Friday, 14 September 2018

Vectrex - Game

New Toy !
This dates from 1982.




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Vectrex was the first company to bring vector graphics to the home audience via a vector monitor.
This was a time when most arcade games used vector graphics. (for instance in Asteroids and Space War), different from the raster technique used in most home video games that connected to televisions. Vector graphics are essentially lines of light. Raster graphics consist of small pixels or blocks.

The built in game, Minestorm is a derivative of Asteriods.

I remember playing asteriods on an Atari back in those days and the vectrex is probably the closest thing I'll get to experience this today, short of buying a vintage arcade machine.
This video is a very cool... recreating asteiods with lasers:
https://www.youtube.com/watch?v=FkHjG759ABY


So I'm lucky to have found a working vectrex.
Considering if I should mod it or leave it alone.
Will probably mod it.
I'm interested in using the monitor for video synthesis.

One peripherial I don't have is the light pen.
There are however a few sites with hacks for making my own.
 http://www.playvectrex.com/vectech/mvlp/mvlp_f.htm
and:
https://www.youtube.com/watch?v=6On2AFPx6pc

The working end of the pen is a cheap silicon L14G3 phototransistor


The other periphery are the 3D glasses.
...so so rare. This 3D system predated the Sega Master System's SegaScope 3D by about four years.

The monitor is Black & white.
Every game came with its own coloured and transparent overlay, that could be attached to the screen.

Specs:
Manufacturer:  Western Technologies/Smith Engineering which was a videogame company started by  Jay Smith, an engineer who was previously an employee at Mattel. It was licensed and distributed first by General Consumer Electric (GCE), and then by Milton Bradley Company after their purchase of GCE.
The Vectrex was known as Bandai Vectrex Kousokusen in Japan.

Release year: 1982
Discontinued :1984


MPU: Motorola 68A09 (MPU= Microprocessor)

It's a DIP-40 8-BIT MICROPROCESSING UNIT.
On the actual PCB it's IC206.

Frequency The MPU operates at 1.6 MHz from a 6 MHz external Xtal. 
                   An internal divide by 4 circuit generates the MPU 1.6 MHz "E" clock signal 
                   used in the system

ROM: 8KB  (one 8-bit 2363 chip) ,  4KB used by Minestorm.
          On the actual pcb the ROM chip is IC201. It's the sharp 284001-1

RAM: 2 x 1KB (two 4-bit 2114 chips). These RAMS provide storage locations for data
         indicative of locations of objects, game status, and various other information 
         needed by the microprocessor during game operation. (IC 204 & 205)

Sound: 3 channels through a General Instrument AY-3-8912 sound chip
            You will find this chip on the Logic board. It's IC 208.
            3" electrodynamic paper cone speaker.
            3 voices (all square wave). 1 noise generator

Media:  ROM cartridges 32KB

Display : 9 x 11 inch CRT (240mm diagonal), Black & White monitor. Samsung model 240RB40
              Resolution: 330 × 410


WEIGHT: 15 Lbs.

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The standard TTL device types 74LS00 and 74LS32 are used as control line decoders to allow the MPU to select the appropriate circuit element to be addressed at any particular time.
The 74LS32 decodes logic to perform read and write access to the RAM by the processor . The 74LS32 is a Quad-ORgate. (IC203). Its obsolete so you have have trouble finding replacements.
The 74LS00 is a 2/IN NAND gate. (IC202) .


**Any TTL chips you find with the code 74LSxx are Low power Schottky and date pre 1985.
They were superceeded by chips using the code  74ASxx - Advanced Schottky.
TTL stands for Transistor–transistor logic. Its a logic family built from bipolar junction transistors. Its name signifies that transistors perform both the logic function (the first "transistor") and the amplifying function (the second "transistor")**

The analog processing section includes digital to analog converter (DAC) chip type MC1408, dual 4 channel multiplexer/demultiplexer chip type CD4052, and dual channel op-amps types LF353 and LF347.

The DAC chip 
(Digital to Analogue Converter) MC1408 receives an 8 bit word at data terminals D0-D7. DAC output (pin 4) is current source. This IC is responsible for graphic output
 
One section of IC LF353 is used to change this current to a voltage representative of the 8 bit digital word received by the DAC chip. The LF353 voltage is applied to an input of the dual 4 channel CMOS multiplexer (MUX) chip CD4052. This same voltage (designated "DAC" on the schematic) is the X-axis drive signal. 

The CD4052 MUX chip serves two purposes: it selectively couples, under MPU control, the output of the DAC current/voltage converter to one of 4 places and is used to selectively couple the inputs from the joystick pots to the voltage comparator IC LF353.

 --------------------------------------
If you are having any problems with the joystick interface try replacing the AY-3-8912 sound chip.
You would think that the 6522 Versatile Interface Adapter (VIA) is the obvious choice for the joystick interface, but  it turns out to be connected to the General Instrument AY-3-8912 which also has an 8 bit IO port. 

(The above information is from the Vectrex technicial manual).

Saturday, 8 September 2018

246r Sequential voltage source - buchla format - part 2 build notes

These are my build notes for the Roman 246r 
It's a pretty big build ... as are many Buchlaesque  builds 
so I've decided to split the build notes into a few posts.
Part 1 of the build is here:
 
 below is board 2 

 

The module called officially the 246r sequential voltage source.
It's a Buchla format sequencer.



 These are just my personal build notes.

I'm not a pro technician. 
These pics and notes as just to help me trouble shoot should I run into any problems.

  
Dave Brown has an excellent page on his mods of a 246.
Ive decided to try this.

Stage CV Input

PCB2:
With 16 stages there are no unused gates with floating inputs.
Add a 100 pF capacitor across R65.

I added a ceramic 101 cap

 
 

----------------------------

Stage CV Output Level


PCB2:
Change R294, R296, R298, and R317 to 330K.
 

Don't install C57, C58, C59, C61.
 
Replace R288, R289, R290, R307 with a link.
*photo
 
 
I did install the rest of the caps




0.1uF F1 - 
F38 38 CERAMIC 5MM LS 
581-SA105E104M
decoupling ?


Next the SMD caps
15uF 
C3, C64, C65, C66, C67 
5 TANTALUM SMD CASE D 
Mouser 74-TR3D156K035C0150



 
and the voltage regulator

---------------

Stage Pulse Output Level

On PCB2:
Change R55, R61, R72, R78, R86, R92, R100, R106, R114, R120, R128, R134,

to 6.8k


Again on PCB 2 change
 R142, R148, R156, R162, R170, R176, R184, R190, R198, R204, R212, R218, 

to 6.8k

Finally,
Change on PCB 2
R226, R232, R240, R246, R254, R260, R268, R275 
to 6K8


(I'm using 6.81K 1% tolerance with all these changes)
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Wednesday, 5 September 2018

NLC - CellF Voice - Build notes

I've had this PCB/panel for 4 years... finally getting around to building this.

I finished the companion to this about a year ago, the CellF action.

These two panels were developed for the cellF neural synth project where a synthesizer was made to be controlled by live human neuron cells.


Some pics of the virgin PCBs

The CellF action build uses smd resistors, caps & ICs.
All transistors are thru-hole. 
 

The PCB is very large 


Each board has. 
2 tri-core VCOs 
2 LFOs 
2 LPGs 
3 VCAs 
VC spring reverb 
diff-rectifier 
jerkoff chaos 
2 281 EGs 
Sauce of Unce. 
Pots and sockets mount on PCB, no wiring (except to reverb tank). 


I'm building version 2.0  

 I usually put on the ICs first, as these are the most fiddly.

Regarding the NJM13700 .

I'm using   regular LM13700 SOIC . they will fit (in addition to some NJM13700s)
These are transconductance amplifiers.


I'm using 470 ohm resistors for the LED resistors (RL)



There are 2 CMOS chips used in the build: 4001 & 4066

Using these 10V zeiners

The 10V voltage regulator: 7810

JFETS: using J112 x 4

Vactrols:
Using 2 types:

The single vactrol NSL. the white dot marks the cathode.

VTL 5c3/2..... I used them a lot in the buchla "clones"
The sloped edge marks the cathode. The cathode is labeled on the PCB with a K.


The Dual LED has a common Cathode. Its orientation doesn't matter.
Check the led fits in the panel hole before putting it all together. I had a batch of duals that were a bit big and the needed 0.5mm drilled out.


almost there.
Final tests.

Notes:
+ NLC blog
+ Build notes - official version 1.3
+ Voice - prototype working 


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You can find more NLC builds here.
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Zlob - Dual VCO

Some pics of a recent build.
This is the ZLOB dual VCO.
 These aren't really build notes. Just pics to help my future trouble shooting.
The official ZLOB site is here: https://zlobmodular.com/


The VCO is a 4hp dual analog oscillator. Each VCO is CV controllable & has square, triangle, and sine wave out, coarse and fine tuning controls.

There is a control voltage input, and a switch for selecting exponential or linear cv in.
The exponential setting should be good for Korg & Yamaha keyboards & sequencers 

My choice to build this really was determined by its size. I needed a small footprint VCO for my euro performance rig.

Each VCO runs from 0.2 hz (5 seconds a cycle) up to 18k hz.
So this should be good as an LFO. as well as  a VCO.

The waveforms are very Stable as its temperature compensated
The waveform outputs are 10vpp

When a control voltage is inserted, the fine tune control becomes an attenuator for the incoming voltage. 

 Accidental cut of trace. My fault.... to be fixed.
In exponential mode, when the attenuator is fully clockwise, the VCO will track around 5 volts per octave.




 I'm joining these with rightangled headers.



nOTICE THE PCB repair to the lower left.


tHE final component installed was the 2K tempco resistors. I used this heatsink paste.


LOvely.... the VCO worked instantly... no trouble shooting needed.
Love it so much I think I'll build another.




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These are some pics from a second building of this module.
Some of the parts are slightly different
 















IC:
The TL072 first

The two LF412 op amps next


The TL 074

 

Finally the two  8038 ICs








Official build notes:

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For more Euro DIY builds click here:
http://djjondent.blogspot.com.au/2017/12/diy-index.html
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