LZX Castle Video Synthesizer - 000 ADC

Some build pics of the first module in the Castle series.

This module is in Eurorack format.
iT'S 4HP and all through hole.
Quite an easy build

I must thank the entire team from LZX  and Philip Baljeu for making this DIY system possible.
Building these modules from scratch is a great way to learn.

 tHESE are not official build pics and I am in no way affiliated with LZX.

 The Castle 000 ADC is an Analog to Digital Converter. It's used to change an analog input signal in to a 3-Bit data stream.  You will see on the module a single input on the top and 3 outputs below, labelled D0, D1, D2.

"The ADC will take an analog signal and split it into 3 bits or zones, the separate outputs kind of look like a square wave version of staircase, the first output D0 has 4 lines, d1 has 2, and D2 has 1".
 (facebook post from Philip)

The main IC is the SN74HC148N. 
The SN74HC148  features priority decoding of the  inputs  to  ensure  that  only  the  highest-order data
line is encoded. These devices encode eight data   lines   to   3-line   (4-2-1)   binary   (octal).

The SN74HC148 features ‘priority encoding’ where, if more than one input is active at the same time, the output will select only the most significant active input.

The internal logic is shown below:

The voltage regulators

tHIS is the underside of the voltage regulators. Be careful not to short circuit.

 tHERE  are six LM6172s

Finally done.

Troubleshooting:
There appears to be a sweet spot when adjusting the Bias & Gain knobs.
I'm not sure if this is normal behavior. Outside this narrow range the output signal disappears.
The schematics indicate that the Bias/gain 10K pots effect the first 6172 op amp.

Possibly tweaking the value of those 10k pots or the associated resistors might give a better outcome ??????
I received an email from my friend, Chris who directed me to some info regarding this:

"The bias range is pretty wide, maybe too wide. I wanted enough range to mess with many signals, not just 1V. The controls aren't really something I see people changing a lot, more of just to get the settings right in to the ADC and set and forget. But if people think the range is unusable I can look in to limiting it. In the meantime, anyone who wants to try for themselves, R10 would be the thing to change. its 4.99K right now.” (Philip B).

The Gain control on the ADC goes from non-inverted on the left through zero to inverted on the right. 

LZX - Castle
Introduction
00_000 ADC - Analog to digital converter
01_001 DAC - Digital to Analog converter
02_010 Clock VCO
03_011 Shift Register
04_100 Multi Gate
05_101 Quad Gate
06_110 Counter
07_111 Flip flops

Links
+ ADC overview - LZX
+ LZX industries 
+ Bit numbering
+ CMOS
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