NLC Dispersion Delay - part two.

This is part 2 of the Dispersion delay.

Part one is here

 

 I first started building this in Feb , 2020.

Sorry for the delay. 2020 was a shit year.

Let hope '21 is better for everyone.

 

rECTIFIERS USED.

 

The official build guide & BOM is here

 

 This  is a bandpass filter module 

This module is based on ideas suggested by Lucas Abela.

The filters are in parallel and use vactrols to control delay (& I think cutoff frequency) ??

These are the light dependent resistors which I used.

GL5549

The type of LDR is impt.

It should have a dark resistance of at least 1M ohm.

I like a slow attack (or response time). 

VTL5C3s have a slope of 20, a dark resistance of 10M Ohms and a very slow response time.

  LDR type nr 5516.are good too.

 The 5516 gives about 50 Ohms at full brightness

 

 This module uses 9 vactrols.

You could just buy 9 of them from thonk or synthcube, but I decided to make my own.

In Andrews build notes he suggested red/green/orange/yellow LEDs

 

I chose orange for no better reason that I had a spare bag full of them that I probably wasn't going to need soon.

The colour of the LED will have a bearing on how the vactrol works.

So experimentation is in order.

 

I read somewhere, that yellow LEDs make the most efficient circuit.

 the best match is between green and green/yellow.  A blue LED is the worst possible choice.

Also remember that LED colours are normally not precise.

 

To get the best possible performance, the LED and LDR should have equal wavelengths.

This will require checking datasheets to find a good match. 

 

The yellow shrink wrap is to prevent shorts.

 

testing shrinkwrap first.

Double layer. 

You could use a white internal heatshrink to reflect as much light as possible back to the LDR

Of course if you have a 3D printer then make your own light tight boxes.

 

 

Im inserting the LED side in first.

remember that the short lead is the cathode. = K

 

These are the headers to join the 2 boards.

Jacks next.

All the pots are B100k

I'm surprised at just how well these vactrols work.

If anyone had tried making their own and experimented with different LEDs or LDRs do let me know.

Part one of the build is here

 

Links
+ NLC Wiki
+ NLC Build guide and BOM
+ NLC Blog (old)
+ NLC blog (new)
+ Blog re the delay
+ CMOS  info 
+ NLC DIY info
+ Nonlinearcircuits Builders Guild on FB
++ Integrated circuits - packaging 

+ Vactrols data sheet
  

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