# ADSR Input voltages **URL:** \ **Category:** Uncategorized\ **Created:** [January 31, 2023, 1:15pm UTC](https://lookmumnocomputer.discourse.group/t/adsr-input-voltages/5886 "2023-01-31T13:15:12Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![twinturbo](https://avatars.discourse-cdn.com/v4/letter/t/8baadc/32.png) [@twinturbo](https://lookmumnocomputer.discourse.group/u/twinturbo)\ **Post date:** [January 31, 2023, 1:15pm UTC](https://lookmumnocomputer.discourse.group/t/adsr-input-voltages/5886/1 "2023-01-31T13:15:12Z")
@jkb Trying to fathom the maths on the input controls on your ADSR. AS3310 needs 0- -5V on the CV ADR. and +5 on S I may just be stuipid. Output of the below network give 0-10.69V ![image](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/1/0/10350f82f9068b6fd828921bc7d082d122a2ad66.png) Out put of the OPAMP at 10.69V input ![image](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/c/3/c3833930af605b144816d0850b66597fefa927e3.png) trims to Give 0.18 to 1.997v ![image](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/a/7/a7e35b2ddbc87a41a09bc17696f33f3fc188226e.png) Output of this network gives 0.037v to 0.408v ![image](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/d/4/d4cef44d22d2c345f7de039efd33078060b6b821.png) Or am I missing something obvious, i would say it’s late but it’s midday.? Cheers Rob ---
**Author:** ![Jos](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/jos/32/151_2.png) [@Jos](https://lookmumnocomputer.discourse.group/u/Jos)\ **Post date:** [January 31, 2023, 4:21pm UTC](https://lookmumnocomputer.discourse.group/t/adsr-input-voltages/5886/2 "2023-01-31T16:21:02Z")
I would say your measurements and reasoning are correct. So … there must be something wrong with the schematic? ---
**Author:** ![jkb](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/jkb/32/26136_2.png) [@jkb](https://lookmumnocomputer.discourse.group/u/jkb)\ **Post date:** [January 31, 2023, 5:45pm UTC](https://lookmumnocomputer.discourse.group/t/adsr-input-voltages/5886/3 "2023-01-31T17:45:19Z")
In the datasheet there is a 10k/470R voltage divider when using 0 to -5V. This gives you something like -224mV for -5V. Datasheet states a minimum of -240mV. This can be adjusted by the trimpot. ---
**Author:** ![analogoutput](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/analogoutput/32/29663_2.png) [@analogoutput](https://lookmumnocomputer.discourse.group/u/analogoutput)\ **Post date:** [January 31, 2023, 6:12pm UTC](https://lookmumnocomputer.discourse.group/t/adsr-input-voltages/5886/4 "2023-01-31T18:12:00Z")
Presumably there doesn’t have to be a voltage divider on the input pin, just a voltage in the proper range and maybe a limiting resistor. So is there a reason not to just have the U1A amplifier gain 4x smaller and leave out R10? ---
**Author:** ![twinturbo](https://avatars.discourse-cdn.com/v4/letter/t/8baadc/32.png) [@twinturbo](https://lookmumnocomputer.discourse.group/u/twinturbo)\ **Post date:** [January 31, 2023, 6:35pm UTC](https://lookmumnocomputer.discourse.group/t/adsr-input-voltages/5886/5 "2023-01-31T18:35:55Z")
You know what, I asked this question a year or so ago, even re-read my own post/my own reply before posting this and did not realise my own answer to my own question. I think my repeat mistake is that it’s not 5V into the chip, it’s 5V into the voltage divider supply. the aparent control voltage at the IC is 0-240mv ---
**Author:** ![twinturbo](https://avatars.discourse-cdn.com/v4/letter/t/8baadc/32.png) [@twinturbo](https://lookmumnocomputer.discourse.group/u/twinturbo)\ **Post date:** [January 31, 2023, 6:38pm UTC](https://lookmumnocomputer.discourse.group/t/adsr-input-voltages/5886/6 "2023-01-31T18:38:29Z")
digging out that coat again… > [@AS3310 control voltages](https://lookmumnocomputer.discourse.group/t/as3310-control-voltages/2851/8): > > Cheers all makes sense now. Rob ---
**Author:** ![jkb](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/jkb/32/26136_2.png) [@jkb](https://lookmumnocomputer.discourse.group/u/jkb)\ **Post date:** [January 31, 2023, 7:53pm UTC](https://lookmumnocomputer.discourse.group/t/adsr-input-voltages/5886/7 "2023-01-31T19:53:19Z")
No, I don’t think so. I more or less copied it from the Crumar Stratus schematics. I guess there are a lot of ways to get the proper voltage range. ---
**Author:** ![twinturbo](https://avatars.discourse-cdn.com/v4/letter/t/8baadc/32.png) [@twinturbo](https://lookmumnocomputer.discourse.group/u/twinturbo)\ **Post date:** [January 31, 2023, 9:29pm UTC](https://lookmumnocomputer.discourse.group/t/adsr-input-voltages/5886/8 "2023-01-31T21:29:05Z")
I guess this is the rather ambiguous statement on the input voltage ![image](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/a/6/a6f3eb5d4f51d6cf65d405472f69a8efd479953d.png) And this all started with me thinking about the CV input. Which I hopefully calculated “R1” on the jack right to be around 27K9 ( so 27K + 1K ) ![image](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/e/4/e46312d1ea89548bc0214203c7736516abb9acda.png) ---
**Author:** ![craigyb](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/craigyb/32/21602_2.png) [@craigyb](https://lookmumnocomputer.discourse.group/u/craigyb)\ **Post date:** [February 1, 2023, 7:43am UTC](https://lookmumnocomputer.discourse.group/t/adsr-input-voltages/5886/9 "2023-02-01T07:43:46Z")
That’s what I don’t like about the AS3310/CEM3310, the control voltages are a nightmare to do. I always use Electric Druid EnvGen8c chips for EGs, 0-5v for all controls, you get a level CV too for velocity etc, they can be lin/log envs for compatibility and have a lopping function. Easily installed with a 1k resistor on pin 7 for timing and a 100nf across the power and your done. ---
**Author:** ![jkb](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/jkb/32/26136_2.png) [@jkb](https://lookmumnocomputer.discourse.group/u/jkb)\ **Post date:** [February 1, 2023, 7:51am UTC](https://lookmumnocomputer.discourse.group/t/adsr-input-voltages/5886/10 "2023-02-01T07:51:47Z")
Hmm, you need to make sure that you’re not getting below -240mA when adding both voltages. Or add the 12V to the socket switch when no jack is inserted. ---
**Author:** ![twinturbo](https://avatars.discourse-cdn.com/v4/letter/t/8baadc/32.png) [@twinturbo](https://lookmumnocomputer.discourse.group/u/twinturbo)\ **Post date:** [February 1, 2023, 8:09am UTC](https://lookmumnocomputer.discourse.group/t/adsr-input-voltages/5886/11 "2023-02-01T08:09:26Z")
Would adding 12V on the “Normal” jack not just saturate the input. May have to think about the envgen8, not set on using the 3310 to be honest. ---
**Author:** ![twinturbo](https://avatars.discourse-cdn.com/v4/letter/t/8baadc/32.png) [@twinturbo](https://lookmumnocomputer.discourse.group/u/twinturbo)\ **Post date:** [February 1, 2023, 8:14am UTC](https://lookmumnocomputer.discourse.group/t/adsr-input-voltages/5886/12 "2023-02-01T08:14:12Z")
Can’t seem to find a supply of 16f1764’s which is a shame as I would like to burn my own ☹ ---
**Author:** ![craigyb](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/craigyb/32/21602_2.png) [@craigyb](https://lookmumnocomputer.discourse.group/u/craigyb)\ **Post date:** [February 1, 2023, 9:19am UTC](https://lookmumnocomputer.discourse.group/t/adsr-input-voltages/5886/13 "2023-02-01T09:19:41Z")
Yeah, I have done both in the past, bought from ED and burnt my own when I realized I had a buggy version of the code, I bought a PIC programmer and reflashed all my stock to the 8C code to fix the looping bug. ---
**Author:** ![jkb](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/jkb/32/26136_2.png) [@jkb](https://lookmumnocomputer.discourse.group/u/jkb)\ **Post date:** [February 1, 2023, 9:59am UTC](https://lookmumnocomputer.discourse.group/t/adsr-input-voltages/5886/14 "2023-02-01T09:59:13Z")
Maybe you’re right. I guess it can be adjusted on the trimpot to not exceed -240mV. Update: perhaps add protection from negative voltage on CV input to not fry the chip?! I chose the 3310 because of its availability (also in the future). I also tried a discrete version but it was almost impossible to get a similar timing between voices. ---
**Author:** ![craigyb](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/craigyb/32/21602_2.png) [@craigyb](https://lookmumnocomputer.discourse.group/u/craigyb)\ **Post date:** [February 1, 2023, 11:50am UTC](https://lookmumnocomputer.discourse.group/t/adsr-input-voltages/5886/15 "2023-02-01T11:50:30Z")
There’s nothing intrinsically wrong with the AS3310 as an EG, but it just needs a lot of support chips to function. It’s around 40 years old, so nothing wrong with using a modern replacement that is more microprocessor friendly. I would also expect the envelopes to be identical as they are all using the same PIC chip. ---
**Author:** ![twinturbo](https://avatars.discourse-cdn.com/v4/letter/t/8baadc/32.png) [@twinturbo](https://lookmumnocomputer.discourse.group/u/twinturbo)\ **Post date:** [February 1, 2023, 12:31pm UTC](https://lookmumnocomputer.discourse.group/t/adsr-input-voltages/5886/16 "2023-02-01T12:31:37Z")
@craigyb Shame I can’t find the PIC , had same issue with the VCLFO… I bought a programmer but have no chips to use… Have secured an1847 to do a the Druid DCO though… @jkb Reverse protection hopefully? , and makes the resistor a nice 24K thanks to the voltage drop on the diode. ![image](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/9/f/9f540fd1c807c9c147c422b5ac913a8f55e0fbad.png) I may actualy bread baord this, don’t usualy… ---
**Author:** ![twinturbo](https://avatars.discourse-cdn.com/v4/letter/t/8baadc/32.png) [@twinturbo](https://lookmumnocomputer.discourse.group/u/twinturbo)\ **Post date:** [February 1, 2023, 1:16pm UTC](https://lookmumnocomputer.discourse.group/t/adsr-input-voltages/5886/17 "2023-02-01T13:16:26Z")
Actually found pics on DIGIKEY uk. So orderd a whole bunch!! may do two ADSR designs back to back 😉 ---
**Author:** ![twinturbo](https://avatars.discourse-cdn.com/v4/letter/t/8baadc/32.png) [@twinturbo](https://lookmumnocomputer.discourse.group/u/twinturbo)\ **Post date:** [February 1, 2023, 1:16pm UTC](https://lookmumnocomputer.discourse.group/t/adsr-input-voltages/5886/18 "2023-02-01T13:16:59Z")
got LFO and DCO compatible PICS too. ---
**Author:** ![analogoutput](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/analogoutput/32/29663_2.png) [@analogoutput](https://lookmumnocomputer.discourse.group/u/analogoutput)\ **Post date:** [February 1, 2023, 1:21pm UTC](https://lookmumnocomputer.discourse.group/t/adsr-input-voltages/5886/19 "2023-02-01T13:21:37Z")
Series diode will subtract 0.7 V off your CV and distort it below 0.7 V. A Schottky to ground placed after R1 will pass positive voltages unchanged; it allows negative voltages to -0.2 V but after the input stage gain and voltage division that’ll be minuscule. But do you need it at all? The datasheet says absolute maximum for control pins to ground is ±6 V. Or was @jkb talking about limiting the voltage at the pin to be above -240 mV? But my reading of the datasheet is that that is the limit of the range for good behavior, not for not frying the chip. ---
**Author:** ![jkb](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/jkb/32/26136_2.png) [@jkb](https://lookmumnocomputer.discourse.group/u/jkb)\ **Post date:** [February 1, 2023, 1:26pm UTC](https://lookmumnocomputer.discourse.group/t/adsr-input-voltages/5886/20 "2023-02-01T13:26:49Z")
> [@analogoutput](#): > > But do you need it at all? The datasheet says absolute maximum for control pins to ground is ±6 V. Ah, I missed that. Then it shouldn’t be a problem at all. [Next page](https://lookmumnocomputer.discourse.group/t/adsr-input-voltages/5886.md?page=2)