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From: Joe Gwinn <joegwinn@comcast.net>
Newsgroups: sci.electronics.design
Subject: Re: Current consumption of LCD kitchen timer?
Date: Sat, 10 May 2025 14:52:41 -0400
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On Sat, 10 May 2025 09:15:59 -0700, john larkin <jl@glen--canyon.com>
wrote:

>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.

Two pieces of 0.001" brass foil separated cigarette paper, all epoxied
together.  Solder wires to the brass foil before epoxying.

Joe