Yellow Humper Schematic Needed

[Torchy]

crp

[Torchy]

crp

[MartyMart]

No go ! just did a huge google search and went through all the sites I know of........nothing !
Purple and green would be nice ?
Enjoying the orange "very-much" was just offered £80 for it !!!   well it is an original case ....... ( I'm keeping it ! )

anyone ?

sorry,
Marty.

[RLBJR65]

Couple of years ago I too was on a mission to find all those schems. I could never find the Yellow Humper schem. There seems to be even less info out there now than there was back then  

My understanding is that it was similar to the Purple Peaker, but freq. were peaked higher or lower. (can't remember which) The PP was a whole lot more popular, which makes the Humper rare.

Good luck in your search! If you find it I would still like to add it to my collection of schems.

[B Tremblay]

The Yellow Humper was a simple EQ circuit, like the Purple Peaker, but tuned for a bass guitar.

The very first step is to increase the input cap.  Then, we can probably lose the parallel cap/resistor high-pass filter.  The twin-t filters are quite easily tuned to different frequencies.  The only obstacle is being restricted to standard cap and resistor values.

For example, I tuned the Purple Peaker's LO filter to 159Hz, which is close to the 12th fret of the low E string.  For a bass, we could drop it down an octave.

Here's the PP page:
http://home-wrecker.com/peaker.html

To do this, the 100k resistors are changed to 82k and the 51k resistors with 39k.  The .022uF cap is changed to .047uF and the two .01uF caps are each replaced with .022uF caps.

We use the standard formula f=1/(2πRC) with R=82k and C=.022uF
That gives us a notch frequency of 87hz, which is right around the 13th fret of the E string of the bass.

For the HI filter, we could shoot for a filter frequency that is half of the PP version.

We'll still use 82k and 39k resistors in place of the 100k and 51k, respectively.  Next we substitute .0015uF and .0033uF for the 500pF and .001uF caps, respectively.

So with R=82k and C=.0015uF, the filter is tuned to 1.29kHz.  Not exactly half, but decent enough.

Here's an untested schematic that should be a good starting point:


RG's Technology of Wahs article has good twin-t info.  There are posts in the archives of this forum that are helpful as well.  Search for "Purple Peaker."

[R.G.]

Notice that an integrated opamp with a couple of bits of housekeeping would replace the transistors just dandy.

[Torchy]

crp

[B Tremblay]

Please let me know if you try the "Yellow Stumper."  My breadboards are full with other projects at the moment.

[puretube]

frequency response diagrams here:
http://homepage3.nifty.com/ichian/analog/spectrum/boost_freq3.htm
maybe a schem is hidden there, too?

[Torchy]

crp