Spice modelling some noise generation circuits.
To minimize cost, this time I have decided to etch several boards at once. I can score the board with a razor knife before I begin the solder phase. The circuit traces are from the YuSynth site. The Sample N Hold/Noise module can be divided into two separate boards. I have found this very helpful and convenient.
A bath in liquid tin solution turns the board from copper to silver hue. This isn't necessary, in that solder will eventually cover every trace on this board.
Using a diamond carbide drill bit, I drill all the holes for components to drop into. Lots of holes to drill. The diamond carbide tip drill bits work better than the Dremil tool bits and they don't break as easily.
Device under test. This module worked perfectly right off of the bench. I love it when that happens. There is pink and white noise produced and a third random output which can be used as a random LFO or as intended. The intent is to patch the random into the frequency modulation input of a filter and allow it to sweep the frequency in a random fashion. This produces the sound one might hear if they were camping atop Mt. Everest during a wintry windstorm. Very space age, dare I say, new age goodness for sound design synthesis!
In order to select a transistor with the whitest noise spectrum, I decided to install a 3-pin female header, so I can try out various transistors before I commit to a final selection. When I mount the pcb into an enclosure, I'll remove the header and simply solder the transistor into place.
There's a lot of unused panel space on my .com Ring Modular Module. I'm going to install my noise board in this open real estate.
Removing the Ring Mod PCB from the standoffs.
There's only three jacks on the Ring Mod, but I will label them just so everything goes back together without any second guessing....
PCB removed. The standoffs also need to be removed as well, in that the ones I have are 1/4" longer.
Here you can see the open area to work with. I am adding two additional holes for the Noise PCB to mount just below the Ring Mod PCB. I will use washers and share the two middle standoffs between the two boards. I must be careful to avoid any shorting between the two boards.
Three simple holes at the drill press for the three noise output jacks. Pink/White/Random(LFO).
I have removed the 3 pin header and have installed the BC547 xtor in place. As mentioned on a previous slide, this transistor has been selected to provided the whitest noise spectrum.
Side View. Everything fits back together nice and snug. Don't forget the cable ties.
Alternate view.
Alternate view.... .....
View of other side.
Looking good!
I just need to find the label maker and label the jacks.
Jacks are labelled.
Safe and sound, back in the modular case. Now it's time for some arctic breeze......
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Noise Generator - Module
The noise generator generates three different signals : white noise (evenly distributed frequency spectrum), pink noise (1/f frequency spectrum, that is with a 3dB/octave slope), and a slow varying random voltage (frequency smaller than 6Hz).
