[time-nuts] HP Stories: Battery Chargers, and a fading idolization of HP

[Julien Goodwin]

On 10/2/19 11:18 pm, Rice, Hugh (IPH Writing Systems) wrote:
> The AC transformer in the 5061A/B was from HPs transformer organization (HP actually made their own transformers for many years), and whoever designed the original power system left a lot of "brown out" margin in the system.    There is a "115/230"  switch on the primary side of the transformer, but the system was designed to work well in low voltage 100 VAC countries.    The input AC voltage could go down quite a lot before the main 18.7V power throughout the 5061A/B would start to wilt.  


Whilst that's nice for some cases, it does mean that if your line
voltage is a tad on the high side (despite nowadays being a nominal 230v
country 252v is pretty standard inner-city line voltage in Australia,
260v is out of spec, but not unheard of) you end up dumping a heap of
power as heat. This of course often hurts the lifetime of kit.

Back in the day you'd have transformers with separate 220v & 240v taps
for this purpose, but they've become fairly rare. I've been tempted to
get 240:220v autotransformers for some more notable bits of kit that are
affected badly by this, but so far haven't bothered.