ADSR waveform generator

Preamble

Too rushed for an amusing title…

Here are a number of ADSR circuits, taken from the fantastic Yusynth website (which I came across after reading StackExchange – Building a synthesizer with no prior experience) – in particular the Archives page.

The circuits are described within PDFs, and I drew up the corresponding schematic and board files in EagleCAD.


The EagleCAD files available on github, although seeing as Micro$oft have just acquired Github, they may not be there for very long… Five minutes later – #movingtogitlab!

The EagleCAD files available on Gitlab: Testkins/ADSR-Waveform-generator

See also

Three ADSR circuits

There is a fourth, from Yusyth – Elektor Synth:

but it uses a CEM3310

Original schematic#1

The schematic below is taken from Adjustable exponential generator colors synthesizer’s sound, which is necessary reading to understand the circuit.

ADSR waveform generator - Adjustable exponential generator colors synthesizer's sound
ADSR waveform generator – Adjustable exponential generator colors synthesizer’s sound

A dual rail power supply is needed, which could be problematic. Four ICs are used as well.

Original schematic#2

The schematic below is taken from Two chip generator shapes sound, which is necessary reading to understand the circuit.

ADSR waveform generator - Two chip generator shapes sound
ADSR waveform generator – Two chip generator shapes sound

This is the simplest circuit of the three, with only two ICs and a single rail +15V power supply.

Original schematic#3

The schematic below is taken from Get an ADSR waveform for a few components, which is necessary reading to understand the circuit.

ADSR waveform generator - Get an ADSR waveform for a few components
ADSR waveform generator – Get an ADSR waveform for a few components

Only one IC and two transistors, a relatively simple circuit, although a dual voltage (5/10V) power supply is required.

Tranny swap

BC212 and BC182 do not exist on EagleCAD

From Re: Transistor Equivelents. – Google Groups

BC547, BC557

From BC182 and BC212 Equivalent Transistor

I would use a 2N3904 NPN to replace the BC182, and a 2N3906 PNP to replace the BC212

or

The 2SA1015 is the complement of the 2SC1815.

http://pdf1.alldatasheet.com/datasheet-pdf/view/29936/TOSHIBA/2SA1015.html

And the connections are also reversed.

From Equivalents for BC132, BC182, BC212

BC182 > BC174, BC190, BC546
BC212 > BC256, BC266, BC556

EagleCAD files

CEM3310

ADSR waveform generator - CEM3310
ADSR waveform generator – CEM3310

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