Showing posts with label diodes. Show all posts
Showing posts with label diodes. Show all posts

Saturday, 2 March 2024

CMOSC - Drone Oscillator - Build notes - Nonlinear Circuits

These are my build notes for the Nonlinear Circuits CMOSC module
Its a eurorack format module.

CMOSC is an updated version of the 
4U CMOSC (CMOS drone Oscillator). 

Each module has 6 oscillators; the frequency of each
oscillator can be set with the pots. Feeding a signal to 
input will decide which oscillator signal will appear at the output. If the signal is low, oscillator A is heard, if the 
signal is high oscillator B is heard. 
This module gets very interesting when the outputs of each oscillator pair are fed into other pairs, which are themselves controlled by others and so on…..complex, evolving drones. Put
patchcords into every jack so every pair is controlled by another pair, listen to one of the outputs, twiddle the knobs until you feel satisfied.
The sync input actually disables the oscillators, the unmarked output is a sync output…or if you like; it goes high when the oscillators are disabled. It is most interesting to put an audio signal into the sync input, preferably from the other CMOSC module




The Eurorack CMOSC also  consists of 6 oscillators. 

each can be switched between two frequencies set by a single pot. When the pot is in the mid-point the two frequencies are about the same. Turn the pot to min or max to switch between higher and lower frequencies, or lower and higher. 














It's a gated oscillator.
Meaning  Each oscillator controls the switching of its subsequent neighbour
 (1-2, 2-3, 3-4, 4-5, 5-6, 6-1) via the switching pins of the input jacks. 
Patching in a signal will break this cacophony and allow you to have some control over proceedings.

Links
+ BOM







No hard to find parts



A single atom deprived of vibration could wreck the universe.
William Walker Atkinson

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"there's only so much you can do with a op amp "... Paul S

CD40106 1 soic Mouser: 595-CD40106BM96 or 771-HEF40106BTD-T



CD4053 2 soic Mouser Part No: 595-CD4053BM96 or 771-HEF4053BTD-T



TL074 or TL084 2 Soic Tayda: A-1140 or A-1137


LL4148 x 7 sod-80 Tayda: A-1213
BC847 x6 SOT23-3 Tayda: A-1339 
Resistors: 1k, 10k, 100k, 220K



The two 5V1 Zeners (SOD80) are optional...
The function of these 2 zeners is to keep the output of the summed stage to 
exact Eurorack …ahem…‘standards’.
The individual outputs generally swing between +/-5V (so 10Vp-p) anyway, which is pretty much
within the "standard range so I don't think I'll need them.
(The pads for the 5V1 zeners are there if I change my mind).
The summed out is very noisy and raw.



I'm using a VISHAY TZM5232B-GS08 from Tayda (X-4504) instead of the 5.1V
Zener Single Diode, 5.6 V, 500 mW, SOD-80 (MiniMELF), 2 Pins, 175 °C, Surface Mount
I'm hoping this will be enough.





I'm using a 10R instead of the Schottky (for the rectifier).
Just don't plug the power supply in backwards. 

caps
C1-C6 set the frequency range for each oscillator. 470nF gets down
to approx. 15Hz, so is probably the highest value you want to use
(assuming you want to keep things in the audio range). 
Andrew says its OK to mix values or keep them all the same.
I've decided to use all 470nF. Ill see how this sounds, then might experiment later.

*** I started to experiment with these caps. Changed C1 , C2, C3, C4 to 220nf.
      the drone was more audible*****


The other caps are 10uf and 100nF


Soldering the headers that join the two PCBs.

Pots & jacks.


You're done 




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You can find more NLC builds here.
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Saturday, 8 October 2022

Thermin- part 3 build - completion

This is part 3 of the Thermin build.
The earlier parts are  here:
Part 1
Part 2:
 
This is the build so far.
Resistors, caps, IC headers, trimmers are in.



There are two types of Diodes:
1n4004 x 4
1n4148 x 2
.

The 1n4004 form a bridge rectifier.
 
 The power supply is a 12V AC  job.
These rectify the AC to DC.
 
 It can also be powered with a DC battery.
But don't use a 12DC switchmode power supply
 
 
 
 
 
 
 
 
 
 
 
 
 
These are replacements for the inductors used in the original schematics.

IF oscillator Coil.
Its commonly used in radio receivers.
These coils can be bought to different specs.
Usually colour coded

In this project a black and 3 white are used.
..
The IF coil  is also known as an inter-frequency transformer.
The basic characteristic of every coil is inductance.
Their inductance can be adjusted by stretching or squeezing the coil turns.
 
The metal casing contains two coils. 
The first coil on the left is connected to a capacitor forming an oscillator circuit. 
The second coil transfers the signal to the next stage.

Install the voltage regulator.

Its a 7809 delivering 9V to the circuit.
final components... volume pot, power jack, switch, etc
 
 
 .... first tests
 

 

The antenna.Volume plate.
Its made from 1mm gauge aluminium.
 
                                                                                          Pitch antenna

connect speaker.


..
Tuning
The T1 reference coil doesn't need much adjustment.

 

Friday, 9 September 2022

Thermin - Silicon Chip - build pics 2

Some build pics of the Silicon Chip Thermin.
 
This kit has been sitting in the bottom of a draw for about a decade and I only dug it out
after a friend asked for advice re building a thermin from the old Moog designs.
Though this kit isn't the same I thought I'd finally put it together to learn about thermins in general.
I think this old Jaycar kit is discontinued.
 
This looks like a very easy project that

is great for beginners.
All through hole components.
This is part 2 of my Thermin notes.
The first part of the build notes are here:
 
I'll discuss the circuit as I build the synth.
All Thermins start with this same basic circuit.
 
The basic circuit comprises 3 oscillators (reference, pitch & volume).
In this case they all operate at 455kHz.
Each oscillator is essentially identical.
They comprise a JEFT (junction field effect transistor) and a pre-wound IF (Intermediate Frequency) transformer. 
The JFETs are all 2N5485.
In this case the Reference oscillator = Q1 & T1 
The Pitch Osc = Q2 & T2
Vol Osc = Q3 & T3
 
The original Moog circuit used 2N 168 & 2N1086 transistors.
These are old GE  intermediate- and high-frequency transistors intended for use in radio receiver circuits.
I reckon these would be difficult to find today. 
 
 
T1,T2 & T3 are the pre-wound IF (Intermediate Frequency) transformers.
These are a modern substitute for the inductors used in the vintage circuits.
Looks like you can buy these on Aliexpress, etc
 

The Tone Oscillators (ref & pitch)

The Reference & Pitch Oscillators are mixed in IC1 (called the product detector) to produce a audible tone.
IC1 = MC1496
It's a balanced modulator/mixer.
You won't find this in the original Moog circuit where the two oscillators are mixed through two capacitors and rectified through a diode.
 
Its a pretty common chip .
Pretty old ... dates I think from the 1970s. Easy to find on Ebay.
The MC1496 is used here as a mixer.
The signal inputs are on pins 1 & 4 .
Carrier inputs are pins 8 & 10.
Outputs are pins 6 & 12.
 
The deeper I compare this circuit with the original Moog circuit, the more I realise
how components have changed over the last 70 years.
I guess this is to be expected.
I wonder if its practical finding all those old vintage parts if you wished to stay true
to the original schematics.

Anyway, back to the build.
The VR2 trimmer looks like an new addition to the original circuit..
I think this is a basic wave shaper ???
It varies the coupling between the pitch & reference oscillators that produces the final voicing
& adds some waveform distortion. 

The addition of this shaper circuit changes the final timbre.
It can now be varied from a pure sinewave (which is not characteristic of a Thermin) to  a much deeper sounding square/ramp tone, which I think has a lot more harmonic content.
 


The output from IC1 is fed into IC2.
IC2 is a LM358 op amp.
It acts like a low pass filter.
Again, you won't find this in the vintage Moog Thermin. 
That circuit has no ICs. Its all transistor based.
 

The output from the filter is applied to the power amp (IC3, LM386)
 and this drives the speaker.
 
IC 3 = LM 386
IC 2 = Lm 358
IC 1= MC 1496



The Volume Oscillator.
This is made up of  T3 & Q3
The secondary winding of T3  is connected to the base of Q4 (BC548)

The collector of Q4 is  attached to T4 (and its capacitor).
T4 is another IF coil.

To be continued ......

Thermin- part 3 build - completion

 PS: do let me know if there are any mistakes or omissions. Cheers Jono

Tuesday, 5 June 2018

Diodes - Basic Info

The name diode is derived from “di–ode” which means a device that has two electrodes. 

These belong to the world of "semiconductors". 
Semiconductors are usually broken up into positive or P-type, and negative or N-type. --- this has nothing to do with the poles of a battery. The two types are joined together.

Orientation



A diode is a two-terminal electronic component that conducts current primarily in one direction; it has low resistance in one direction, and high resistance in the other. Wikipedia
They allow current to flow in one direction.
See the arrow.
A PN junction is the simplest form of the semiconductor diode.
 
 
 Semiconductor diodes are the most common type of diode.
 
Different Types of Diodes
  • Small Signal Diode. ...
  • Large Signal Diode. ...
  • Zener Diode. ...
  • Light Emitting Diode (LED) ...
  • Constant Current Diodes. ...
  • Schottky Diode. ...
  • Shockley Diode. ...
  • Step Recovery Diodes. (Snap-off)
  • PN Junction Diodes
  • Tunnel Diode (Esaki)
  • Varactor diode (Varicap)
  • Photo diode
  • PIN diode
  • Lazer diode
  • Avalanche Diode 
  • Vacuum Tube diodes
  • Crystal rectifier (crystal diodes)
  • Gunn Diodes
  • Thermal Diodes
  • Stabistors or Forward Reference Diodes 
  • Gold-doped diodes
  • Super barrier diodes
 Common Diodes you will use are Schottky, LED, Signal, photo and Zener

Schottky Diodes
Very commonly used in Synthesizers.
The main application area of Schottky diodes is in switching power supplies which are intended to work with frequencies over 20kHz.

They are also known as barrier or hot carrier diodes. 
They have their own symbol.

It has a low forward voltage drop and a very fast switching speed.  
The forward voltage drop is substantially less than that of the conventional silicon pn-junction diode. 
 
 
A silicon p–n diode has a typical forward voltage of 0.6 – 1.7 Volts, while the Schottky's forward voltage is 0.15– 0.45 V. This lower forward voltage requirement allows higher switching speeds and better system efficiency.  
 

 
These are all different types of Schottky Diodes







..


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Photo diodes
A photodiode is a PN-junction diode that consumes light energy to produce an electric current.
It's designed to absorb photons.
 They are also called a photo-detector, a light detector, and a photo-sensor. 
Photodiodes are designed to work in reverse bias condition. 
Typical photodiode materials are Silicon, Germanium and Indium gallium arsenide.





In the NLC Lux module, its used to make a "optical thermin".






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