Hi All,
i need to inject 48vdc into a channel strip and it needs to come from a 18-0-18 ac transformer. I will only need to power one mic. Ill be building my own so i need a schematic....any suggestions. The mic ill be using says 8ma minimum draw.
Thx
i need to inject 48vdc into a channel strip and it needs to come from a 18-0-18 ac transformer. I will only need to power one mic. Ill be building my own so i need a schematic....any suggestions. The mic ill be using says 8ma minimum draw.
Thx
Are you saying you need +48Vdc from a transformer with 18-0-18 Vac output?
If that is so, connect 18-18 (ignore the “0” on the transformer) to a full wave bridge rectifier and capacitors and you will get +50Vdc . Thereafter you can connect it to a +48 Vdc voltage regulator to get your +48Vdc.
If that is so, connect 18-18 (ignore the “0” on the transformer) to a full wave bridge rectifier and capacitors and you will get +50Vdc . Thereafter you can connect it to a +48 Vdc voltage regulator to get your +48Vdc.
18 V is a bit tight, but it will probably work, especially when you have a transformer with a relatively large ratio between the unloaded and loaded voltages that you don't fully load.
I would use an LM317HV so it doesn't blow up if the output should get shorted.
I would use an LM317HV so it doesn't blow up if the output should get shorted.
Would you consider using less than 48V? It's the standard but it's seldom actually needed.
Some 15 years ago, I made a phantom PS for a church that was using an old mixer that came without a phantom supply. I live in a remote part of a third world and often have trouble sourcing the parts I need. So I designed and built a 36V supply which is still being used today.
I could whip up something similar for you if you're interested. It won't be identical to the one I built since I had to use a 12-0-12V transformer.
Some 15 years ago, I made a phantom PS for a church that was using an old mixer that came without a phantom supply. I live in a remote part of a third world and often have trouble sourcing the parts I need. So I designed and built a 36V supply which is still being used today.
I could whip up something similar for you if you're interested. It won't be identical to the one I built since I had to use a 12-0-12V transformer.
That's not suitable for a 48V output with an 18-0-18V transformer. Not enough headroom for proper regulation. It will work for a lower output voltage. It's similar to the circuit I had in mind.
But you'll have to clarify if the same transformer is also used for another circuit with the center tap grounded. That makes a difference whether C3 and C4 are necessary.
You will be fine 40V, even less for phantom. I often use 30V when testing repairs. The 48V harks back to the days when broadcast stations had a 50V battery supply that was used for remote switching and phantom power.