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From: john larkin <jl@glen--canyon.com>
Newsgroups: uk.d-i-y,sci.electronics.design
Subject: Re: Current consumption of LCD kitchen timer?
Date: Sun, 11 May 2025 13:57:48 -0700
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On Sun, 11 May 2025 16:32:03 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>On 2025-05-11 12:51, Pamela 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>
>>> wrote:
>>>> 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 the question 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.
>> 
>> If this is done a couple of times a day, would the AAA battery run out
>> in an appreciably shorter time?
>> 
>
>I admire your patience.  That would drive me nuts.  I doubt that the 
>beeper requires much current--piezo sounders are pretty efficient at 
>turning battery power into annoying noises. ;)
>
>Cheers
>
>Phil Hobbs

Whoever invented the piezo buzzer should be welded into a prison cell,
with a dozen piezo buzzers.