Author Topic: Help with Honey Bee Circuit  (Read 286 times)

spi

Help with Honey Bee Circuit
« on: September 19, 2020, 04:16:21 PM »
Hi,
I'm in the process of building a Honey Bee.  I was planning on using the component values that I've seen on the original BFJE versions of the circuit.

I bought the guitarPCB Killer Bee PCB to use for this project, which has pretty much the same circuit but with some different values.  While figuring out what components to swap, I happened to notice one slight difference in the circuit.

Here's how I see most HBs (including madbeans and aion projects) laid out:



Here's how the Killer Bee is laid out:



Notice the difference in R7?  In the first circuit, the signal goes to both R7 and R9.  In the second circuit it goes through R7 to get to R9.

I was thinking that if I wanted to make the circuits equivalent, I could use a value of 20K for R9 so that signal passing to C6 sees a resistance of (27K and 20K = 47K).   



But I'm not sure that this has unintended consequences (for example changing the RC filters of R7/C7 or R9/C6).  Or maybe I'm overthinking it and I can follow either schematic and it won't make much difference.

Can anybody whose electronics are less rusty help me out here?

« Last Edit: September 19, 2020, 04:18:55 PM by spi »

antonis

Re: Help with Honey Bee Circuit
« Reply #1 on: September 19, 2020, 06:04:20 PM »
In theory, you're right..  :icon_wink:

But, it should stand only in case of both RC combinations items values are way far apart..
(e.g. R7 > 100XR9 & C7 > 100XC8 ..)

As they are in Killer Bee, R9/C6/R8 are part of C7 section (are set in parallel with C7) so an "equivalence" of both circuits should need some kind of  transfer function analysis..
(Bode plots synthesis for each single RC pole..)

P.S.
Better implement your initial idea and tweak a bit 20k value..
« Last Edit: September 20, 2020, 04:02:23 AM by antonis »
"I'm getting older while being taught all the time" Solon the Athenian..
"I don't mind  being taught all the time but I do mind a lot getting old" Antonis the Thessalonian..

spi

Re: Help with Honey Bee Circuit
« Reply #2 on: September 24, 2020, 01:27:20 PM »
Thanks, good idea to try a plot.  I modeled that network and ran a frequency domain analysis.  My free trial of circuit lab ran out before I could tweak the sweep to just the audio range, so it's not ideal, but at least I have an idea what it might look like.

Honey Bee:



Killer Bee:



Killer Bee with my mod:



My mod doesn't seem to have its intended effect, as the curve didn't change much.