Neuron / Difference Rectifier PCBs

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andrewF
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Neuron / Difference Rectifier PCBs

Post by andrewF »

UPDATE 4/3/14 panels in stock, see pics below
10hp (pots mounted on PCB) AU$22
$5 shipping per order

DIFF RECTIFIER / NEURON BUILD MANUAL includes schematics & BOM


I keep getting asked about these so have sent off a design for a pcb containing 1 of each of these circuits. Ordered 100, so plenty to go around.
The Difference Rectifier has 4 inputs (two + & two -) and two outputs. The Neuron has two inputs and one output. There is a pad labelled 'ext' where extra inputs can be added if desired (use a 100k resistor attached to the jack).
All inputs for both circuits can be wired to attenuating pots if required. The two pots on the PCB are the critical Offset and Invert controls for the Neuron. The Offset is slightly modded from the previous Double Neuron PCB as it now ranges between +V and -V and its effect is halved by the 200k resistor, giving a greater useful range from the pot.
Schematics and demos - Difference Rectifier and Neuron


The PCB is small so will suit Euro builders. Approx 1.5 by 2 inches.
The 2 board mounted pots (both 100k) are 1 inch apart, the idea is to mount the PCB to the panel with threaded pots. There are 2 mounting holes otherwise if you want to attach the board some other way.

Expect AU$10 each including shipping anywhere, add AU$8 per board for extras. (ie 2 PCBs = AU$18 shipped, 3 PCBs = $26 shipped, etc)
Should be here in a month, please indicate if you want in this thread. I will pm and request payment once the PCBs are here, tested and ready to ship.

[video][/video]

[video][/video]

edit Batch 1 sent out to

frozenkore 4
rod serling fan club 4
Ringstone 4
appliancide 2
Cyklopljud 2
Glitchpop 2
Negativspace 4
ear ear 2
Themanthatwasused 2
willzyx 4
Boothnavy 4
Pfurmel 4
Asterisk 4
aL Pariah 4
defenestration 4
Raisinbag 4
Theabsent 8
Dreamlost 3
Janvanvolt 4
Lordofthebored 2
Fetideye 2
Luka 4
moogah 4
fluxmonkey 4
cleaning lady2

edit 6/3/2013
batch 2 shipped
boards shipped:
very angry mobster 4
dmitri 4
clorax hurd 3 + 3 double neuron
fonik 4
jjsynth 4
photon 2
rosch 4
Dego 4
iL 4
falafelbiels 2
withakay 2
spotta 4
rowman 4
pre55ure2
macumbista 4
synchromesh 4
limpmeat 4
transistor logic 2
synthcube 10
Attachments
n1.jpg
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n2.jpg
n2.jpg (262.99 KiB) Viewed 3459 times
DrN.jpg
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Last edited by andrewF on Tue Mar 04, 2014 1:22 am, edited 8 times in total.
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decaying.sine
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Post by decaying.sine »

4 PCBs for me please.
Brian
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Post by Pfurmel »

I'll take 4 of these also, if that's ok.
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Post by negativspace »

Same! Gotta have a couple in the Euro... can't have Neurons without euro after all. :zombie:
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wetterberg
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Post by wetterberg »

Please desrcribe these two circuits with words. Please.

I think I get the difference rectifier, but honestly an explanation beyond "look at the scope" would be lovely :)
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Luka
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Post by Luka »

Yeah i might grab a quad :sb: :sb: :sb: :sb:
defenestration
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Post by defenestration »

4 PCBs for me, thanks much!

what's the largest 'neural network' you've ever patched? even just two neurons feeding a third seems like it would be interesting. . . . or is it kind of a waste of time? I suppose it might depend on your perspective.
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Post by andrewF »

wetterberg wrote:Please desrcribe these two circuits with words. Please.

I think I get the difference rectifier, but honestly an explanation beyond "look at the scope" would be lovely :)
The Diff Rect....needs a better name, behaves as per these equations:

Image

Basically the voltage on Vin- is subtracted from the voltage on Vin+. The value left then goes to Vout+, if it is more than 0V, or to Vout- if it is less than 0V.
So, as the name implies you are getting the difference between the input signals and that difference is then rectified to the +ve or -ve outputs.

As there are no caps in the signal path, it will happily deal with audio rate signals as well, so is an interesting waveshaper and even acts a bit like a VCA....let's say audio gate :hihi:
For me it is most fun just to feed it signals from LFOs and get a lot of complex envelopes from it.

The neuron is from "A general purpose analog neural computer" by P. Mueller et al and modified for use in a synth. The circuit is an "idealized version of a typical biological neuron." It feeds thru the postive rectified portion of the input signal and mixes that with positive and negative going pulses (or spikes or gates) when the threshold (set by the offset pot ) is crossed.
The 1st op amp stage is a summing rectifier. This stage output is fed to a comparator, the inverted positive rectified signal and the comparator output, via an attenuator, are summed and inverted at the final output stage.

The offset pot determines when the comparator will 'fire' in response to the input signal and the invert pot sets the level of the signal from the comparator going into the output stage.

Sorry, this description probably doesn't help.

Trying to think of an analogy that may help....Perhaps it is like your partner tickling you, the tickling corresponds to the input signal, tickling with two hands is like two input signals. Most of the tickling makes you giggle and squirm a bit, but every now and then your partner tickles a sensitive spot, like that little flap of skin between your testicles and your anus, then you lose it, jump in the air and a bit of wee comes out. This is the equivalent of the comparator kicking in, sending the output signal haywire. Your response to the tickling is, of course, the output signal. The wee is the equivalent of the op amp going into saturation.
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Post by Luka »

:hihi:
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Post by andrewF »

defenestration wrote: what's the largest 'neural network' you've ever patched? even just two neurons feeding a third seems like it would be interesting. . . . or is it kind of a waste of time? I suppose it might depend on your perspective.
Most I have played with is 4, depends on what you like, but I had fun. It is useful to feedback the outputs to inputs of different neurons.
Just an example (the left sides of the boxes are inputs, right sides = outputs)
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Post by nathanxl »

andrewF wrote: ... Most of the tickling makes you giggle and squirm a bit, but every now and then your partner tickles a sensitive spot, like that little flap of skin between your testicles and your anus, then you lose it, jump in the air and a bit of wee comes out. This is the equivalent of the comparator kicking in, sending the output signal haywire. Your response to the tickling is, of course, the output signal. The wee is the equivalent of the op amp going into saturation.
:hihi: :hihi: :hihi:
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Post by ringstone »

4 PCBs for me please. That description was worth the money in itself :lol:

Cheers
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Post by cleaninglady »

nathanxl wrote:
andrewF wrote: ... Most of the tickling makes you giggle and squirm a bit, but every now and then your partner tickles a sensitive spot, like that little flap of skin between your testicles and your anus, then you lose it, jump in the air and a bit of wee comes out. This is the equivalent of the comparator kicking in, sending the output signal haywire. Your response to the tickling is, of course, the output signal. The wee is the equivalent of the op amp going into saturation.
:hihi: :hihi: :hihi:
signature of the year andrewF !! :hail: :hail: :hail:

I'll take two PCB's. Now i've got a month to stock up on old people wee underpants...
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Post by Pfurmel »

Andrew, you should become a lecturer, you have such a unique approach to describing electronic circuits.
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Post by aL Pariah »

I'd like 4 PCBs, please.
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Post by the bad producer »

I'll have 4 please!
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Post by Rod Serling Fan Club »

2 of each plz
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Post by frozenkore »

4 PCBs please
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Post by moogah »

4 seems like a good number.
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Post by fluxmonkey »

4 for me, por favor.

the only other reference i've seen to hardware neurons relative to electronic music is from Grant Richter: http://www.musicsynthesizer.com/Neurons/Neurons1.html ... are these similar, or different?
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Post by decaying.sine »

nathanxl wrote:
andrewF wrote: ... Most of the tickling makes you giggle and squirm a bit, but every now and then your partner tickles a sensitive spot, like that little flap of skin between your testicles and your anus, then you lose it, jump in the air and a bit of wee comes out. This is the equivalent of the comparator kicking in, sending the output signal haywire. Your response to the tickling is, of course, the output signal. The wee is the equivalent of the op amp going into saturation.
:hihi: :hihi: :hihi:
This taint enough information.
Brian
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"Vactrols ringing, Dude." "Thank you Donny"
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JJ
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Post by JJ »

Laughing my ass off here. Epical. :omg:
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Post by FetidEye »

2 for me !! :banana:
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Post by glitchpop »

These seem pretty interesting to me. I'll take two please. Maybe four if I get a new job. :hihi:
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Post by cyklopljud »

Two for me Andrew!
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