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MIDIbox Hardware Platform, Analog IN Module

Note: the MBHP_AIN module is only used by MIOS8 based applications which are running on the MBHP_CORE module. For MIOS32 based applications, e.g. running on a MBHP_CORE_LPC17 module, please use MBHP_AINSER64!

The AIN module comes with 4051 multiplexers for analog signals, each multiplexer provides 8 inputs. Currently only the layout for an ainx4 module with 4 multiplexers (=32 inputs) can be found here, I will add some more variations in the future. A full featured MIDIbox64 with 64 pots or faders requires two of these modules.


PCB data, can be viewed, modified and converted with Eagle Light. The .pdf based schematic has been created with xcircuit. There are no special eagle schematics available, since components have been netlisted in the .brd file directly!
Module Schematic Layout Data Quick-view
MBHP_AINX4_V2 mbhp_ainx4.pdf mbhp_ainx4_v2.brd mbhp_ainx4.gif
Additional informations
File Size Description
mbhp_ainx4_orderlist.txt 1k Reichelt orderlist
mbhp_ainx4_64pots.pdf 16k How to connect 64 pots to the MIDIbox64 with 2 * AINX4
auaimbctg.pdf 11k Important reminder!

Available Ports

Following interfaces are provided by the ainx4 module:

Name No. of pins Description
J1, J2, J3, J4 8 Analog inputs of the 4051 multiplexers. Have to be connected with the sliders of pots/faders, or can also be used as CV input (0V/5V), see also the MIDIbox Extensions Page. All unused analog inputs have to be clamped to ground (Vss), otherwise your MIDIbox will send out a lot of random MIDI events!
J5 6 Interface to J5 of the core module. J5:Vs and J5:Vd are the power pins, J5:A0..J5:A3 are the analog outputs of the multiplexers.
If you leave out a 4051, clamp the appr. analog input (J5:A0, ... J5:A3) to ground in order to avoid random MIDI events.
J6 3 Interface to J6 of the core module. These are the address pins of the multiplexers which allow the MIDIbox to select one of eigth inputs, the appr. signal will be routed to the output of the 4051. Connection matrix:
The other two pins of J6 of the core module (J6:Vd and J6:Vs) don't have to be connected with the AINX4 module.
J7 2 Power supply pins for the pots/faders.

Used Components

Here a list of the used components. A complete orderlist for Reichelt can be found here, Mouser partlist for the US: see SmashTV's Website, if you have a orderlist for a distributor on your country, feel free publish it on this page!

Part Name Value Description
IC1, IC2, IC3, IC4 4051 The analog multiplexers
C1-C4 100nF The additional bypass caps have to be placed on the bottom side of the PCB, as close to the +5V power input of the 4051 as possible.
J* * All connectors are optional, the cables can also be soldered directly into the board. Otherwise I suggest SIL headers (header sockets), known from PC motherboards. They are cheap and usefull.
DIL SOCKETS Don't forget to buy sockets for the 4051 multiplexers. 4 * 16 pin DIL sockets are required.

Soldering Guide

Start with soldering the 9 bridges which save you from creating a 2-layer board. You can use the cutted legs of caps and resistors, before you throw them away after you finished all the modules! :-)
Mount the sockets and connectors.
Note: analog experts suggest not to use sockets here, search in the web for the reasons. For beginners I strongly suggest the use of sockets!
4 additional bridges have to be connected via isolated cables between the analog outputs of the 4051 and J5
This picture shows how to connect two AINX4 modules together. The J6 plugs (address pins) have to be joined 1:1, same with the power supply pins of J5
Add also the four additional Bypass Caps between Vdd and ground of each chip on the bottom side of the PCB as close to the +5V power input of the 4051 as possible. They improve the power integrity. Since there isn't a ground rail near by the +5V input, I've used a so called "shrink hose" (german: Schrumpfschlauch) to isolate the cap leg which goes to ground.
Now add the connection cable to the core module. See also the MIDIbox64 Module Diagramm and mbhp_ainx4_64pots.pdf for further details.
Connection to the core module.
Two AINX4 modules connected with 64 pots (backside)
Two AINX4 modules connected with 64 pots (frontside). It's on you how to attach the modules on the chassis

Last update: 2024-05-08

Copyright 1998-2023, Thorsten Klose. All rights reserved.