Some excellent answers here in this thread - I’ve not much to add, except one bit of potentially useful information for people building 9v FX pedals:
9v pedals are normally designed to work with 9v supplies and/or 9v batteries. Battery voltages are notional, the voltage gradually drops but the circuit still works for a long time.
This means that the power voltage is usually not critical! The FX may work down to 6v or so before performance deteriorates, depending on the design.
Great point Don. Some diehard tone nuts only run pedals from batteries that have been used because they believe the tone to be better with a lil less
Given that many classic guitar pedals are just one to three transistor discrete designs, running them in lower voltages can affect their performance in a very noticeable way.
Operating FX at lower voltages is likely to gradually introduce non-linear distortion.
For those wanting to experiment with different supply voltages, there are alternatives to the 7809 9v regulator, such as the 7808, 7807 and 7806.
There is also the adjustable LM317 regulator, which uses a slightly different circuit, which can easily be found online.
Some FX can also be run at higher voltages, but don’t try it unless you know what you are doing - damage may result.
