When I put an AA cell in my voice recorder, the menu asks if it's
NiMH or alkaline.
Could the recorder be working differently depending on what type of
cell I am using?
Perhaps the type of cell affects the battery gauge, low voltage
switch off, etc. Maybe there is even something in the functional
electronics which can be made to work differently?
The voltages are different. So on something simple and/or old fashioned,
NiMH may look a bit like a low battery (except that it obviously knows
of the existence of NiMH).
"Voice recorder" is really not giving us much to go on.
I would guess this is now a feature of many voice recorders. Mine is
a Sony and I imagine several models in the range will work the same
way. This is the one I have:
I tell it alkaline when I use alkaline and NIMH when I use NIMH. Are
you expecting something different?
In the past I would say not and I never saw the option presented but
I'm not familiar with the latest developments in electonic components
and wonder if this may have changed.
Based on your up to date knowledge of electronics, do you know
anything about this?
There's honestly no need to provide an ambiguous answer to every
question I ask if you have nothing to say.
That's quite likely. Alkalines, NiMH, and lithium primary cells
differ a lot in their initial voltages and in their discharge curves.
Alkalines start out at somewhat above 1.5 volts, and decrease in
voltage gradually until fully discharged. Lithium primary AA cells
start out at above 1.8 volts, and also drop gradually while
NiMH and NiCd start out at around 1.35 when fully charged, drop fairly
quickly to around 1.2 or so, and stay there with little change until
almost fully discharged... at which point they fall off the edge of a
So, a low-battery detector or charge-level indicator does need to
adapt to the characteristics of the battery in question if it's going
to give useful results.
Can anything fancy be done nowadays in the electronics (such as a
changes in audio bias voltage) for the circuits to continue to work
at lower voltages? I rather doubt it but who knows if there's some
impressive new changes nowadays.
There are certainly tricks you can play with the electronics,
depending on what you're willing to give up and how much you're
willing to pay. There are some pretty hard stopping-points,
though... if you want to use silicon bipolar transistors and diodes,
for example, you're going to need more than .6 volts of headroom if
you hope to get them to "turn on" with any useful amount of current.
Another approach is to incorporate a voltage booster circuit... for
example, the popular "Joule thief" which lets you use a white LED
(needing 5 volts or so) with a single alkaline battery as the power
Diminishing returns will still getcha, though. By the time an
alkaline drops to 1.2 volts, or a NiCd/NiMH to 1 volt, it's got only a
few percent of its original energy content left, and you won't get
useful work out of it for very much longer even if your device has a
splendid tolerance for low-voltage input. A Joule Thief might be able
to eke out the last few percent from the battery... but then device
goes dead rather abruptly when the battery is sucked dry.
On Tuesday, 11 April 2017 01:06:54 UTC+1, Dave Platt wrote:
I';ve noticed that computer memeory chips workign voltage has decreaced over the years was 12V with DTL then 5V was popular for a long time now most seems to be 3.3V and 2.5V although I;ve seen laptop memory go down as low as 1.8V
There are some pretty hard stopping-points,
LM2623 amonst others.
It;s then importantn to not just know about the voltage but the actual power that will be needed (somethig our students don;t always get)
if a white LED runs at 4.5V 20ma then running it from one AA batt
will require at least 60ma so they shouldn't expect the batts to last too long doing something like this.
It's nice many electronic devices such as my recorder now run on
1.5 volts. I had a few 1.5 volt recorders years ago but they were
never as nice sounding as my modern Sony and I wonder if that was
down to the voltage provided for the mic.
Back then I had to use a battery box to drive an external electret
with a higher voltage than provided by on-board Plug In Power.
Back in the late 70s/early 80s, consideration was being given to
improving reliability of NiCad powered devices by replacing a battery of
say 5 AA Nicads with a single D cell to provide the nominal, in this
example, of 5volts by using a high efficiency low input voltage switching
inverter (circa 95 to 97 % efficiency at 50 to 100mA tops) to power the
battery operated portable gadget.
The idea was to eliminate the oh so common hazard of reverse charging
the weakest cell in a string which would reduce the capacity yet further,
swiftly aggravating this condition with each fresh attempt to recharge
and squeeze the *stated* capacity out of the battery, resulting in the
whole battery being rendered worn out despite the remaining cells more
than likely having better than 80% of their original capacity left.
The problem wasn't too bad when *only* a pair of such cells needed to be
employed since the task of detecting when the battery was in danger of
reverse charging one its two cells was considerably eased, allowing the
power management to shut off the equipment well before there was any
danger of damaging the weakest cell.
A two cell NiCad battery only provides a usable voltage in the range of
2.7 down to 1.3 volts which for most portable kit of the last century was
insufficient without some form of low input voltage high efficiency
switching converter. Unfortunately for the end users, this was an idea
that was regarded as a needless manufacturing expense by most makers of
domestic battery powered kit (it was far cheaper to simply incorporate a
3 or 4 cell AA battery compartment and have their customers shell out
that little bit extra on batteries).
After almost four decades, I expect the advances in switching voltage
converter technology have finally reached the stage whereby it is now
possible to supply a hundred milliamps or more at 5 or 6 volts using a
single 15AH D cell instead of resorting to a battery pack of four AA or C
cells to do the job much more expensively.
Even if you can only purchase your D sized NiMH cells in pairs, it would
be reassuring to know that you will be able to get the full service life
out of each one without any risk of reverse charging damage that would
otherwise see you chucking away a whole set of four cells for the sake of
just one bad cell.
The biggest "Fly in The Ointment" with such a scheme, lies with the
problem of high resistance contacts inherent with the classic "Torch
Battery" design of AA, C and D cells which is aggravated in the case of
rechargeables being expected to survive some 500 to 1500 charge/discharge
cycles ignoring the inevitable deterioration of the contacting surfaces
which one shot primary cells neatly avoid by the simple fact that each
fresh set of primary "Torch Battery" cells comes complete with a brand
new set of untarnished contacts. :-(
Back in the 70s I had a pocket calculator with a vacuum fluorescent
display rather than LEDs, powered by two AA batteries (alkaline or NiCad
or mains PSU/charger). Since VFDs require an 18V HT, there must have
been some kind of step up converter.
Sure. NiCds were invented 100 years ago and in commercial production
since at least the '50s. I had GE NiCds in the mid-'60s[*]. By '70
NiCds and plug-in charger modules were generally available in drug
Sorta like these:
Thats not a bad old meter I've got a 8050A and its fine c/w batteries.
The only problem with them these days is the LCD screen can be a bit
faded but several, see U tube, have done replacement screen adaptions
which do look very good.
Still use a model 45 Fluke, excellent dual display unit....
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