27 Feb
2005
27 Feb
'05
12:55 a.m.
first, you can't consider an under the covers part a feature... there are
plenty of small companies out there doing transformer winding so cost
wasn't that much more than a standard transformer. Keep in mind that this
product was developed back in the late 70s/early 80s. It was before small
switching supplies and you couldn't find a standard transformer with three
secondary taps anyway. There was room for one transformer and adding a fan
would have made noise. In the long run, you would have had to dissipate
more power, require larger parts for the power supply section along with
heatsinks, require a larger cabinet, and added a fan that made noise. The
box retailed for around $4K and these were sold in the hundreds. If it was
a higher quantity product, then cost reduction would have been more important.
secondly, all the EM series used the same transformer for 110V 60Hz.
best regards, Steve
At 08:22 AM 02/27/2005, Joe R. wrote:
At 10:35 PM 2/25/05 -0500, you wrote:
basically to get the constant voltage output even
when the AC supply goes
from 90 to 120. A normal transformer will "follow" the line voltage. The
power supply board uses schottky diodes and the transformer puts out just
enough voltage to be regulated to five volts with minimal power loss (there
are a couple of other secondary windings for + and - 12 for RS232). With a
normal transformer, the power supply design would have to been different to
deal with the higher wattage that it would have had to dissipate.
I understand all that but AC power is cheap and so is a fan to dissapate
the excess heat. It's surprising to see a company spent money for features
like this unless there is a very real requirement for them. Even HP doesn't
go to this length with their power supplies.
The
transformer was custom wound for AMC.
And expensive I'll bet!
By the way, the EM189 was a 6809 emulator...
Oops. I guess it was late and I was tired. I had it setting right in
front of me and I still got it wrong. I should have said EM-180B. I'd sure
like to find a pod for it but it doesn't look likely. BTW I'm assuming
that the transformers for the various models all put out the same voltage.
Is that true?
Joe