AS3310 control voltages

The dataSheet for the AS3310 envelope generator seems to indicate the control voltages for

A D R are 0 to -5V
S is 0 to 5V

AS3310 ADSR Voltage Controlled Envelope Generator (

@EddyBergman 's strip board mirrors the Data sheet.

ADSR+Datasheet+AS3310.jpg (1600×984) (

I can’t work out how the input voltage is limited to this ±5V scale…

The sustain seems to be 0-15V

And the ADR I can’t fathom either. How does it give 0 -5V ?



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I advise not to build that particular ADSR on my website. It was one of my first projects. The digisound ADSR uses the 3310 too and is much better. Or the 7555 ADSR also works very well.


Yeah, I was just curious to see how it worked and have the total basics. It acts as a chip testet…

But now curious about the control voltages, the digisound one is odd too unless I am missing something.

Odd in what way? …

perhaps I am just being thick.

The input control voltages on the 3310 are 0 to -5V

The fixed voltage divider is 10k/470ohms with an input of 0 to -15V ( in the original) …

Does that not give a maximum output of -0.673v??

As I read it they’re talking about 0 to -5 V into the 10k resistors.

In the Digisound design a 0 to +15 V CV from the knob is divided down by 62k/150k to 6.2 V on the 10k resistor.

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I will get my coat, yes of course it’s 5V before the divider.


Cheers all makes sense now.


0 to −6.2 V, right? (it’s an inverting amplifier)

yes, +15 inverted to 0 to -6.2ish :wink:

The inverting OP Amp seems like overkill??

Is there any reason a 7905 would not be used to provide the voltage reference?


You’re transforming 0 – +15 V control voltages into 0 – -6.2 V as the chip needs.

Which opamp is that? IC2a in @analogoutput’s post is a summing amplifier, mapping the sum of the positive control voltages (0−15 V from the pot, 0−10 V from the inputs) to a negative voltage. If you don’t need an external input, you could use a negative reference with the pot instead (with −12 V or −15 V supplies the easiest way to do that is to add a resistor in series with the potentiometer).

Good point, my mind is over complicating things.

So waking up this morning.

Are the values 10K/470 correct for an input voltage of -15V , I see other diagrams with the




15v 62000/1000 = .238v

15v 10000/470 = 0.673v
5v 10000/470 = .224v

Seems to me (unless I am mad) that using the values from the data sheet with a 15V rail will limit the useable range of the POT.

Have substituted the resistors for 62k/1.2k on (ADR)
Have added an 7805 to supply the sustain…

Seems better range of control now.