Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail From: Paul 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 Organization: A noiseless patient Spider Lines: 71 Message-ID: References: <36uu1k9dnlnle60okphglgqdnb9i88umgg@4ax.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Injection-Date: Mon, 12 May 2025 07:13:37 +0200 (CEST) Injection-Info: dont-email.me; posting-host="8deda79fc818ae8fb822909f2daafdcd"; logging-data="986491"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19i7G+pDi0M8XMRyPn24+9V28KzhoZZsy4=" User-Agent: Ratcatcher/2.0.0.25 (Windows/20130802) Cancel-Lock: sha1:fydsaIMjoAqGgjth+awwd2ebgpU= In-Reply-To: Content-Language: en-US Bytes: 3950 On Sun, 5/11/2025 4:57 PM, john larkin wrote: > On Sun, 11 May 2025 16:32:03 -0400, Phil Hobbs > 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 >>>> wrote: >>>>> On 5/10/2025 9:58 AM, john larkin wrote: >>>>>> On Sat, 10 May 2025 14:37:40 +0100, Pamela >>>>>> 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.