[SOLVED] power supply -48 vdc

[foxbrain]

hi
how can i make a power supply that gives -48 vdc ? i need it to supply AG1110.
thanks

 

[rfredel]

Hello foxbrain,

here you have a schematic of power supply.



If you need an other line voltage, only take a transformer with your line voltage


Regards

Rainer

 

[BradtheRad]

AG1110... If this IC is to be used in a telephone system, then the incoming telephone line is at -48V (more or less) relative to earth ground.

However if it is not present, then you can obtain it by chopping a DC supply into pulses, and feed that to a voltage multiplier.

Or use a boost converter. Etc.

 

[foxbrain]

However if it is not present, then you can obtain it by chopping a DC supply into pulses, and feed that to a voltage multiplier.
Or use a boost converter. Etc.

what do u mean by it ? and how can i make it?
the voltage from the phone line changes when it rings and when someone is talking..... isn't that right?

 

[BradtheRad]

what do u mean by it ? and how can i make it?
the voltage from the phone line changes when it rings and when someone is talking..... isn't that right?

The phone line has -48 V on it when there is no activity. It could be as much as -60V amplitude (or greater).

When the phone is ringing, I believe it has 90 VAC coming into the phone.

When the phone is off the hook, you will measure much lower amplitude than -48V.

This means you cannot power the IC from the phone line during those times.

So it's likely you will need to obtain (or construct) a power supply which draws from house current, as Rfredel recommends (post #2).

The methods I spoke of are difficult.

 

[foxbrain]

isn't there an error in the schematic in post #2?
the output of 7924 should give -24 not -48? isn't that write?

 

[rfredel]

Hello foxbrain,

in this schmatic you see the Z-diode in the ground connection of 7924. So you set the regulator ground to -24V. In addition to the output will be -48V.

Its a circuit to make the fix voltage higher then without Z-diode.

Regards

Rainer

 

[foxbrain]

that's great.....
thanks

 

[Aalia Nebhan]

Nicely presented information in this forum, I prefer to read this kind of stuff.

The quality of content is fine and the conclusion is good.

Thanks for the post.


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