[Noisebridge-discuss] [dorkbotsf-blabber] Dynamo Regulator Help Needed

[gaspo lists]

On Jul 21, 2013, at 17:51 , Johny Radio wrote:

> On 7/21/2013 1:04 PM, gaspo lists wrote:
>> you get better "sound" from a speaker driven with a square or sawtooth wave than with a sine wave.
> 
> sine is the wave i seek, not square or saw. I'm quite familiar with all of them, from producting electronic music. 

ok, then you got understand, prob better than me :)

> 
>> sine waves "heave" as you say, not very loud, but nice soft sound.
> 
> i mean a kind of slow-motion heaving, below 1 hz. 

see the dbot post about using a capacitor in series
to eliminate the larger DC component.

hook black of motor to shield of amp input,
and hook red of motor to a capacitor,
the other lead of the capacitor goes to the center of the input.
so the motor is "in series with the capacitor to the amp".

i'd start with a .1uf or 1uf and work up from there.
smaller uf will give you higher frequencies.
bigger will give you lower and block the higher.

still can blow amp or amp input tho if V from motor is high enough.

> 
>> so if youre just tryin to get speed-of-crank to audio-out,
>> a diode or bridge pair of diodes to limit the output
>> to a half-wave-DC will be nicer to the amp.
>> 
> 
> will try this, even tho it won't give me sine. short-term solution :(

but it should be "half sine", ie, still "curved" shaped,
just at double the frequency and not "reversing"....

> 
>> (amp prob does not like reverse current)
> 
> please explain

if the signal (center pin) on the amp goes _below_
the shield (outside ring) in voltage, that's "reverse".
ie, the center should always be > 0 V WRT to the shield.
theory is you're now "pulling" instead of "pushing"
(or the other way around if you are a "holes" believer).

connecting a diode between the center and shield
with the "arrow" of the diode pointing to center,
will shunt all "reverse" currents thru the diode.


> 
>> can only imagine what you're tryin to do there.....
>> 
> 
> make noise :)

right!

then you might want to consider using transformers too.
wind a small coil of copper wire,
connect the motor output into the coil.
wind another coil that is connected to the amp input.
put the two coils near each other,
try a nail or bolt in their centers, etc.
early guitar effects pedals did mechanical ways
to put coils near/far each other to make distinct sounds.
good way to "couple" circuits without them really "touching".

have fun!

--gaspo.