Wednesday, 24 May 2017

1050 Mixer sequencer - Build notes

This is a Eurorack module inspired by the ARP 2500 mix sequencer.

There are lots of SMD components so it's probably not a good one for beginners.

Here are Andrew's build notes:

Muffs notes:

Some pics of the virgin PCB & Panel

Some NLC words of wisdom

This is great SMD soldering practice.
I like to get those ICs on first. These are SOIC.
The sequencer section uses one CD 4017 (decade counter) , three CD4071s (quad 2-input OR gate) and  one CD 4081 (CMOS Quad 2-input AND gate).

The 4017 decade counter is central to this sequencer.
Sending a pulse to the clock input (pin 14) sends a pulse out from each of the outputs in sequence.

A bit about gates.

CD4071 (quad 2-input OR gate)
 Truth table of the OR gate:

 CD 4081 (CMOS Quad 2-input AND gate).
This is the truth table for the AND gate
I'm using a DG 212.
Here are the mouser details.

You can also use a DG 442. Just make sure it can handle +/-12V.
My DG 212 can handle +/-15V so should be OK.
It's an analogue switch. 4x SPST.

Some earlier versions of the DG442 require a voltage offset on pin12, the spaces for these resistors are on the PCB marked 100k* and 120k*.
New versions do not require these resistors, so check the datasheet for your  IC, if pin 12 is marked ‘NC’ you do not have to install these resistors.

My DG 212 has pin 12 marked as VL. so I will install the resistors.
Data sheet.

Next install the rest of the SMDs.... lots of resistors & caps. These are 0805s
Parts marked "c" are 100K .

Then the through hole stuff.

Install jacks, switches first. Line up with panel.
Then pots. I used B100K.

Don't forget the ground wires for the jacks. I use left overs from caps & resistors.

The PCB looks like this:

Finally the LEDs

LED orientation : The long lead (anode) , (+) goes into the square hole on PCB.

Yah it works. Nice one Andrew.
You can find more NLC builds here.

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