Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail
From: piglet <erichpwagner@hotmail.com>
Newsgroups: sci.electronics.design,uk.d-i-y
Subject: Re: Current consumption of LCD kitchen timer?
Date: Mon, 12 May 2025 06:03:19 -0000 (UTC)
Organization: A noiseless patient Spider
Lines: 80
Message-ID: <vvs2v7$ukfc$1@dont-email.me>
References: <XnsB2DB94CDD19321F3QA2@135.181.20.170>
 <s8qu1kpqmo3unudah49ekkgcu3ssm9s6q7@4ax.com>
 <vvnsuh$3k0fq$1@dont-email.me>
 <36uu1k9dnlnle60okphglgqdnb9i88umgg@4ax.com>
 <XnsB2DCB5BD83C431F3QA2@135.181.20.170>
 <b5ef3e26-9231-290a-8804-1d085b12a1e5@electrooptical.net>
 <on322kpt0cl2ktjof88drm2kbp8fas9ucg@4ax.com>
 <vvs01r$u3br$1@dont-email.me>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Injection-Date: Mon, 12 May 2025 08:03:19 +0200 (CEST)
Injection-Info: dont-email.me; posting-host="24116898a23068636ab1ec4658ff5f46";
	logging-data="1004012"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX1875yg9gROPq4LO5EdGPID+"
User-Agent: NewsTap/5.5 (iPhone/iPod Touch)
Cancel-Lock: sha1:fpi4mi9USv+wJeCQmdwdJ3ZBc68=
	sha1:woeEz5dpBa9JWcLM+49rOY8ik9U=
Bytes: 4244

Paul <nospam@needed.invalid> wrote:
> 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.
> 
> 

Some do. But the kitchen timers I’ve seen have small auto transformer
(tapped inductor about size of quarter watt resistor) to make the buzzer
much louder.

-- 
piglet