madbeanpedals::forum

General => Open Discussion => Topic started by: madbean on October 30, 2014, 11:47:11 PM

Title: Something is not quite right here...
Post by: madbean on October 30, 2014, 11:47:11 PM
I can't put my finger on it though....hmm.

So nice to find these things AFTER you build them.
Title: Re: Something is not quite right here...
Post by: wgc on October 31, 2014, 01:44:58 AM
I love finding them right after notice comes that the pcb shipped
Title: Re: Something is not quite right here...
Post by: jimilee on October 31, 2014, 01:53:42 AM
Man, I wish I knew what I was looking at, it's gotta be funny, i just  know it...you design them, I'll just keep building them...:-p
Title: Re: Something is not quite right here...
Post by: rullywowr on October 31, 2014, 05:00:07 AM
Nothin like putting the source for VB outside of the voltage divider. Shows that Bean is human like the rest of us after all ;)
Title: Re: Something is not quite right here...
Post by: alanp on October 31, 2014, 06:21:57 AM
Not quite -- if I'm understanding this rightly, +9V should be where VB is, and VB (along with the smoothing cap) should be where the right angle join between the two 100k resistors is.

Or I could be completely talking out my ass.
Title: Re: Something is not quite right here...
Post by: selfdestroyer on October 31, 2014, 07:27:34 AM
Quote from: jimilee on October 31, 2014, 01:53:42 AM
Man, I wish I knew what I was looking at, it's gotta be funny, i just  know it...you design them, I'll just keep building them...:-p

i'm with you Jimi.. glad I'm not alone.

Cody
Title: Re: Something is not quite right here...
Post by: rullywowr on October 31, 2014, 07:30:22 AM

Quote from: alanp on October 31, 2014, 06:21:57 AM
Not quite -- if I'm understanding this rightly, +9V should be where VB is, and VB (along with the smoothing cap) should be where the right angle join between the two 100k resistors is.

Or I could be completely talking out my ass.

That's exactly correct.
Title: Re: Something is not quite right here...
Post by: Justus on October 31, 2014, 02:10:44 PM
Quote from: jimileeMan, I wish I knew what I was looking at, it's gotta be funny, i just  know it...you design them, I'll just keep building them...:-p
Quote from: rullywowrNothin like putting the source for VB outside of the voltage divider. Shows that Bean is human like the rest of us after all ;)
Quote from: alanpNot quite -- if I'm understanding this rightly, +9V should be where VB is, and VB (along with the smoothing cap) should be where the right angle join between the two 100k resistors is.
Quote from: selfdestroyeri'm with you Jimi.. glad I'm not alone.

Uh...  I'm with Jimi & Cody.  What's VB?  lol
Title: Re: Something is not quite right here...
Post by: muddyfox on October 31, 2014, 02:15:28 PM
It's a bias voltage, created by halving the input voltage (9V) by a voltage divider formed by two equal resistors.

It is commonly used to bias an opamp so the output can go equally far below and above the 4.5V rail.
Title: Re: Something is not quite right here...
Post by: wgc on October 31, 2014, 06:58:08 PM
Quote from: alanp on October 31, 2014, 06:21:57 AM
Not quite -- if I'm understanding this rightly, +9V should be where VB is, and VB (along with the smoothing cap) should be where the right angle join between the two 100k resistors is.

Or I could be completely talking out my ass.

This is how I interpreted it.  I made the same mistake on a dirt pcb I did recently.  Take two in the works.
Title: Re: Something is not quite right here...
Post by: the3secondrule on November 01, 2014, 02:36:15 AM
Quote from: Justus on October 31, 2014, 02:10:44 PM

Uh...  I'm with Jimi & Cody.  What's VB?  lol

pretty sure this is what you guys are talking about, right?
http://en.wikipedia.org/wiki/Victoria_Bitter (http://en.wikipedia.org/wiki/Victoria_Bitter)
Title: Re: Something is not quite right here...
Post by: TGP39 on November 01, 2014, 03:27:44 AM
I actually think this is a great idea. Maybe show a little snippet of a circuit and talk about what's right, what's wrong and how to improve it.  Let's call it Circuit of Fifths. I know I learned something very important from just this little post by Brian.