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aout_4

AOUT_4 module

Using the MAX525 DAC gives nice CVs. The circuit is designed with an improved output buffer. It's possible to switch the gain and and offset for different CV ranges.

Schematic

The DAC portion is essentially the same as the original version:

The gates were omitted. Normally RC1 can be used for two cascaded DACs.

The AOUTs each go through a buffer:

This is a dual inverting-opamp design. The first adjusts the scale of the CV. The second has extra mixer resistors to inject other CVs, such as a fixed offset and/or fine-tune control.


BOM v1.1

Part Value Package Description
C1 10u E2,5-6 POLARIZED Cap
C2 100n C025-025×050 CAPACITOR
C3 10u E2,5-6 POLARIZED Cap
C4 100n C025-025×050 CAPACITOR
C5 100n C025-025×050 CAPACITOR
C6 100n C025-025×050 CAPACITOR
C7 100n C025-025×050 CAPACITOR
C8 100n C025-025×050 CAPACITOR
C9 10u E2,5-6 POLARIZED CAP
C10 100n C025-025×050 CAPACITOR
C11 10n C025-025×050 CAPACITOR
C12 10p C025-025×050 CAPACITOR
C13 10p C025-025×050 CAPACITOR
C14 10p C025-025×050 CAPACITOR
C15 10p C025-025×050 CAPACITOR
C16 10p C025-025×050 CAPACITOR
C17 10p C025-025×050 CAPACITOR
C18 10p C025-025×050 CAPACITOR
C19 10p C025-025×050 CAPACITOR
C20 10n C025-025×050 CAPACITOR
C21 10u E2,5-6 POLARIZED
C22 100n C025-025×050 CAPACITOR
IC1 TL074P DIL14 OPAMP
IC2 TL074P DIL14 OPAMP
IC3 MAX525 DIL20_SML DAC
IC4 MAX6007* LM4041A12DBZ Vref
J1 PINHD-2X54WALL PINHEADER
J2 PINHD-2X54WALL PINHEADER
J3 PINHD-2X54WALL PINHEADER
JP1 PINHD-1X2SMALL PINHEADER
JP2 PINHD-1X2SMALL PINHEADER
JP3 PINHD-1X2SMALL PINHEADER
JP6 PINHD-1X2SMALL PINHEADER
JP7 PINHD-1X2SMALL PINHEADER
JP8 PINHD-1X2SMALL PINHEADER
JP9 PINHD-1X2SMALL PINHEADER
JP10 PINHD-1X3SMALL PINHEADER
JP11 PINHD-1X3SMALL PINHEADER
JP12 PINHD-1X3SMALL PINHEADER
JP13 PINHD-1X3SMALL PINHEADER
JP14 PINHD-1X3SMALL PINHEADER
JP15 PINHD-1X3SMALL PINHEADER
JP16 PINHD-1X3SMALL PINHEADER
JP17 PINHD-1X3SMALL PINHEADER
L1 BEAD 5MM INDUCTOR
L2 BEAD 5MM INDUCTOR
R1 1k 0204/7 RESISTOR
R3 1k 0204/7 RESISTOR
R10 220R 0204/7 RESISTOR
R11 50k 0204/7 RESISTOR
R12 50k 0204/7 RESISTOR
R13 50k 0204/7 RESISTOR
R14 50k 0204/7 RESISTOR
R15 130k 0207/2V RESISTOR
R16 100k 0204/7 RESISTOR
R17 50k 0204/7 RESISTOR
R18 50k 0204/7 RESISTOR
R19 50k B64Y trim pot
R20 220R 0204/7 RESISTOR
R21 50k 0204/12_ANDY RESISTOR
R22 50k 0204/9_ANDY RESISTOR
R23 50k 0204/7 RESISTOR
R24 50k 0204/7 RESISTOR
R25 130k 0207/2V RESISTOR
R26 100k 0204/7 RESISTOR
R27 50k 0204/12_ANDY RESISTOR
R28 50k 0204/7 RESISTOR
R29 50k B64Y trim pot
R30 220R 0204/7 RESISTOR
R31 50k 0204/9_ANDY RESISTOR
R32 50k 0204/9_ANDY RESISTOR
R33 50k 0204/7 RESISTOR
R34 50k 0204/7 RESISTOR
R35 130k 0207/2V RESISTOR
R36 100k 0207/2V RESISTOR
R37 50k 0204/7 RESISTOR
R38 50k 0204/7 RESISTOR
R39 50k B64Y trim pot
R40 220R 0204/7 RESISTOR
R41 50k 0204/12_ANDY RESISTOR
R42 50k 0204/7 RESISTOR
R43 50k 0204/7 RESISTOR
R44 50k 0204/7 RESISTOR
R45 130k 0204/7 RESISTOR
R46 100k 0204/7 RESISTOR
R47 50k 0204/7 RESISTOR
R48 50k 0204/7 RESISTOR
R49 50k B64Y trim pot
RC1_RC2SJ2W Jumper (normally as RC1)
VR1 VOLTAGE reg (optional)

Versions

v1.1: first release.

Assembly

The clearance with the common 3296 series trimpots is quite tight! Although everything does fit, you may wish to place the trimpots in before the surrounding resistors. The resistors could even go on the back of the board, as long as you don't melt the trimmer housings too much. There are smaller trimmers available, but they seem to be quite pricey.

The 50k value for most resistors is not too important. 47k will work fine.

For best results, get 0.1% resistors or hand-match R11/13/14/17/18, R21/23/24/27/28 and so on.

Headers and jumpers

J1 is a normal Eurorack-style power header. Stripe = -12V J2 matches a Core J19 header. RC1/RC2 solder jumper: connect only one (RC1 normally) to the centre pad J3 can cascade additional modules. Two can use the same latch (RC1 or RC2).

JP1 is intended as a connector to other boards or for SIP connectors pin order from the part designator: 0V|3v3|0V|-12V|0V|+12V

JP14/15/16/17: the square pin can be connected to an offset voltage for fine tuning. This will need some reference to the +/-12V rails.

JP6/7/8/9:


Interconnection to Core

As noted above.


License

Currently the design is © 2018 antilog devices with all rights reserved; all documentation is CC BY-NC-SA 3.0.

aout_4.txt · Last modified: 2018/03/10 11:42 by latigid_on