16 Oct
2012
16 Oct
'12
3:25 p.m.
On Tue, 16 Oct 2012, David Riley wrote:
Date: Tue, 16 Oct 2012 17:24:03 -0400
From: David Riley <fraveydank at gmail.com>
Reply-To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at
classiccmp.org>
Subject: Re: unibus to modern disk interface?
On Oct 16, 2012, at 4:59 PM, Peter C. Wallace wrote:
A FDV301N is close and would work with 3.3V gate drive from CPLD/FPGA
Peter Wallace
Mesa Electronics
A bipolar transistor will turn off too slowly for
this use, but a little SOT-23 MOSFET will work just fine (and a series resistor in the
gate can tailor the on/off slew rates) You can get ones with less than 5 pF output
capacitance that will easily sink 100 mA with less than .7V VOL
You could keep the bipolar from saturating with a Schottky clamp, but at
the expense of even more parts. I like the idea of a FET, but I haven't
looked very hard at the available parts.
but discretes would add to the assembly cost...
Certainly. Or, if one makes a kit, they add to the headache of the
consumer. :-) Some of us don't mind soldering upwards of 40 tiny SOT
parts, but some do.
- Dave