Monday, 29 October 2018

LZX - Cadet DIY build - Processor VII

Some pics of the Cadet DIY modular video synth build.
I am an independent builder and have nothing to do with LZX industries.
These aren't official build notes, just my records to help me trouble shoot.
It's a work in progress.
Do let me know if you spot any errors or omissions.
This is module no.7 (Processor VII).
It's a simple wide bandwidth voltage processor and 2 channel mixer 
The format is Eurorack.

I'm guessing that this is based around the old LZX triple video processor and the new Passage module.


The Passage and TVP have 3 channels & are suitable for mixing lots of signals... like video, audio & low frequencies.
So it's probably a good idea to build a few processors if you'd like to have something approaching their processing power.

 I used a standard DPDT on - on switch .

a 3rd build with different caps and jacks.


ALMOST there







ICs etc used in this project:
LM6172IN/NOPB
TL431BQLPR
TL074CN

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Sunday, 28 October 2018

LZX Cadet - Fader VI - DIY - video synth

Some pics of my LZX Cadet fader build.
It's a 2-input, 1-output voltage controlled crossfader module.
This is the 6th eurorack module in the series to build a video synthesizer.

I am an independent builder and have nothing to do with LZX industries.
These aren't official build notes, just my records to help me trouble shoot.
It's a work in progress.
Do let me know if you spot any errors or omissions.
The module is possibly based around the old LZX triple video fader & Key Generator module (TVF & kg).
The TVF & kg  has 3 voltage controlled faders & 3 comparators (Key Generators)

R13, R15 - DNP - do not place

This video amp ic is out of stock at mouser.
584-LT1251CN#PBF
LT1251CN#PBF 

I'm using this instead:
584-LT1256CN#PBF
LT1256CN#PBF 


It's the core component. Very useful. You will also find it used in the Cadet X Multiplier module 
 

I reckon you should build a few of these faders.



iT'S done.

ICs etc used in this project:
TL072IP
LT1251CN#PBF
LM6172IN/NOPB
TL431BQLPR

Patches:
If you patch the squarewave and triangle wave into a Fader module (CV in and ch1 in, you get a Sawtooth wave too. (only half though)

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LZX - Scaler - Cadet V - DIY build


Some pics of my LZX Cadet scaler build.
This is the 5th module in the series.
I am an independent builder and have nothing to do with LZX industries.
These aren't official build notes, just my records to help me trouble shoot.
It's a work in progress.
Do let me know if you spot any errors or omissions.

This is an interface module to enable you to use 3rd party modules (eg eurorack) with the LZX system.

The module can be built to convert 5V to 1V, 1V to 5V, +/-5V to 1V or 1V to +/-5V. I
It's based around the LZX bridge module


R7, R8, R9, R10, R11, R13, R25, R27, R29, R30, R31 --- DNP --- Do Not Place
U3 & U4 - DNP
C5 & C9 - DNP

The jacks with a line around them are inputs.
The white circle jacks are outputs.
This version will convert 5V to 1V.



 The PCB looks like this when finished:


IC's used in this build:
LM6172IN/NOPB (x2)

Links:
LZX help - scaler vs multiplier


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Saturday, 20 October 2018

Vectrex & LZX video synth - Curliing effects

I was trying to achieve vector rescanning on the vectrex but instead got some rather
interesting  though unexpected "curling" effects.

Has anyone does something similar ?

some pics of the LZX setup.

tHE image on the vectrex was really small initially, but with amplification i was able to fill about 2/3 of the screen

I connected a horizontal ramp to the X input, a vertical ramp to Y and the composite output to the Z. 
Maybe I should use a luma output ?
 
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LZX - Cadet IV - Ramp generator

This is the fourth module in the series of LZX's Cadet DIY synthesizer.
Many thanks to Liz for making this possible.
A ramp generator is a signal generator which generates a ramp waveform.

It's actually a dual ramp generator which "creates 3 different fixed frequency ramp waveforms locked to the horizontal and vertical dimensions of a video display".
That 14 pin input header in the pic below is where the horizontal & vertical sync signals enter the module.
Modules with 14-Pin Sync Outputs include Visual Cortex, Video Sync Generator and Cadet I Sync Generator.

This will be essential if I want to do some vector rescanning.


The LM6172 op amp
This is used a lot in the cadet series. Get lots of these !!!

 The TL431 - buy this in bulk too.



ICs (and other impt components) used in this build:
LM6172IN/NOPB  (x2) ...this is a dual op amp... specified at ±5V power supply for low
                                 voltage applications such as portable video systems.
TL431BQLPR (x3).... Adjustable Precision Shunt Regulator
                               TL431 shunt regulator circuit explained 
TL072IP - standard op amp
SN74HC14N- - it's a hex schmitt trigger
TL074CN (x2) .....standard op amp
BS170 N-Channel...MOSFET...metal-oxide semiconductor field-effect transistor.
           used for switching or amplifying signals.


The SN74HC14n .... its also used in the Cadet IX VCO  though I don't think its responsible for the waveform generation in this circuit (please correct me if I'm wrong).

I think the ramp generators are built using mostly transistors.(2N3906/BS170)
For this to work, the voltage must be very precise... thus the use of the TL431.
This waveform increases steadly as the capacitor charges until it hits its peak and then decreases suddenly as the capacitor discharges.
Since this waveform repeats over and over again, this waveform generator appears as an oscillator.

iT'S DONE !!!
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Links:
LZX official
Muffs - Cadet series DIY/assembled
All about ramp generators
Youtube  Ramp Generator Circuit built with Transistors

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Friday, 19 October 2018

Rutt-Etra - Vector Rescanning - the perfect monitor?

A bit about vector rescanning 

I've been trying to accomplish vector rescanning for years.
Never really successfully.
Part of the problem I think has been my early confusion & lack of understanding of the different types of oscilloscopes, vectorscopes & waveform monitors (and I'm still learning).

Living in Australia, doesn't make it easier to find old working scopes from the 70's and 80's and attempts of posting them from the USA usually ends in tears. Postmen seem to love throwing delicate analog instruments around in their truck. I lost 3 scopes this way.
Two that have survived the rigours of FedEx & Australia post are the Tektronix T922 and 465B
Lovely scopes that I use all the time for standard audio waveform measurements .... but not 100% successful for Rutt-Etra stuff.

 Tektronix T922
 Tektronix T922 rear with z axis input.

 Tektronix 465B

The two models that often come up in the various forums as working well for vector rescanning are the
Leader LBO 51MAC, and the Tektronix 620 .
(Unconfirmed ... Leader LBO-514A & Tektronix 608)
Leader LBO-51MA

Tektronix 620 is on the left.
I just purchased this on ebay. It hasn't arrived yet, & I'm waiting with anticipation to see if it survives the trip.

And of course, there is the vectrex.

My understanding is that the vectrex isn't prefect for vector rescanning as it does not have the bandwidth ....but it kinda works in limited ways
It is better suited for lower frequency oscillographics.  

However, if you still want to do vector rescanning you need:
1.Video Input to extract luma from your video source
2. H & V ramps generator .

Thus if you are using Cadet modules you only need one Ramps, a Sync Gen and an Input. 
A LZX visual cortex (VC) has all of this.
Connect the horizontal ramp to the X, the vertical ramp to Y and the luma output (of the VC or the VideoInput) to the Z. 



The Rutt/Etra Video Synthesizer is an analog raster manipulation device built in 1972 for image processing and real-time animation. The Rutt/Etra was co-invented by Steve Rutt and Bill Etra

 
Links
+ Muffs- vector modification
+ Vectrex Hackaday
+ Hacking a vectrex - Lumpybanger
+ Zektor - using the vectrex monitor
+ Muffs - vector rescanning for dummies
+ Muffs - good oscilloscope for vector rescanning
+ Rutt-cadetra blog 
+ Rutt/Etra Video Synthesizer Demo (1974) youtube
+ Rutt-Etra-izer

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Egypt - The Step Pyramid

This was one of the earlier attempts The Egyptians had at pyramid building.
You can visit it in the Saqqara necropolis, Egypt, northwest of the city of Memphis.

The Step Pyrmid was built ca. 27th century BC during the third dynasty for the burial of Pharaoh Djoser by his vizier, Imhotep. Imhotep was a brilliant architect.

The design was a revolution. It started off as a standard mastaba tomb — a flat-roofed rectangular monument with sloping sides  made of dried clay brick. These usually covered underground passages where the deceased was entombed.

For reasons we don't know,  Imhotep decided to expand the original structure by stacking mastabas (each smaller than the last) on top of each other. This evolved into a 197-foot-high (60 meters) pyramid, with six layers.

 It is estimated that there is 11.6 million cubic feet (330,400 cubic meters) of stone and clay.

























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