKC is going to be worked on as well as solder work for the modules since I don't really have time to test these circuits anymore..haha

I wonder if the thermistors will ever come in too..

Thanks for all the help dudes.
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic Moderators: Scott Stites
Page 3 of 8 [178 Posts]
View unread posts
View new posts in the last week
Goto page: Previous 1, 2, 3, 4, 5, 6, 7, 8 Next
Mark the topic unread :: View previous topic :: View next topic
 Forum index » DIY Hardware and Software » Thomas Henry 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