Author |
Message |
gabbagabi
Joined: Nov 29, 2008 Posts: 651 Location: Berlin by n8
Audio files: 23
|
Posted: Sat Mar 12, 2016 11:09 am Post subject:
ADSR Subject description: garden variety components |
|
|
This is the Basic ADSR circuit i drew up.
The circuit is heavily influenced by the Nicolas-ADSR and the YUSYNTH-ADSR .
I was always attracted by the simplicity of the Nicolas ADSR but the sustain Part I found always a bit imperfect.
Additionally I am obsessed with realizing all circuits only with Resistor values of 1k, 100k, and 1M, Transistor free when possible.
And then as I saw the Sustain MOD of the YUSYNTH ADSR --> bingo.
The Idea is a bit older so I developed some variations over the time, I will put them in the next posts.
Circuit is tested with 15V Supply Voltage.
The circuit works very well with one exeption: you will always find a more or less little offset voltage on the output, during the tests I measured between 0,2V and 0,5V! (It may can be avoided if you use a FET instead the PNP Transistor??? But I haven’t it tested yet.)
EDIT: i think not using a poa-cap is the solution
A little about the circuit:
The Gate Trigger Level is at about 0,6V (the Voltage Drop of D2), it is designed like that because no change is needed when you change the supply voltage.
The Value of C1 is not so critical. I have tested on the Breadboard values between some hundred pF and 10nf.
The Amplitude of the Envelope is determinate by R4 and R5, when both are equal the Amplitude will be about 0,5x Supply Voltage. Choose the values according to your needs, especially if you change the supply voltage.
Choose the A-D and R Pots and C2 according to your needs.
The Value of the S-Pot itself is not critical, but the value of the pot and R6 has to corespondend to the propotion of R4/R5.
The opamp is lm324 because it is quite robust and can work on single supply.
Description: |
|
Filesize: |
60.02 KB |
Viewed: |
808 Time(s) |
This image has been reduced to fit the page. Click on it to enlarge. |
|
Last edited by gabbagabi on Sun Aug 13, 2017 8:55 am; edited 2 times in total |
|
Back to top
|
|
|
gabbagabi
Joined: Nov 29, 2008 Posts: 651 Location: Berlin by n8
Audio files: 23
|
Posted: Sat Mar 12, 2016 11:22 am Post subject:
|
|
|
The basic circuit @9V in the Simulation connected as "Two-knob-only" and Transistor free ADSR
My ugly prototype of this @15V
and a Scope-Shoot as evidence --> u can see the described offset
Description: |
|
Filesize: |
905.02 KB |
Viewed: |
338 Time(s) |
This image has been reduced to fit the page. Click on it to enlarge. |
|
Description: |
|
Filesize: |
733.49 KB |
Viewed: |
307 Time(s) |
This image has been reduced to fit the page. Click on it to enlarge. |
|
Description: |
|
Filesize: |
42.25 KB |
Viewed: |
386 Time(s) |
This image has been reduced to fit the page. Click on it to enlarge. |
|
Last edited by gabbagabi on Sat Mar 12, 2016 11:55 am; edited 1 time in total |
|
Back to top
|
|
|
gabbagabi
Joined: Nov 29, 2008 Posts: 651 Location: Berlin by n8
Audio files: 23
|
|
Back to top
|
|
|
gabbagabi
Joined: Nov 29, 2008 Posts: 651 Location: Berlin by n8
Audio files: 23
|
|
Back to top
|
|
|
gabbagabi
Joined: Nov 29, 2008 Posts: 651 Location: Berlin by n8
Audio files: 23
|
|
Back to top
|
|
|
nicolas3141
Joined: May 25, 2007 Posts: 185 Location: Christchurch, New Zealand
|
Posted: Sat Apr 16, 2016 4:35 am Post subject:
|
|
|
Great to see some interesting ideas. I find it fascinating that it is still possible to come up with new options for an ADSR after all these years, and without needing to resort to any components beyond the common or garden varieties.
Nicolas |
|
Back to top
|
|
|
gabbagabi
Joined: Nov 29, 2008 Posts: 651 Location: Berlin by n8
Audio files: 23
|
Posted: Mon Apr 25, 2016 3:14 am Post subject:
|
|
|
Hey nicolas,
good to see you are still around after all those years
And many thanks, now i have a name for my desire - the garden variety component desire.
In german we call them forest and meadow components
May you wouldt have a look to garden variety component filters? http://electro-music.com/forum/topic-66911.html
cheers bb
gabbagabi |
|
Back to top
|
|
|
Pantheon
Joined: Feb 17, 2011 Posts: 36 Location: Edinburgh
|
|
Back to top
|
|
|
Grumble
Joined: Nov 23, 2015 Posts: 1294 Location: Netherlands
Audio files: 30
|
Posted: Sat May 14, 2016 12:34 am Post subject:
|
|
|
yes, there is something wrong.
the connection R1*R2 should be before C1, or else you will not get a sustain level of the same width as the gate.
but by doing that, remember to place a high value resistor between C1*+In U1 and ground or else, depending on the type of opamp, the cap C1 might charge from the bias current of +In U1 effectively locking up U1 |
|
Back to top
|
|
|
gabbagabi
Joined: Nov 29, 2008 Posts: 651 Location: Berlin by n8
Audio files: 23
|
|
Back to top
|
|
|
Grumble
Joined: Nov 23, 2015 Posts: 1294 Location: Netherlands
Audio files: 30
|
Posted: Sun May 15, 2016 4:07 am Post subject:
|
|
|
please tell me the settings of the scope? my guess is 0.2 sec/div but it is already vivible that the sustain voltage is dropping.
try a gate time of several seconds long and look again. |
|
Back to top
|
|
|
gabbagabi
Joined: Nov 29, 2008 Posts: 651 Location: Berlin by n8
Audio files: 23
|
|
Back to top
|
|
|
Grumble
Joined: Nov 23, 2015 Posts: 1294 Location: Netherlands
Audio files: 30
|
Posted: Mon May 16, 2016 3:22 pm Post subject:
|
|
|
I'm sorry, just noticed that U2 is a Schmittrigger |
|
Back to top
|
|
|
nicolas3141
Joined: May 25, 2007 Posts: 185 Location: Christchurch, New Zealand
|
Posted: Tue May 17, 2016 1:04 am Post subject:
|
|
|
The reason you need a dual supply for this type of ADSR is that the PNP needs a negative voltage on its base (at least -0.7V negative) in order to fully drain the cap during the Release phase when the gate goes low.
Another thing to watch out for with this is that some PNP transistors will behave badly if the base goes all the way to -15V, hence some variations on this ADSR arrangement have an extra resistor to prevent it going too negative during the gate-off phase.
And another thing to watch for is the current capabilities of your opamp when operating near the limits. The LM324 when on a single sided supply can put its output down to ground only if the current it is required to sink is really tiny, like microamps. A lot of opamps are like this, they can swing their outputs near the rails, or they can handle milliamps of current, but not both those things at the same time.
Nicolas |
|
Back to top
|
|
|
gabbagabi
Joined: Nov 29, 2008 Posts: 651 Location: Berlin by n8
Audio files: 23
|
Posted: Tue May 17, 2016 9:39 am Post subject:
|
|
|
thx nicolas,
sometimes is the obvious so obvious that you cant see it.
For the moment i will leave it like it is, the single supply version has an offset the dual supply version not.
Do you know for what i have to look for in the datasheet to check the opamp current sink capabilities, eg TL0x4 which i use regularly?
@grumble, no problem ur welcome
cheers bb
gabbagabi |
|
Back to top
|
|
|
vandelay
Joined: Apr 01, 2016 Posts: 1 Location: USA
|
Posted: Tue May 17, 2016 4:43 pm Post subject:
|
|
|
I'm watching with great interest, as I am on the hunt for a single supply (12V) ADSR. Good luck and thanks for sharing your work! |
|
Back to top
|
|
|
nicolas3141
Joined: May 25, 2007 Posts: 185 Location: Christchurch, New Zealand
|
Posted: Wed May 18, 2016 2:40 am Post subject:
|
|
|
To run this ADSR on a single supply without major modification to the circuit I would use a couple of resistors and an extra opamp to create a virtual ground. If you are building a module which will have its own battery then that is job done. If the ADSR has to share its power supply with other modules then you will need to add a level shifter to remove that offset. Give me a minute and I will try to draw it. |
|
Back to top
|
|
|
nicolas3141
Joined: May 25, 2007 Posts: 185 Location: Christchurch, New Zealand
|
|
Back to top
|
|
|
nicolas3141
Joined: May 25, 2007 Posts: 185 Location: Christchurch, New Zealand
|
|
Back to top
|
|
|
gabbagabi
Joined: Nov 29, 2008 Posts: 651 Location: Berlin by n8
Audio files: 23
|
Posted: Fri May 20, 2016 10:41 am Post subject:
|
|
|
thx nicolas for the input,
looks interessting, but iam not so into virtual ground technics,
so iam working on a (more basic) solution by replacing the PNP with a double NPN.
the offset by now is a little noise @20mV, not bad i have guessed. But then i hooked this up to my thruZeroVco together with a LFO --> a regular auto triggering has happend. Maybe a voltage can sneak to the negative input of the triggerOPA via the direct connection to the output.
test next week
cheers bb
gabbagabi |
|
Back to top
|
|
|
nicolas3141
Joined: May 25, 2007 Posts: 185 Location: Christchurch, New Zealand
|
Posted: Sat May 21, 2016 3:59 am Post subject:
|
|
|
Yes, the NPN solution should work well. Let us know what configuration works best.
But the sensitivity to false triggering is also a problem that comes from not having the ability to go below zero. Without that bias or virtual ground (or a dual supply) then the switch points for the main schmitt trigger are zero volts and roughly half of V+. In order to provide some immunity to noise the lower switch point really needs to be a bit below zero, but you can't get that without a dual supply or a virtual ground or something equivalent.
I guess it sort of depends where you are coming from. For those who are coming from a background of audio and discrete transistors then bias voltages are just the normal way everything works and in the opamp world virtual ground is just a different name for the same thing.
Nicolas |
|
Back to top
|
|
|
gabbagabi
Joined: Nov 29, 2008 Posts: 651 Location: Berlin by n8
Audio files: 23
|
Posted: Thu May 26, 2016 1:10 pm Post subject:
|
|
|
after a hard week, i burned the last opa and broke my glasses, i had the (hopefully) problem-solving-idea under the shower (no joke) for the single supply adsr. No more autotriggering observed.
I observed one nice strange behavior, there is a spike before the release if u set the attack to zero (right scope), if u set attack a little bit over zero the spike will disappear (left scope), it is a unique feature-bug i like to keep it
the offset is down to 20mV (ch2 scope left, both channels meassuring same point),
Description: |
|
Filesize: |
64.96 KB |
Viewed: |
217 Time(s) |
This image has been reduced to fit the page. Click on it to enlarge. |
|
Description: |
|
Filesize: |
114.68 KB |
Viewed: |
270 Time(s) |
This image has been reduced to fit the page. Click on it to enlarge. |
|
|
|
Back to top
|
|
|
gabbagabi
Joined: Nov 29, 2008 Posts: 651 Location: Berlin by n8
Audio files: 23
|
|
Back to top
|
|
|
belltones
Joined: Aug 08, 2017 Posts: 12 Location: Philadelphia
|
Posted: Thu Aug 31, 2017 2:49 pm Post subject:
|
|
|
i'm diggin on these minimal module designs you're posting, sometimes I feel like it's diminishing returns with people's more complex designs! i like the idea of building a whole synth on a 4x4" perf. that would be true genius. |
|
Back to top
|
|
|
AlanP
Joined: Mar 11, 2014 Posts: 746 Location: New Zealand
Audio files: 41
|
Posted: Thu Aug 31, 2017 3:39 pm Post subject:
|
|
|
I'm quietly looking forward to gabbi's freq shifter, those usually use a monstrous amount of components. So his version should be very cunning! |
|
Back to top
|
|
|
|