[ARC5] Vibrator Power Supplies

[J. Forster]

> On 8 Dec 2012 at 9:59, brianclarke01 at optusnet.com.au wrote:
>
>> Dynamotors typically have a conversion efficiency of no more than 50%.
>
> Well, actually, that is OVERALL efficiency, and includes the starting
> power
> required.
>
> When running steadily, a dynamotor's efficiency is very much higher than
> that, but I have forgotten the exact figure. I know it approaches that of
> a good vibrator pack.

I'm not so sure. WWII dynos mostly had wound fields and considerable windage.

>> A vibrator supply can reach 70% easily, and often more, if designed
>> properly.
>
> Correct. However, vibrators packs are not particularly reliable when high
> power and/or high voltage is required. For instance, I doubt if one could
> build
> a reliable vibrator supply that would provide all the necessary voltages
> and currents for an ART-13, for instance.

Well, the Canadian HPA for the WS 19 put out pretty close to an ART-13 and
used a vibrator. I don't know how reliable it is.

[snip]

> I have (or had) a 300 watt vibrator pack from that period: it was
> absolutely
> IMMENSE for the power output. It would easily make 4 dynamotors of the
> same voltage and power output. And keeping vibrators working for it was a
> never-ending task.

A 300 watt supply would have has a transformer of > 15 pounds, for starters.

>> Then you need to consider the downstream effects - the filtering
>> components

[snip]

>> But with SMPSUs, operating at 1
>> MHz or so, the filtering components are very much smaller
>
> ...than for a 60 Hz AC or a vibrator supply at 115 Hz...
>
>> than for a
>> dynamotor.
>
> Please explain: I don't understand what you mean by this last.

The argument is based on the time the input waveform to the filter is
below the filter voltage. It rarely is in a dyno, is for a short time in a
square wave drive, and mostly is with a sine drive.

-John

==========
>
> Ken Gordon W7EKB
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