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From: Paul <nospam@needed.invalid>
Newsgroups: uk.d-i-y,sci.electronics.design
Subject: Re: Current consumption of LCD kitchen timer?
Date: Mon, 12 May 2025 01:13:31 -0400
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On Sun, 5/11/2025 4:57 PM, john larkin wrote:
> 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.
> 

Does a piezo run off 1.5V ?

This sounds like alien technology.