Showing posts with label DIY. Show all posts
Showing posts with label DIY. Show all posts

Wednesday, 31 October 2018

LZX cadet VIII - Video Synth - Hard Key Generator

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 (Hard Key Generator VII).

It's a wideband voltage comparator with voltage controlled threshold level.
A voltage comparator is an electronic circuit that compares two input voltages and lets you know which of the two is greater.
The ICs used are:
TL072 - a pretty standard Op amp
TL431BQLPR  - Adjustable Precision Shunt Regulator
LM6172IN/NOPB - Operational Amplifier - Dual High Speed, Low Power
LM361N/NOPB - Analog Comparators Hi Speed Diff Cmptr



1stly, the power section - reverse voltage protection & 5V regulator






ICs etc used in this project
LM6172IN/NOPB
TL431BQLPR
TL072IP
LM361N/NOPB

 Mods:
+The C8 hard key circuit can be adapted to provide a pulse width modulation CV and output. Just send the triangle wave into the key input and threshold becomes pulse-width.

Links:
LZX official
Muffs - Cadet series DIY/assembled

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Click here to access the Video Index page

Balanced vs Unbalanced Audio / TRS / XLR

Balanced audio cables will give you a better, cleaner signal than unbalanced cables.
Ie less noise.

Unbalanced (2 wires):
TS cable
TS stands for Tip Sleeve.
Tip = signal wire
Sleeve = ground

 RCA cables


 As the audio signal goes down the cable, it can pick up noise.
Therefor dont use in long cable situations (greater than 25ft)
There are just 2 wires in the cable.
1. signal wire
2. ground wire
The ground can act like an antennae picking up unwanted noise along the way.
Most of the noise comes from power cables.
Thus, try to keep the power cables away from your audio cables.

Balanced (3 wires)

1. Hot signal wire (positive)
2. Cold signal (negative)
3. Ground

Wires 1 & 2 have opposite polarities until the end when the polarity of the cold signal is flipped back
to match the hot signal.

 TRS
Tip, ring sleeve
Tip = hot
ring = cold
Sleeve = ground

XLR


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There are lots of variations of this cable.
 This is a 1/4" TS to 3.5mm TRS Mono Interconnect Cable.


It's designed to apply a mono signal equally to a mini stereo phone input. It may be used to connect a mixing console to a portable media player, laptop

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If  you wish to wire a male XLR cable to a unbalanced monojack 
Pin 2 is HOT / Positive
Connect this to the tip of your jack.

Pin 1 is ground/shield.
Pin 3 is your cold / negative
Connect Pins 1 & 3  to the sleeve


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The reverse is of course the case for a female XLR 



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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Click here to access the Video Index page

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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Click here to access the Video Index page

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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Click here to access the Video Index page

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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Click here to access the Video Index page