I'm going to start by saying that I am very new to this...That being said, I have been reading up on power supplies and wanted to know if this would work to make a +-30 volt power supply? I have 2, 30vdc power supplies and wanted to use them to power a phono preamplifier. I've seen schematics of +-9 volt power supplies using 2, 9 volt batteries and was curious if this would work. Any thoughts or suggestions would be greatly appreciated.
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Yes, if there is a third "ground" post, in addition to the + and - DC outputs, the supply is likely to be isolated.
You can also use an Ohmmeter between the negative and ground to see if there is a direct connection.
If not, you can series them.
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Thank you for the quick responses. The power supplies are isolated (lowest continuity between the plug and the output is about 1M ohm) and they are each rated at 12va. If 4x10,000uf is to much capacitance, how would I know? I was planning on using the 10,000uf capacitors because I have them lying around. I am also considering adding 2 4.7uf film bypass caps after.
Save them and use them later for some purpose where they will be more useful.madskaman said:
You can't necessarily improve a supply just by slapping on a big cap. If the PSU is noisy then you need a filter (e.g. CR), not just a cap. If it is not noisy then you don't need to add anything.
Why?
By carefully studying the PSU datasheet and/or circuit or by doing careful measurements. Regulated PSUs can have an inductive output impedance so adding caps can lead to more noise and the risk of instability.
Don't just copy what you have seen other people do. They probably don't know what they are doing, and are just copying someone else too.
You could "improve" your proposal by adding some resistance,
Looking at the +ve supply rail (RED)
Add a 1r0 metal film 600mW resistor between source power and first capacitor.
Add a 1r0 metal film 600mW resistor between the first capacitor and the second capacitor
Add a 1r0 metal film 600mW resistor between the second capacitor and the local decoupling on your phono PCB.
Now repeat the 3 added resistors for the -ve (BLACK) supply rail.
These six resistances add 3pole passive filters, that help attenuate all the interference that tries to enter from the mains supply and from the wiring leading up to your PSU.
Looking at the +ve supply rail (RED)
Add a 1r0 metal film 600mW resistor between source power and first capacitor.
Add a 1r0 metal film 600mW resistor between the first capacitor and the second capacitor
Add a 1r0 metal film 600mW resistor between the second capacitor and the local decoupling on your phono PCB.
Now repeat the 3 added resistors for the -ve (BLACK) supply rail.
These six resistances add 3pole passive filters, that help attenuate all the interference that tries to enter from the mains supply and from the wiring leading up to your PSU.
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