[sdiy] The annual I/O impedance/protection thread! (bumped)

[Neil Johnson]

> So - I'm talking about modulars. Specifically +/-12V power supply,
> 10V PP AC waveforms, 0-5V CV and a level of protection based on the
> fact that I will have no control over who will be plugging what into
> where.

Is this for your own modules for your own use, or for products that you 
plan to sell?  In other words, is there any element of product liability 
in this discussion?

Consider that many mixing desks can supply +48V quite easily, and that 
its possible that it could be presented to an output (perhaps your 
customer is using an XLR-to-jack lead and accidentally left the phantom 
power switch in the ON position).

So, again, let me ask: what sort of protection are you looking for?  Or, 
put another way, how robust do you want your products to be?

For example, you don't specify what front panel connectors you plan to 
use, but lets say its 3.5mm.  Do you want to protect against your 
customer's kid brother plugging in a 3.5mm jack from a wall wart into 
one of your output sockets?

So far all the numbers you've quoted relate to signals your modules 
produce.  But connectors can connect to anything, be they other modular 
kit (as seen in Cambridge at the weekend just gone), mixing desks, or 
anything else that happens to fit.

Neil
-- 
www.njohnson.co.uk