The Elliot P05 can make +/-15vdc from a single 16VAC transformer. I’d suggest using the 16VAC wall wart as others have mentioned.
In this specific application for Pearl 3, because Pearl will have 15vdc on it’s inputs, the Pearl’s onboard regulators will need to be replaced with 7812/7912, preferably the OnSemi MC7812/MC7912.
In this specific application for Pearl 3, because Pearl will have 15vdc on it’s inputs, the Pearl’s onboard regulators will need to be replaced with 7812/7912, preferably the OnSemi MC7812/MC7912.
Switching wall warts can work if they have a 3-prong plug, ie a safety ground pin. If they only have two pins then you get ground current noise on the output ground and half the AC line voltage wrt earth ground. This is because the input filter Y-cap is connected to the output instead of the safety ground.
You probably don't need any kind of regulator. An RC filter should be enough, ie Rs on both sides. Think of it as a balanced circuit and understand that "ground" is rarely zero volts. Using the same "ground" as a return for everything is a recipe for noise and other problems.
You can use an op-amp to generate a half voltage reference but usually it's fine to just use a divider instead of a single resistor as a ground reference and separate the bias reference(s) from the output ground. IE use a pair of caps across the single supply as output ground instead of a DC blocking cap on the output. On the other hand, if your wall wart connects one side of the output to safety ground, then you can't float the DC output.
When I was young, a handy source of transformers suitable for this sort of thing was doorbell or HVAC transformers. There was no internet, and no local electronics supply houses. I used a bell transformer, bridge, cap, pot and a germanium Darlington for a 0-15VDC supply as my bench supply, except I didn't have a bench.
You probably don't need any kind of regulator. An RC filter should be enough, ie Rs on both sides. Think of it as a balanced circuit and understand that "ground" is rarely zero volts. Using the same "ground" as a return for everything is a recipe for noise and other problems.
You can use an op-amp to generate a half voltage reference but usually it's fine to just use a divider instead of a single resistor as a ground reference and separate the bias reference(s) from the output ground. IE use a pair of caps across the single supply as output ground instead of a DC blocking cap on the output. On the other hand, if your wall wart connects one side of the output to safety ground, then you can't float the DC output.
When I was young, a handy source of transformers suitable for this sort of thing was doorbell or HVAC transformers. There was no internet, and no local electronics supply houses. I used a bell transformer, bridge, cap, pot and a germanium Darlington for a 0-15VDC supply as my bench supply, except I didn't have a bench.
Yes, the wall wart or single winding transformer still supports +/- 15V output. This mode is called half-wave rectification. The positive half-wave goes down one path of the bridge rectifier and the negative half-wave goes down the other path. The current available to the preamp will be less than a full-wave configuration, but more than adequate.
Rob