Just THAT - preamp (Pre Grinder)

I think we are doing the same... is kicad or eagle? I can send you mine on kicad if you want

Cosmonaut said:

I think we are doing the same... is kicad or eagle? I can send you mine on kicad if you want

Click to expand...

Thanks for offering to share, but I only need to go through the silk screen and punched in values a few times before I'm ready to try the layout I have.

Gustav

This seems to be much more complex, I was only doing a new design with the same circuit, just putting everything in a smaller pcb, will wait for your pcb's!

Great work!

Just had a quick read through this design, and I can see one problem with it.
In case of a phantom fault (shorted cable, hotplugging, etc), there will be a 48v spike on the power rails.
That could kill all the chips on the board, including the regulators in the supply.
The supply rails need enough capacitance (several times the input caps) on the power rails, to dump the spike in.
And 18v TVS diodes (e.g. P6KE18).
If there is enough capacitance on the 15v rails in the supply, adding two TVS' might be enough.
All of this is explained in the THAT phantom protection datasheets.
Better be safe than sorry.
Leo..

Crap, I just ordered 4 of these. As a newbie, what should I do to avoid the scenario stated above?

just use a decent powersupply - something like 1000uF's on the secondary side of the +/-V regulators.

Or add two 1000uF/25V to the board - one between +V and 0, another between -V and 0.

Jakob E.

Cool. Thanks for the tip!

Some rail capacitance is good.
As mentioned before, you could also use two 18v TVS diodes over the two power rails.  e.g. P6KE18
http://nz.rs-online.com/web/p/tvs-diodes/6255436/
Spike protection for <$2
Google "The 48 volt phantom menace returns" or "Convention Paper 7909"
Figure 24 shows the TVS diodes.
Leo..