Rangemaster boost LED / on-off LED

[induction]

Just a bit of clarification (because the diagram is confusing, as you said): In practice, all voltages are relative. In other words, you can assign a value of 0V to anything, and all other voltages will shift accordingly. As long as your voltage measurements reference the same two points, the absolute voltages don't matter, only the difference between those two points (i.e. 0 and +9V is equivalent to +1000V and +1009V). However, in most cases, we do have a very specific reference voltage that everything in the circuit (guitar, pedals, amp) connects to: the 'true' ground of the power mains, which connects to all of the input/output jacks of the guitar, pedals, and amplifier). We must be very careful to make sure that these points have no significant voltage differences, or else very bad things can happen.

So to minimize confusion, in most cases it is  best to think of voltages in reference to the 'true' ground. Negative ground circuits use 0V as the negative rail and +9V as the positive rail. Positive ground circuits use 0V as the positive rail and -9V as the negative rail. Ground is 0V in either case. Both batteries and DC adapters provide voltage differences not absolute voltages. In other words, with a 9V battery or a 9V DC adapter, neither lead is connected to the ground or hot voltage of the mains (or anything else), so the absolute voltage is undetermined until you tie one of the leads to a known voltage. If you tie the negative lead to true ground (via the input and output jacks) then the positive lead becomes +9V. If you tie the positive lead to true ground, then the negative lead becomes -9V. This is why you can use the same 9V DC adapter for a negative ground circuit or a positive ground circuit (assuming you route the power correctly in the layout), but you can't use the same adapter to power both a positive ground circuit and a negative ground circuit at the same time via a daisy chain (unless you use a charge pump). If you did so, you would connect the positive lead to ground in the positive ground circuit, and the negative lead to ground in the negative ground circuit. These grounds would be shared between the two circuits via the guitar cable that connects them, so your adapter would attempt to maintain a 9V difference between its two leads while they are connected to each other. It would maintain this difference by generating as much current as it could, which still wouldn't be enough. A good power supply will have a mechanism to detect this and will simply shut down. A not so good adapter could simply burn up ('burn' as in actual smoke, flames, etc.).

All of these problems are easy to avoid if you reference your voltages to mains ground. Which is why I bring this up: The circuit diagram above shows the positive rail at +9V and the negative rail at -9V, which is incorrect and confusing, because it implies that you should use an 18V power source and tie the ground to a point halfway between them. This is called bipolar power, and is used by some circuits, but not this one (though it could be easily adapted). The rails should really be labelled 0V and -9V. The zero tells you where to find the ground that you attach to the case and the input/output jacks.

[MariaOrsic]

Hi Induction
Thanks for taking the time to post such a comprehensive reply, however I am now totally confused! ( apologies but i have virtually zero experience as yet).

Would it be possible to create me a schematic suitable for dummies?

Thank you so much in advance?

[seedlings]

Hi Induction
Thanks for taking the time to post such a comprehensive reply, however I am now totally confused! ( apologies but i have virtually zero experience as yet).

Would it be possible to create me a schematic suitable for dummies?

Thank you so much in advance?

The original Fuzz Face circuits use PNP transistors.  Many circuits now use NPN transistors.  The current flows differently through them, and a PNP device can be thought of as requiring a 'positive ground', while a NPN device requires a negative ground.  It just so happens that the circuit you chose to build requires a positive ground because those are PNP transistors.  That is all.

As induction alluded to, ground is ground is zero (0 volts).  So another way of looking at it, is that your NPN transistors have a 0V ground and a -9V positive, but either way there is a 9V difference potential (which is why induction added 1000V, to illustrated that it's the difference between them that we care about).

So, if you were to build the exact same circuit with NPN devices, it would make sense much faster, because we're used to 0V being ground and +V being positive.  Here is the difference between PNP and NPN (if I didn't mess up the diagram).



I will add that at some point in our effect building hobby careers, we all have to 'hit the books' to get enough of an understanding to continue on. Nowadays, it's just a matter of watching videos on youtube!

CHAD

[induction]

Hi Induction
Thanks for taking the time to post such a comprehensive reply, however I am now totally confused! ( apologies but i have virtually zero experience as yet).

Would it be possible to create me a schematic suitable for dummies?

Thank you so much in advance?

Here's a schematic:


For future reference, the image you linked to before was a layout, not a schematic. Layouts are useful for telling you how to build a circuit paint-by-numbers style. To understand how a circuit works (or to make your own layout) a schematic is indispensable.