Phantom PCB

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delphi said:
Just read this thread and it looks like I am too late. Count me in for 4/6 if you do a second run please.

Probably a stupid question, but I recollect the regulation requires a minimum load of 15ma - so I assume this is taken into account with your output loading ??

The data sheet does indeed recommend 15mA minimum and sets the value of the resistor across the 1.25V reference to ensure this. It does however mean over 700mW of heat dissipated in the lower leg of the pot divider (which is why the layout allows space for a 2 watt resistor). To help even more I usually tweak this resistor to set the correct output voltage and I do this by using a pair off 2watt similar valued resistors in series which further reduces the dissipation in each one.

That said, the TL783 data sheet shows you only need 8 mA standing current to maintain regulation at an input voltage of 70V so I usually set the resistor across the 1.25V reference to 120 ohms (see PCB) which ensures a 10mA minimum.

Cheers

Ian
 
Marcocet said:
Me too. Looks like I missed this run but I'm in for 6 boards if you do another. Thanks!

I had not expected the board to be this popular. It looks like there's a strong possibility of a second run.

Cheers

Ian
 
ruffrecords said:
I just finished a layout for a basic +48V phantom PSU that I have built on tag strips in the past. Nothing magic, just 50V ac input to four diodes, 4700uF 100V smoothing, TL783 reg with holes for heatsink, output setting resistors and output cap plus half a dozen mounting holes. Size 4 inches by 2.2 inches.

I am going to have some made and wondered if anyone else was interested in one before I place the order. Cost will of course depend on how many I order but at 20-off it is looking like 8 GBP delivered and for 100-off about half that.

Cheers

Ian

30 PCBs arrived in the post this morning. I am going to build one up to make sure it is OK. In the meantime I will PM all those who expressed an interest for delivery and payment info.

Cheers

Ian
 
I have built up the PCB and tested it and it works fine so I am happy to take orders. I'll PM all those who originally asked first.


phantomPCB.JPG



Cheers

Ian
 
r2d2 said:
So cool !
how many 48v mics can fed ?

Depends on the size of heat sink. With the 2inch one shown in the PIC it should easily source 150mA. Most mics take less than 5mA form the phantom supply so on that basis it should be able to supply as many as 30 mics. If you just want to power a couple then you can probably do without the heat sink.

can be used with old neve style preamp?

If you mean the transformer input type then the answer is yes.

Cheers

Ian
 
I will be posting orders to the following group members on Monday:

helterskelter
kazper
guy_4
mamati

Everyone else has been PM'd so please send in your payments.

Cheers

Ian
 
The gods were against me today and I did not manage to get to the post officve in time. The good news is I now have SIX parcels ready tp go first thing tomorrow (Tuesday) to:

helterskelter
kazper
kooma
peps
guy_4
mamati

Cheers

Ian
 
ruffrecords said:
The good news is I now have SIX parcels ready tp go first thing tomorrow (Tuesday) to:

helterskelter
kazper
kooma
peps
guy_4
mamati

Just got back from the post office - six parcels on their way.

Cheers

Ian
 
Hi Ian. It was an intermittent paypal error - once I got home from vacation, all went smooth.

Cheers!
 
For some reason my PCB supplier sent be 6 extra PCBs so I have sent PMs offering these to those who missed the first round but expressed an interest. So check your PMs guys!

Cheers

Ian
 
okgb please clear your PM box. You are right at the top of the list but I cannot contact you because your PM box is full!!!


Cheers

Ian
 

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