[ILUG] OT: stepping down from 12v to 9v

[Peter Dempsey]

I thought I'd wait before proposing a solution. I'm glad I did.

The simplest thing to do would to use a couple of diodes in series with the 
supply. Each diode will give about 0.6 volts of a drop. 5 in series would 
give a 3 volt drop. 1N4007 diodes would be fine providing the current is less 
than 1A.

The other solution would be to use s 7809 voltage regulator. I'm not sure how 
well it would perform with only 12 volts input but it's worth a try. Again 
this should work if the current is less than 1A.

Have fun!

Peter

On Fri 28 Apr 2006 00:32, Brendan Kehoe wrote:
> This is very OT, but I don't know of other lists that might be as useful
> for this sort of thing. :)
>
> We're trying to find an easy way to convert a 12v DC current to 9V DC
> for a community wireless broadband scheme.  We've got a tiny Ethernet
> switch that wants 9V, but a 230->13.6V transformer, who has two contacts
> (+13.6V, and a ground).  A junction box feeds one device, a WRAP board,
> that wants 12V.  But the switch wants 9V.
>
> I found that a 3.1V zener diode would do the job, but a) I've found no
> one in Ireland who sells them, and b) it would require a bit of a
> hardware hack to put it together which doesn't feel like it'd be the
> safest approach.
>
> Anyone know of a device already available that would take a 12V DC
> signal (like comes in a car's 12V adapter) and step it easily down to 9V
> DC?
>
> Feel free to reply off-list to reduce traffic, and I'll post a summary
> later.
>
> Thanks for any tips,
> B