Author Topic: Question About Schematics  (Read 2127 times)

thetrend77

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Question About Schematics
« on: March 06, 2012, 03:58:28 PM »
Yesterday I bought everything I need to make my own breadboard prototyping rig. So I want to get a few schematics and possibly toy around with making my own circuit but I'm a bit of a noob when it comes to schematics. I'm not wanting to make a Timmy, but this schematic has the example I wanted to ask about.

http://www.madbeanpedals.com/forum/index.php?action=dlattach;topic=905.0;attach=2918;image

What is VB and how does the top part attach to the rest of the schematic?

This one also has the same type of disconnected part, but it says V+ and VR (whatever THAT means...): http://home.centurytel.net/flanneldrawers/mbb-sch-n.jpg

HALP MEH!

oldhousescott

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Re: Question About Schematics
« Reply #1 on: March 06, 2012, 04:43:34 PM »
Vb and Vr are bias voltage and reference voltage respectively, and are two names for the same thing, a voltage at or near the midpoint of the supply voltage, usually created at the junction of two resistors in series spanning the positive and negative supply terminals. This voltage becomes the virtual audio ground of the circuit, so the signal has room to swing both positive and negative.

Everywhere you see Vb (or Vr), you'll have to make a wired connection to another Vb, ultimately daisy-chaining back to the Vb near the supply source. It's just a short-cut way of showing where a common signal connects to various parts of a circuit without actually drawing the lines. This helps cut down the clutter on the drawing.

thetrend77

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Re: Question About Schematics
« Reply #2 on: March 06, 2012, 04:47:35 PM »
So basically they just connect to each other? Vb's to vb's, vr's to vr's, etc?

oldhousescott

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Re: Question About Schematics
« Reply #3 on: March 06, 2012, 05:19:33 PM »
Yes. If we didn't use signal node designations, we'd end up with drawings like this:

thetrend77

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Re: Question About Schematics
« Reply #4 on: March 06, 2012, 06:21:19 PM »
Got it! Thanks!