Friday, 30 January 2015

Flying Fox - Jodhpur - India

What a great way to see the fortress of Mehrangarh in Jodhpur, India.
Flying over these magnificent battlements is so exciting.





Zip 6: The Magnificent Marwar (300m) You fly over two lakes an land on the tip of a fortified tower that rises 30 metres out of Ranisar Lake.

Battlements of Rajasthan

 Flying Fox - cable - over Mehrangarh Fort.


The medieval "Blue City" of Jodpur.

Thursday, 29 January 2015

TKB Build - 4 - main PCB - Semi-conductors

*** Click here for the TKB Build Index ***
 
The diodes (6x 1n4148) are already in. Transistors & integrated circuits to go.
The main board uses 10 transistors:
One PN4250 & nine PN5179. (my vintage TKB uses nine EN5179s)

 This is a pic of a vintage EN5179.

Today the PN5179 and EN5179 are very hard to get, so they have been replaced with the more common 2n3904.



The PN4250 is unchanged from the original.

There are 9 types of ICs used on the main board.
These are:

1. LM324N. We need 4 of these.
     Mouser #: 512-LM324N    
     Manufacturer: Fairchild Semiconductor
     This is a quad Operational Amplifier.

2. 4042. We need just one of these
     Mouser #: 595-CD4042BE   
     Mfr. #: CD4042BE
     Manufacturer: Texas Instruments
    This is a CMOS quad clocked D-type latch.
For more about latch circuits click here:
http://www.dummies.com/how-to/content/electronics-projects-how-to-build-a-latch-circuit.html

 3. 4050. We need 3 of these
      Mouser #:     595-CD4050BE    
      Mfr. #:     CD4050BE
      Manufacturer:     Texas Instruments
     This is a non-inverting hex buffer.
    
Some info on buffers:
http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/buffer.html

 4   4051. We need 3 of these.
      Mouser #:     595-CD4051BE     
      Mfr. #:     CD4051BE
      Manufacturer:     Texas Instrumen
    
      The CD4051B is a single 8-Channel multiplexer having three
       binary control inputs, A, B, and C, and an inhibit input. The
       three binary signals select 1 of 8 channels to be turned on,
      and connect one of the 8 inputs to the output


5. 4069 - We need two of these.
      Mouser #:     595-CD4069UBE    
      Mfr. #:     CD4069UBE
      Manufacturer:     Texas Instruments
      The 4069 contains 6 CMOS inverter circuits.

     For more info click here:LOGIC INVERTERS
   
    

6. 4081 - We need two of these.
     Mouser #:     595-CD4081BE     
     Mfr. #:     CD4081BE
     Manufacturer:     Texas Instruments
     This is a Quad 2-Input. AND Gate.

For more info on Gates click here: LOGIC Gates
7. 4516 - just one is needed.
    Mouser #:     595-CD4516BE    
    Mfr. #:     CD4516BE
    Manufacturer:     Texas Instruments
    Desc.:     Counter ICs Binary Up/Down


8. 4520 - We need just one.
    Mouser #:     595-CD4520BE   
    Mfr. #:     CD4520BE
    Manufacturer:     Texas Instruments
    Desc.:     Counter ICs Dual Binary Up

9.  MM74C150
     This is a 16 line to 1 line Multiplexer
      Datasheet info

Part 5. Pot boards.
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*** Click here for the TKB Build Index ***
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Wednesday, 28 January 2015

TKB Build Notes - Index - The Human Comparator Kit

TKB Build Notes - Index - The Human Comparator Kit.
This is the main Index for the build notes for the Serge TKB (Touch Keyboard Sequencer).
Many thanks to Zthee (The Human Comparator) for making this build possible.

I'm documenting my experiences as I put the TKB together to help me trouble shoot in the future .
Hopefully, this will also help others in their quest to build the TKB & more importantly, to learn the
Art of Electronics & of Electronic Music.

1. Pics of the kit before starting.
2. Some pics and info of a vintage TKB.
3. Starting the build - main PCB -  resistors, diodes, headers, caps, etc.
4. Main PCB - Transistors & ICs
5. Pot boards.
6. The Touch Keyboard (Installing the LEDs)
7. Front panel assembly.
8. Wiring up the touch keyboard
9. Installing the S2 & S3 Ribbon cables.

This index will be updated as the project progresses. 

The official build notes of the Human Comparator
http://build.thehumancomparator.net/ 

The original build notes for the TKB kit from the 1970's are here:
http://serge.synth.net/documents/kit/tkb.html 
Official modifications to the TKB from the1970's are here:
http://serge.synth.net/documents/kit/tkbmod.html  
Intro to the Serge Modular Music System
http://www.serge.synth.net/documents/Intro_To_SMMS_Part_1.pdf

Muffs has a great thread here:
 https://www.muffwiggler.com/forum/viewtopic.php?t=104513&start=575
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Zthee's previous project was the TTSH (Two Thousand Six Hundred).
This is a clone of one of the greatest synthesizers of all time, the mighty ARP 2600.
My build notes for the TTSH are here:
TTSH Build Notes




TKB Build - Part 3A - Main Board

TKB - Touch Keyboard Sequencer - Build Part 3 - Main Board. (Resistors, Caps, etc).

*** Click here for the TKB Build Index ***

Before we begin there are some preliminary pics of the PCB


I'll start of with least temperature sensitive components such as the IC header sockets, resistors & diodes.



Mouser #: 571-5103308-3
Mfr. #: 5103308-3
Manufacturer: TE Connectivity
Desc.: Headers & Wire Housings 16P 2 ROW HEADER LP
These modern headers connect the Main PCB to the rest of the keyboard. In vintage TKBs, the headers used were slightly different:


Notice the silver arrow which is used to check the header orientation.
Vintage TKB headers.

Back to the Modern PCB: 

Looks like the four 22pf caps on the left need to be swapped for 100pf.
According to one of my tech friends, you can experiment a bit here. Serge used 82-100pF,
but you could even go as high as 220pF. Apparently the caps are filtering some unwanted noise from the clock driving the keys, and 100pF suppresses it OK. ....but even higher values might do a better job. The only problem is - go too high and it might start to slew your signal… ????

I'll def do some experimenting with this. (Many thanks to my friend for this advice).

Looks like the surface mount 100n caps need to be soldered to the underside of the PCB across pins 5/4 & 11/10.  of the  LM 324s --- SEE PIC BELOW

The LM 324 is a low power quad Op-Amp


There are 5 surface mount 0.1uF / 100nF caps to solder to the underside of the PCB.
The soldering points are a bit tricky to see at first. They lie across two of the LM 324s -  pins 5/4 & 11/10.
and underneath the LM324 just below the MM74C150


The SMD caps lie under the three LM 324s on the top right

Almost finished the easy part ... soldering the resistors, diodes, caps & headers..
I think its a good time to stop and compare this board to a vintage TKB main board. This one is a unrestored TKB -- also from the late 1970s.

Notice the bud box below is self powered.... in fact it has two PSUs, and was once part of a much larger system.

 Top pics of the main TKB PCBs (vintage on left)

The underside of the PCBs.


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*** Click here for the TKB Build Index ***
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Monday, 26 January 2015

KORG Rhythm 55 (KR-55) Drum Machine

Korg released both the KR-33 & KR-55 in 1979. They are the successors to Korg's successful Mini Pops series of drums. The KR-55 looks a bit like a old school calculator, but don't let it's appearance fool you.
 This was quite cutting edge for its time.  There is a micro-processor involved in rhythm making. Gone are the days of the old diode matrix.


Its built in sequencer has 48 preset patterns (Waltz, Samba, Cha Cha, Afro, Enka, Rhumba, Bossa Nova, Tango, Slow Rock, Swing, Rock, etc.). There are 16 Intro patterns & 16 Fill-In patterns though sadly you can't  program your own patterns. (Roland had  just brought out the CR-78 one year earlier which had this feature as did the Roland TR-606 which  wouldn't come out till 1981).


There are 12 analog sounds: Bass Drum, Snare Drum, 2x HiHat, Cymbal, Low Conga, High Conga, Rim Shot, Claves, Cowbell, 2x Tom Tom. The sounds are commonly described as snappy & metallic.

Here is a great video I found on youtube which gives a really good example of these sounds.







The rhythms are not mixable like on some of the old Minipops drums, but the tempo and volume knob do allow for a little tweaking. There is also a "swing" control to add a bit of spice to the groove.

 In his excellent SOS review, Gordon Reid discusses the TR-33 & TR-55 "History of Korg - Part 1"

"More successful [than the Sigma] were the KR33 and KR55 rhythm units, which replaced the ageing Mini Pops series. These were more sophisticated than their predecessors, generating analogue sounds that were far more realistic than the noise-based thumps and hisses offered by the earlier DoncaMatics, Mini Pops, and units from competitors."

Here is the Korg KR-55 manual


There is a Trigger out , but no trigger in. Thus un-modded, it's impossible to sync with external gear. There are several triggering modes: I understand that The KR-55 runs at 8ppqn so you will need to use a clock divider if you wish to sync it to midi or sync24.
  
It can also be externally controlled via the footswitch jack for the Start/Stop & Intro/Fill switches.


There are no individual outs for the 55 but there are faders for most of the drum sounds.that allow you to mix the volume levels of the bass, snare, cymbal, hi hat, conga/TT, Rim Shot/Cow Bell/Claves.
There are lots of mods on the net on how to get individual outs.

The Korg Rhythm 55 was used by Jean-Michel Jarre (Magnetic Fields) and Depeche Mode  in 1981 (Speak and Spell) & Cabaret Voltaire.

Modding:
Analogue solutions midi kit looks nice but has a fee of £109 for the kit.  I may end up doing it but would love individual outs along with it.
http://www.analoguesolutions.org.uk/mods/kr55.htm 

http://www.youtube.com/watch?v=33zfpZ9RBK8

Here is a great place for some modding (esp for multiple outs) :
http://alienatedsynthesist.blogspot.com.au/2011/10/kr-55-clock-in-mod.html
https://www.flickr.com/photos/31603983@N05/sets/72157628641466671/ 

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For more info on the history of Korg Drum Machines Click Here  

Sunday, 25 January 2015

Korg SR-120 (Mini Pops 120) Drum Machine.

The Korg SR-120 came out in 1976.
In that same year Korg also produced the Mini Pops MP120, the Mini Pops MP35  & the Mini Pops MP 45 Rhythm Machine.
The SR-120 is identical to the MP-120. This was the final drum which Korg produced under the mini pops label.... and was supposed to be their best. It has all the bells and whistles.


She boasted 6 sounds (BD, SD, Cy/HH, low conga, high conga, claves) and 16 presets (slow rock, swing, bossa nova, beguine, rumba, mambo, samba, waltz, tango, polka, foxtrot, march, rock 1 to 4).
making 32 patterns.
The sounds esp the Kick are awesome.

The Korg 120W

This version has a wood case, but they also came covered with tolex.
The cube shape also seems to be catching on both with Roland & Korg. Roland's CR78 is just two years away.

Korg, in addition to the tolex version, re-branded these as Univox SR-120s which came in a road case with lid & handle (the 120-P).
 https://www.youtube.com/watch?v=bb9n2PhmfCo
Another important point to make about the 120 is its use of a ROM (read only memory) chip to store the patterns. Looks like the identity of the ROM is a AmericanMicro Semiconductor uPD471D

UPD471D

The Roland CR-68 & 78 also followed this trend with ROM chips too.
Earlier machines of both companies used what's called a diode matrix to store the patterns.

The mini pops 120 schematics indicate the use of both a diode matrix and a ROM chip.
The diodes are easy to fix. However replacing a integrated circuit made in 1976 is much trickier, if you can't find a replacement chip.



There are lots of mods for this machine if you can find one that works.
A good place to start is here:
http://www.estecho.com/gear/Korg_Mini-Pops_120.php
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For more info on the history of Korg Drum Machines Click Here

Udaipur - India

This is such an underrated place.
So very very beautiful. Reminds me of Venice.
It's quite a big city with lots to see.

Give yourself at least 4 days. A week would be nice.
Some pics of the water front:
 Panorama from one of the bridges.

 It's New Years Eve: the calm before the storm.

Udaipur is very romantic. It is  the historic capital of the kingdom of Mewar,
in the state of Rajasthan
Udaipur was founded in 1559 by Maharana Udai Singh. With the  emergence of artillery warfare in the 16th century it was decided to move the capital to a more secure location... away from the old fortress of Kumbhalgarh.


 Roof top nightclub. The perfect place to see the New Year in.


Lobby of the Lake Pichola Hotel

The lake Palace is in the distance.
The Lake Palace covers an entire island in the Pichola Lake.