madbeanpedals::forum

Projects => Tech Help - Projects Page => Topic started by: BassXtreme on December 09, 2010, 07:39:29 PM

Title: IC floating pins
Post by: BassXtreme on December 09, 2010, 07:39:29 PM
on IC3 pins 1, 5, & 8 are floating and not connected to anything? not to ground? I'm at this stage in the build and still learning  ;D
(http://i782.photobucket.com/albums/yy105/tallpall7/B2_layout.png)
Title: Re: IC floating pins
Post by: eniacmike on December 09, 2010, 10:21:50 PM
certainly looks like it. it's pretty common though. especially on cd4049 hex inverters when you are only using 2 stages. what circuit is this? did you check the schematic?
Title: Re: IC floating pins
Post by: CRBMoA on December 10, 2010, 12:03:54 AM
That is the Bloviator, and according to the schematic, those pins DO in fact float.
Title: Re: IC floating pins
Post by: madbean on December 10, 2010, 02:31:45 AM
In this case, IC3 is a TL071 is used as a regulator for Vb. In single op-amps, pins 1&8 are generally used for adding a small capacitor to limit slew rate. In this instance, however, the amp is used as a buffer to regulate the Vb voltage, so no cap is needed.
Title: Re: IC floating pins
Post by: asmiroth on November 15, 2011, 07:45:52 AM
hello i just wanna ask if are there any substitutes for TLO71? is LM741 ok for that? what are other replacements thanks.. i really want to make this pedal :)
Title: Re: IC floating pins
Post by: bigmufffuzzwizz on November 15, 2011, 08:15:11 PM
LM741 is a working alternative with the same pinout. Here's a few more;
http://www.diystompboxes.com/wiki/index.php?title=Main_Page#Pedal_designers_and_manufacturers