Path: news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail From: David Wade Newsgroups: uk.d-i-y,sci.electronics.design Subject: Re: Current consumption of LCD kitchen timer? Date: Sun, 11 May 2025 21:40:08 +0100 Organization: A noiseless patient Spider Lines: 72 Message-ID: References: <36uu1k9dnlnle60okphglgqdnb9i88umgg@4ax.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Injection-Date: Sun, 11 May 2025 22:40:09 +0200 (CEST) Injection-Info: dont-email.me; posting-host="618d3cdcb0f2d1c36319a8644e2cb22c"; logging-data="87783"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX199MxsnrALrMXAQ3DiXNSHg" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:z3KzrJ5a04yQcIgy7LEuZQ5uFbA= In-Reply-To: Content-Language: en-GB On 11/05/2025 20:45, john larkin wrote: > On Sun, 11 May 2025 17:51:56 +0100, 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. > > That sounds anoying. I use a mechanical timer with "extended ring" and > sometimes want to drown it. > >> >> If this is done a couple of times a day, would the AAA battery run out >> in an appreciably shorter time? > > Wild guess 50 mA. A good (not Amazon) AAA is good for about an > amp-hour, which is 20 hours of beeping. At 2 minutes/day, it 's good > for roughly 600 days. Replace the batteries every year. > > What are you cooking? My biscuits are critical. One minute over or > under wrecks them. I set the timer to 15 minutes and start inspecting > from there. > > > > I think that the equipment to measure probably costs more that a years supply of batteries..... Dave