A friend, who is into guitars, asked me to build him a pedalboard PSU. I took it as a challenge, it is kind of out of my comfort zone 🙂 .
But he wants it to be made with isolated grounds on the channels. I kind of understand the concept - and why it is needed - , but have never seen such a device open or its schematic, so I don't know how to approach such project. Anbody?
The pieces in serial production are probably made with SMPS, but this is well beyond my time and knowledge (I think it would require extensive study and testing). So it would be more of a "classical" design with a big bulky mains TR, which is then rectified, filtered and regulated.
And there the question arises: should I use a separate TR secondary for every DC channel or is is it possible to have only one secondary, but then multiple bridge rectifiers attached to it? Does that give me the needed isolation? Could the noise "bleed through" the bridge? Should I expect trouble? Thanks ...
But he wants it to be made with isolated grounds on the channels. I kind of understand the concept - and why it is needed - , but have never seen such a device open or its schematic, so I don't know how to approach such project. Anbody?
The pieces in serial production are probably made with SMPS, but this is well beyond my time and knowledge (I think it would require extensive study and testing). So it would be more of a "classical" design with a big bulky mains TR, which is then rectified, filtered and regulated.
And there the question arises: should I use a separate TR secondary for every DC channel or is is it possible to have only one secondary, but then multiple bridge rectifiers attached to it? Does that give me the needed isolation? Could the noise "bleed through" the bridge? Should I expect trouble? Thanks ...
There are 3 ways of doing this. The first would be a transformer with multiple secondaries, one set for each power output. This requires a custom transformer though. Example: Misc >
The Ultimate Power Supply : DIY Fever – Building my own guitars, amps and pedals
The second would be a single transformer secondary, a single bridge, but separate voltage regulators for each output. The issue with this option is that all the outputs would share a single ground. Example: Build a Power Supply for Your Guitar Pedals : 7 Steps (with Pictures) - Instructables
Third, and pretty nuts, a transformer for each output 😀 http://geofex.com/article_folders/oldspyder/oldspyder.htm
The Ultimate Power Supply : DIY Fever – Building my own guitars, amps and pedals
The second would be a single transformer secondary, a single bridge, but separate voltage regulators for each output. The issue with this option is that all the outputs would share a single ground. Example: Build a Power Supply for Your Guitar Pedals : 7 Steps (with Pictures) - Instructables
Third, and pretty nuts, a transformer for each output 😀 http://geofex.com/article_folders/oldspyder/oldspyder.htm
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Thank you for a prompt answer!
I was thinking about the first way. Second is out of question, I need isolated grounds. The third one would be much too expensive and big, we are talking about 12 outputs ...
Custom TR for the first way is not a problem, there is a very affordable toroid producer in vicinity. But still: does every bridge need its own secondary?
And yet, if I decided to make a SMPS version, what should I do?
I was thinking about the first way. Second is out of question, I need isolated grounds. The third one would be much too expensive and big, we are talking about 12 outputs ...
Custom TR for the first way is not a problem, there is a very affordable toroid producer in vicinity. But still: does every bridge need its own secondary?
And yet, if I decided to make a SMPS version, what should I do?
For isolated grounds:
Each bridge rectifier must use an isolated secondary.
Each SMPS can have a non isolated output if it uses an isolated secondary.
Each SMPS must have an isolated output if sharing a single secondary.
Each bridge rectifier must use an isolated secondary.
Each SMPS can have a non isolated output if it uses an isolated secondary.
Each SMPS must have an isolated output if sharing a single secondary.
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A bunch of these could work: IRM-02-9
Or you could avoid working with mains voltage altogether and use a high-current laptop power supply feeding isolated DC-DC converters, such as this: IHL0215S09
Just check the current demands of the pedals your friend uses and select DC converters accordingly.
Or you could avoid working with mains voltage altogether and use a high-current laptop power supply feeding isolated DC-DC converters, such as this: IHL0215S09
Just check the current demands of the pedals your friend uses and select DC converters accordingly.
http://geofex.com/article_folders/oldspyder/oldspyder.htm
WPDLXFMR-2 Transformer
This made sense 20 years ago. Today you absolutely should just buy a One-Spot. The safety is built-in, and interfacing with funky pedals is mostly debugged.
WPDLXFMR-2 Transformer
This made sense 20 years ago. Today you absolutely should just buy a One-Spot. The safety is built-in, and interfacing with funky pedals is mostly debugged.