day two of electronics playing 20:23 (2006.08.01:1 research#34 tech_notes#170)


1) avalanche transistor noise:

success with 2n3904s (NPN) as per:


but should do more with either extra 2n3904 as amp:

see: http://willware.net:8080/hw-rng.html

or using 74LS04 (biased by 2.7k resistor across I/O to bias into "linear region" where they act as op-amps

white noise: very quiet

2) modified simple 40106 (Hex inverting Schmitt trigger) acting as


a) standard configuration is

|      |
|  |\  |
-1-| >-|-2-> next stage
|  |/

Frequency dependent on R and VR and capacitor (higher uF, lower freq)

b) first step is inserting feedback transistor-based VR between 1 and 2

c) also VR between inputs of successive gates 3 to 1

d) untying capacitors to ground and put LED in transistor circuit

e) connect one of capacitor ends to wire ariel - radio and electromagnetic sensitivity - this will be fence/radio/street performance module:

outline all modules to be made with PCBs

f) used Darlington pair to amplify signal for small speaker

research ideas:

1) input to 40106 circuit and how we can further effect from outside.

2) place 40106 gates in a loop

3) amplify transitor noise from avalanche