Re: Current consumption of LCD kitchen timer?

On 20:45  11 May 2025, john larkin said:

On Sun, 11 May 2025 17:51:56 +0100, Pamela
<pamela.private.mailbox@gmail.com> wrote:

On 17:15  10 May 2025, john larkin said:

On Sat, 10 May 2025 10:56:01 -0500, John S <Sophi.2@invalid.org>

On 5/10/2025 9:58 AM, john larkin wrote:

On Sat, 10 May 2025 14:37:40 +0100, Pamela
<pamela.private.mailbox@gmail.com> wrote:

>
>
I'm interested to know the current drawn by a kitchen LCD
digital timer.
>
(1) How much current does the timer draw when counting time?
>
(2) How much current is drawn when the piezo buzzer is sounding?
(Averaging out beeps and silent bits.)
>
My guesses are 2mA and 25mA, respectively. Is that about right?
>
>
I mean a timer similar to this one, running off a 1.5V battery.
https://www.amazon.com/Digital-Kitchen-Timer/dp/B00GOPICNM

 
That suggests a product line: a series of batteries (AA, AAA, 9v)
that measure current wirelessly, or datalog.

>
Hey! I like that idea!

 
A small PCB could have a tiny lithium battery and a uP with an
internal ADC. A diode would make a logarithmic current-to-voltage
converter from picoamps to milliamps. May as well report
temperature too.
 
Someone could sketch a schematic to discuss. It needs the right uP
and some code. And some mechanical design.
 
Might not handle high peak currents, amps.
 
Of course the electronics could be in a box with a tiny flex
running to the dummy battery. Or just squeeze the flex between the
battery and a contact. Or just sell the flex, with banana plugs on
the other end to go into a DVM. That's too easy.

>
I asked about current consumption because, when the time is up, I
leave my kitchen timer beeping until it cuts out. That's usually a
minute of beeping.

 
That sounds anoying. I use a mechanical timer with "extended ring"
and sometimes want to drown it.
>

If this is done a couple of times a day, would the AAA battery run
out in an appreciably shorter time?

 
Wild guess 50 mA. A good (not Amazon) AAA is good for about an
amp-hour, which is 20 hours of beeping. At 2 minutes/day, it 's good
for roughly 600 days. Replace the batteries every year.
 
What are you cooking? My biscuits are critical. One minute over or
under wrecks them. I set the timer to 15 minutes and start inspecting
from there.

When I'm cooking the radio is on, the big extractor fan whirring away
and the tap gets left running (yes!). So beeps from the timer add only
a little more noise.

That extra minute of beeping is useful when cooking something like
pasta (or maybe a hard boiled egg) and you want to cook for just a bit
longer.

The question is ... is this truly wasteful on the battery or does it
make little difference?

I suspect a piezo buzzer doesn't emit repeated sets of beeps without an
external chip, so the spec sheet may not contain the consumption info.