[sdiy] Flanger???

[Gene Stopp]

Hi John,

I suspect you're right - I suspect what I'm dealing with is amp clipping
rather than triangle wave direction reversal stressing the amp output
structure. I do remember that 120 VAC is something like 170V P-P on a scope
(is that right?). Therefore my 33 VAC needs 46V P-P on the scope, right?
Should be well within the power rails of the amp running complimentary
outputs (assume +/-40VDC). However there will be drops, as the output
push-pull transistor junction goes thru a power resistor to the output
terminal. Maybe I am hitting the rails more than I think.

The harmonic series for a triangle is harmonic amplitude = 1 over the
harmonic number squared, odd only, right?

I think I forgot to mention that I "heard" the failure when it happened. It
was kind of a little buzzy zappy sound coming from the transformer when I
turned up the frequency, at least I think it was the transformer - I dunno,
I'm used to sound coming from speakers.... Perhaps the transformer changed
impedance when I deviated from 50-60 hertz, and this caused excessive
clipping. I didn't watch the scope at the time frankly, I was watching the
incandescent bulb to see how it liked the higher frequency. When it went
out, I reactively pulled the plug.

How close is a power transformer "tuned" to the intended mains frequency?
I've never played with aircraft parts. Would the impedance go up, or down
with frequency? I would think that it starts out very low (almost dead short
at zero hertz) and goes up from there, but does it go back down again?

Best Regards,

- Gene

-----Original Message-----
From: John L Marshall [mailto:john.l.marshall at gte.net]
Sent: Friday, June 28, 2002 4:48 PM
To: Gene Stopp; synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] Flanger???


Gene,

The harmonic distortion from a triangle wave should not be a concern. The
third harmonic is 1/9 amplitude of the fundamental.

But, the amplifier must be capable supplying peak voltage which will be some
factor above the RMS voltage, for sine waves that will be square root of
two.

Have you ever looked the waveform of those cheapie voltage inverters that
plug into the cigar lighter? Rectangular waves with dead zone. No similarity
to a sine wave, yet most electronics, including transformers and motors work
without complaining.

Take care,
John