13 Jan
2012
13 Jan
'12
1:13 a.m.
-----Original Message-----
From: cctalk-bounces at classiccmp.org
[mailto:cctalk-bounces at classiccmp.org] On Behalf Of David Riley
Sent: 13 January 2012 05:46
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Defender power requirements?
On Jan 12, 2012, at 10:00 PM, Ethan Dicks wrote:
There is some times a statement that the power voltages should never cross
which implies there is also a power off requirement as well...
One thing to be careful of is that 4116s are
sensitive to the order
that rail voltages are applied and removed. Some classic memory
circuits explicitly control the order, but others I've seen are less
stringent, depending on, I think, charging a large
electolytic cap on
the rail that is supposed to be brought up last
(can't remember the
proper order - someone else here might, or it should be in the
datasheet). You should be able to find the schematics for the
Defender power supply - be on the lookout for any parts
that look odd
or look like they might affect on/off or rise
time.
Good to keep in mind. It's worked fine with the AT supply so
far, and I don't remember seeing a sequencing requirement in
the datasheets, but it's possible I overlooked it. Jameco
still sells replacements fairly cheap, but I don't relish the
thought of having to replace 24 of them. :-)
- Dave