> From: Brent Hilpert
> Your conceptualisation around the role of electrons is perhaps a
> little off.
Well, I'm not taking into effect things like the velocity of electrons
passing around the circuit (more current, with the same number of electrons,
effectively), etc, but I
On Sep 21, 2018, at 6:03 PM, Noel Chiappa via cctalk
wrote:
> (Although I guess the coil
> for the buck might be cheaper than the transformer - even though the use of a
> high frequency would reduce the size of the latter - making the buck approach
> superior.)
>
> To put it another way,
On 2018-Sep-22, at 11:54 AM, Noel Chiappa via cctalk wrote:
>> From: Brent Hilpert
>
>> A glance at the schematic ... you might think it's just a linear
>> regulator
>
> And the writeup in the maint manual gives that impression too, which didn't
> help! (Hence my assumtion that it was acting in
> From: Brent Hilpert
> With the given 20-30VAC input (do I have that right?)
Yup.
> A glance at the schematic ... you might think it's just a linear
> regulator
And the writeup in the maint manual gives that impression too, which didn't
help! (Hence my assumtion that it was
On 2018-Sep-21, at 4:03 PM, Noel Chiappa via cctalk wrote:
>> From: Brent Hilpert
>
>> In typical "down-converters" there are additional current paths in the
>> supply, paralleling the input path, that can provide the 'additional'
>> electron flow rate. ... the whole rationale of a switching
On 2018-Sep-21, at 4:03 PM, Noel Chiappa via cctalk wrote:
>> From: Brent Hilpert
>
>> If the heatsinks seem huge compared to modern day supplies, that's more
>> likely the result of technology improvements - faster devices, and
>> moving from bipolar switching transistors to mosfets. Bipolar
>>
On 2018-Sep-21, at 3:20 PM, Noel Chiappa via cctalk wrote:
>> From: Mattis Lind
>
>> The H744 is a buck converter. You can read about buck converters here:
>> https://en.wikipedia.org/wiki/Buck_converter
>
> Wow, that was incredibly hard to read; no clear and simple explanation of the
> basic
> From: Brent Hilpert
> In typical "down-converters" there are additional current paths in the
> supply, paralleling the input path, that can provide the 'additional'
> electron flow rate. ... the whole rationale of a switching supply is to
> use time (varying switching
On 2018-Sep-21, at 1:03 PM, Noel Chiappa via cctalk wrote:
> Oh, one thing I forgot to include:
>
>> a lot of the incoming power in that 30V AC has to be thrown away, in
>> producing +5V.
>
> So, if my understanding is correct, the 'switching' H744 really isn't much
> better than a classic
> From: Mattis Lind
> The H744 is a buck converter. You can read about buck converters here:
> https://en.wikipedia.org/wiki/Buck_converter
Wow, that was incredibly hard to read; no clear and simple explanation of the
basic concept of how it works, before getting into the details!
>
> * If you supply a link & location to a schematic I'll take a look, I don't
> feel like wading around in bitsavers pdfs to try to find it right now.
page 207 of:
http://bitsavers.trailing-edge.com/pdf/dec/pdp11/1140/PDP-1140_System_Engr_Drawings_Rev_P_Jun74.pdf
On Fri, Sep 21, 2018 at 1:38 PM, Noel Chiappa via cctalk <
cctalk@classiccmp.org> wrote:
> My understanding is that, without using a transformer (which creates an
> independent circuit loop - more below), there's no way to increase the
> _amperage_ out of circuit over what's fed into it: since
On 2018-Sep-21, at 12:38 PM, Noel Chiappa via cctalk wrote:
> So there's something about the H744 I'm not sure I understand; hopefully those
> with more analog-fu will set me straight if I'm confused.
>
> This supply runs off 20-30V AC. It takes the input AC, rectifies it, and runs
> it
The H744 is a buck converter. You can read about buck converters here:
https://en.wikipedia.org/wiki/Buck_converter
You have a good description there.
Den fre 21 sep. 2018 kl 22:03 skrev Noel Chiappa via cctalk <
cctalk@classiccmp.org>:
> Oh, one thing I forgot to include:
>
> > a lot of
Oh, one thing I forgot to include:
> a lot of the incoming power in that 30V AC has to be thrown away, in
> producing +5V.
So, if my understanding is correct, the 'switching' H744 really isn't much
better than a classic linear supply. It still wastes a very large amount of
the input
So there's something about the H744 I'm not sure I understand; hopefully those
with more analog-fu will set me straight if I'm confused.
This supply runs off 20-30V AC. It takes the input AC, rectifies it, and runs
it through a cap to filter out the ripple. What's next is that it's an early
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