Current consumption of LCD kitchen timer?...

P

Pamela

Guest
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
 
On 10/05/2025 14:37, 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?
Click to expand...

At least 100x too high for the basic clock consumption. According to
<http://www.technoblogy.com/show?19K8>, the average power consumption is
about 10µA. It would depend on the clock processor, display and driver,
etc, but a few microamps would be typical. It could be even lower - I
once had an LCD clock (not a timer) I forgot I had and found it in a
drawer still displaying after 20 years (surprisingly with a Toshiba zinc
carbon AA battery powering it. From what I remember, the battery
voltage, measured with a digital voltmeter, was less than 1V!).

I mean a timer similar to this one, running off a 1.5V battery.
https://www.amazon.com/Digital-Kitchen-Timer/dp/B00GOPICNM
Click to expand...

--
Jeff
 
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
Click to expand...

That suggests a product line: a series of batteries (AA, AAA, 9v) that
measure current wirelessly, or datalog.
 
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.
Click to expand...

Hey! I like that idea!
 
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!
Click to expand...

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.
 
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.
Click to expand...

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

Joe
 
On 5/10/25 9:15 AM, john larkin 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.
Click to expand...

There are a few products already available to easily do such
measurements, such as:

https://www.joulescope.com

This can also provide the time integral of consumption to be able to
predict battery life. It can be especially tricky where devices have
microamp quiescent currents together with multi-milliamp bursts when active.

If a meter shunt is large enough to measure the sleep current it can
have too large a voltage burden when the device springs to life -
accurate measurement of microvolts across the sense resistor is required.

I have measured sleep currents with an ordinary DVM fairly successfully
by putting a large electrolytic across the terminals to avoid the large
drop during the active times.
 
On Sat, 10 May 2025 18:16:19 -0700, KevinJ93 <kevin_es@whitedigs.com>
wrote:

On 5/10/25 9:15 AM, john larkin 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.


There are a few products already available to easily do such
measurements, such as:

https://www.joulescope.com

This can also provide the time integral of consumption to be able to
predict battery life. It can be especially tricky where devices have
microamp quiescent currents together with multi-milliamp bursts when active.

If a meter shunt is large enough to measure the sleep current it can
have too large a voltage burden when the device springs to life -
accurate measurement of microvolts across the sense resistor is required.
Click to expand...

A diode can make a logarithm of the current. Add an opamp to make a
zero-drop diode.

I have measured sleep currents with an ordinary DVM fairly successfully
by putting a large electrolytic across the terminals to avoid the large
drop during the active times.
Click to expand...

Kind of expensive.
 
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
Click to expand...

Unfortunately these devices are very power hungry. A three phase
supply is recommended.
 
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.
Click to expand...

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?
 
On Sun, 11 May 2025 17:51:56 +0100, Pamela
<pamela.private.mailbox@gmail.com> 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.
Click to expand...

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?
Click to expand...

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.
 
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?
Click to expand...

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

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
On 11/05/2025 20:45, john larkin wrote:
On Sun, 11 May 2025 17:51:56 +0100, Pamela
pamela.private.mailbox@gmail.com> 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.

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.
Click to expand...
I think that the equipment to measure probably costs more that a years
supply of batteries.....

Dave
 
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
Click to expand...

Whoever invented the piezo buzzer should be welded into a prison cell,
with a dozen piezo buzzers.
 
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.
Click to expand...

Does a piezo run off 1.5V ?

This sounds like alien technology.
 
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.
Click to expand...

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
 
On 20:45 11 May 2025, john larkin said:
On Sun, 11 May 2025 17:51:56 +0100, Pamela
pamela.private.mailbox@gmail.com> 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
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 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.
Click to expand...

When I\'m cooking the radio is on, the big extractor fan whirring away
and the tap gets left running (yes!). So beeps from the timer add only
a little more noise.

That extra minute of beeping is useful when cooking something like
pasta (or maybe a hard boiled egg) and you want to cook for just a bit
longer.

The question is ... is this truly wasteful on the battery or does it
make little difference?

I suspect a piezo buzzer doesn\'t emit repeated sets of beeps without an
external chip, so the spec sheet may not contain the consumption info.
 
On 06:13 12 May 2025, Paul said:
Does a piezo run off 1.5V ?

This sounds like alien technology.
Click to expand...

That was my guess based on the single alkaline cell the timer uses.

However I hadn\'t considered a voltage converter inside. I reckoned the
timer would use only the bare minumum circuitry like a counter IC and
display driver.
 
On 10/05/2025 14:37, 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
Click to expand...

Second one might be about right perhaps 10mA is more likely but I\'d be
very surprised if the display operating and timing current was more than
20uA (and it could easily be lower).

Bare metal LCDs take almost no current at all (but have to be driven
with an AC signal). They are no different at the core to LCD digital
watches with an alarm function probably even using the same chips and a
slightly beefier piezo sounder.

--
Martin Brown
 
On 12:10 12 May 2025, Martin Brown said:
On 10/05/2025 14:37, 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

Second one might be about right perhaps 10mA is more likely but I\'d
be very surprised if the display operating and timing current was
more than 20uA (and it could easily be lower).

Bare metal LCDs take almost no current at all (but have to be driven
with an AC signal). They are no different at the core to LCD digital
watches with an alarm function probably even using the same chips and
a slightly beefier piezo sounder.
Click to expand...

If beeping consumes 10mA then, in theory, you would get 100 hours of
beeping from single AA alkaline (1,000 mAh).

That\'s 6,000 one-minute \"overruns\", under optimal conditions. Let\'s say
it\'s only 1,500 in real life conditions.

In conclusion, if overruning beeping is done twice a day, then the
battery would last a couple of years.

That\'s seems slightly optimisitic because I usually change the battery
about once a year or so when I don\'t let the beeping run on. (However, the
abttery is changed largely because the display has started to dim.)
 
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