[sdiy] Re: Neon Oscillators

[Scott Gravenhorst]

I did this as a kid.  All you do is put a cap across the lamp
(with the standard current limiting resistor) and it
oscillates.  The first resistor is for max current limiting
and should be at least as large as the value used to simply
turn on the bulb.  Making the variable resistor larger will
cause the frequency to lower.

                          +------+       +---------> OUTPUT
                          |      V       |
   +V (100?) ----/\/\/\/--+--/\/\/\/\/---+---BULB----+
                                         |           |
           MAX CUR. LIMIT       VAR      +----||-----+      
      
                                                     |
                                                    ---
                                                    GND

The power supply needs to be something more than the
threshold of the bulb.  I used an NE-2 which turns on at
about 65 volts.  Because of this, the variable resistance
should not be touched by a human.  I don't remember the cap
value, but .01uF comes to mind.  I also do not remember what
the ouput swing is, but it does not go all the way to ground.
 A series coupling cap is probably a good idea.  I think the
max current limiting resistor is around 270 K.  Also, outside
influences can easily affect the threshold and therefore the
oscillator's frequency.  Even light will affect it. 
Temperature?  I dunno.  Some neons are stabilized (within
limits) with a tiny spec of radioactive material inside the bulb.

Hope that helps.

"M. Turner" <electronophus at yahoo.com> wrote:
>Does anyone have a schematic for a neon relaxation
>oscillator that would be appropriate for freqency
>control via something like a resistive wire (ala the
>trautonium)?
>
>thank you
>Marc

=========================================================  
- What good are laws that only lawyers understand?
- Government: The other religion.
- The media's credibility should always be questioned.
- Lambs who lie down with lions are lunch.

-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
-- Linux Rex         | RedWebMail by RedStarWare
-- FatMan: home1.GTE.NET/res0658s/FatMan/
-- NonFatMan: home1.GTE.NET/res0658s/electronics/