Wednesday, 31 October 2018

Vector Rescanning - Rutt Etra - Tek 620 monior - first attempt

Initial efforts on getting some vector rescanning.
I'm using a LZX video synth and a Tektronix 620 monitor.

...


 tHE patch is very simple.
Horizontal ramps into the X input.
Vertical ramps into the Y input
Video from the camera into the LZX "Color TBC" and out via the Color video encoder.
This video signal is then plugged into the Z input

 The Passage, Bridge are boosting the signals
-------------------------

Patch 2

Slight variation on the first patch.
I'm now mixing the video signal into all 3 inputs.
Ramps and still going into the X & Y ins

....

Links:
LZX official
Muffs - Cadet series DIY/assembled

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Click here to access the Video Index page

Tektronix 620 monitor

Finally arrived.
And she survived the postal service.
 i'VE no idea what the Thomson module on the right does.
If anyone can help provide and info, manual, etc , I'd be very grateful.


This runs on 110V

I'm planning to use this to try vector rescanning.
It has the X, Y and Z inputs so hopefully it will work.








LZX Cadet X - DIY Video synthesizer - Multiplier

There is a old saying in the audio world: "You can never have enough VCAs"
Maybe this is a bit simplistic, but I'm seeing the Multiplier as a VCA for video.
(its much more than this too).

These are 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.10 (Multiplier X).
It doesn't require the 14 pin sync cable.

It's described as "Cadet X Multiplier is a variation on the Cadet VI Fader circuit,
 configured as a switchable 2-quadrant or 4-quadrant multiplier".
So if I understand this correctly, in 2-quadrant mode it it acts like a VCA and in 4-quad mode it behaves like a ring-modulator..... "it crossfades between an inverted version of the input signal
and a positive version of an input signal"

2-quadrant mode = VCA.
You can control the amplitude with a control voltage (0 = no signal & 1V = max signal)

4-quad mode = Ring Modulator
The amplitude of the output is again controlled by CV.
When CV is negative ( -1V for LZX = max inversion) signal gets inverted.
When CV is positive  ( +1v on LZX = max amplification) signal is non-inverted.







This video amp ic is out of stock at mouser. (marked U2 on the PCB)
584-LT1251CN#PBF
LT1251CN#PBF 

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

LT1251CN#PBF - iTS a 40MHz Video Fader and DC Gain Controlled Amplifier
It's probably the core component of this module. Looks very useful if you are designing your own circuits like the fader and amp below. But its not cheap. Mouser sell them for $16 AUD each.

And yes, this same chip is used in the Cadet VI Fader module.





ICs and special parts:
TL072IP
LT1251CN#PBF  ---- 40MHz Video Fader and DC Gain Controlled Amplifier
LM6172IN/NOPB
TL431BQLPR

to be continued ... waiting on some parts

Links:
LZX official
Muffs - Cadet series DIY/assembled

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Click here to access the Video Index page

LZX Cadet IX - DIY video Synth - VCO

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.9 (VCO IX).
LZX describe it as a wideband triangle core VCO.

 ic'S used:
LM6172IN/NOPB --- this is a dual op amp... specified at ±5V power supply for low
                                 voltage applications such as portable video systems.
TL431BQLPR ----- Adjustable Precision Shunt Regulator
                               TL431 shunt regulator circuit explained 
TL072IP - standard op amp
SN74HC14N - it's a hex schmitt trigger
CD4066BE - CMOS quad bilateral SPST switch
 ----------------------
I'm guessing that the SN74HC14N is being used as the schmitt trigger oscillator.
If I'm reading the schematic correctly, a square wave is developed from the Schmitt trigger and the triangular wave is developed across a capacitor. They are output through buffer amplifiers (LM6172).

This same IC is used in the Cadet IV Dual ramp generator

(Another IC that would probably do a similar job is the 40106  - also a Hex Schmitt-trigger Inverter..
or a 74HC4046... phase locked loop ??? ................... a couple of thoughts for another day)

 DPDT & SPDT switch (on on). These aren't right angled, so I'll have to hand wire them.
We nEED  matched transistors.
I had to do something similar many years ago for an ARP 2600 clone ... the TTSH
 http://djjondent.blogspot.com/2014/08/transistor-matching.html



R43 -- I could use a TempCo but instead using a standard 2K resistor
Resistor 43 = tempCo?
 I decided not to use a TempCo in this case. Just used a standard resistor. I like my VCOs to be untuneable. :-)

 The 10k pots finally arrived. I had trouble finding these. (I got them from thonk)




ICs , parts etc used in this project:
LM6172IN/NOPB
TL431BQLPR
TL072IP
SN74HC14N
CD4066BE


Mods:
+There is a Square output on the C9 circuit. You can output it directly or use it with the triangle to drive a sawtooth waveshaper circuit.

Links:
LZX official
Muffs - Cadet series DIY/assembled
7414 oscillator -DIY
How Video Oscillators work - Muffs

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Click here to access the Video Index page

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

---------------------------
Click here to access the Video Index page

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