View Full Version : NeoPixel Teensy 3 Green AC Mains Clock Project The greenest AC Mains Clock in USA!

10-05-2013, 01:58 AM

It's nearing Christmas time and we decided to design and build an unique electronic practical gift.
This novelty gift includes using the miniature and easy to use Teensy 3 ARM Stamp. What we came up with is a digital clock which is probably the greenest AC mains clock in the USA!

When you are not using your lights you turn them off to save energy.

When you are not using your heating/cooling HVAC equipment you can turn your thermostat down/up to save energy.

When you are not using your household digital clock(s) you cannot turn them off to save energy or you will lose time or you will need to set every clock every time on power interruption. Visit any Target, Costco, Walmart and Sears store and look for AC mains clocks and you will find that the only ones they carry are "energy vampires" on for 24/7 and wasting energy - the American way of life. There is no such thing as a “green" AC mains clock because most digital clocks are NOT designed to be turned on or off ... until now!

The "NeoPixel Teensy 3 Green AC Mains Clock" will not waste energy when not being used due to new advanced technology. NeoPixel RGB LEDs can be daisy chained and "blanked" when not in use to save energy. Also, the Teensy 3 ARM stamp can be forced to sleep to save energy. Combine both features with a battery protected, precision RTC and you can have a very energy efficient, precision AC mains "green" clock. Our clock, when not being used, sleeps 97% of the time and only shows the time automatically on every minute rollover. Also, an optional IR remote or PIR motion sensor can trigger the clock display to save even more energy.

With all new technology comes at a price. Each Flora V2 NeoPixel module cost $2 USD each. 13 Flora V2 NeoPixels used x $2 = $26 + ($19 - T3) + ($25 - PCB) + ($20 - misc components) Having the only greenest AC mains clock in the USA --> is priceless!

For hackers, perfboarding this design with thru hole components will reduce the cost by about 50%.
(See NeoPixel_Clock_schematic.PDF)

If everyone goes "green" and builds a NeoPixel clock they can reduce their carbon footprint and get rid of several coal fired power plants or even a Nuclear Power Plant! (See "NeoPixel_T3_Clock_Design.PDF" for explanation.)

10-05-2013, 02:02 AM
Attached pics

Picture one (left) - This is no mistake ... shows the clock state 97% of the time. :cool:
Picture two (center) - Front of NeoPixel clock - time is 9:30 PM.
Picture three (right) - Back of NeoPixel clock - shows Teensy 3.


10-05-2013, 02:17 AM
Project Design Files:
Design PDF and schematic PDF



10-10-2013, 08:27 PM
NeoPixel AC Mains Clock Design Update FYIO ...

Current testing measurements indicate that the Teensy 3 and RTC, when in "deep sleep",
consumes only 237 uA. The 13 NeoPixel clock ring, without any NeoPixels on, consumes
10.68 mA. which is unacceptable for battery use. A NPN transistor driver(2n2222 or 2n3904) was
installed to shutdown the NeoPixel clock ring supply power when the Teensy 3 is put into a low-power sleep mode.
This allows for battery portable operation of the NeoPixel clock for months in the emergency or survival
clock mode.

Note: Each NeoPixel (all three LEDS on) consumes ~60 mA. x 13 = 780 mA. Each clock NeoPixel RGB color uses a
lot less power due to the software brightness control is reduced to 5 from the brightness range of 0-255.(Max)
Also, only the primary colors of red and green (not blue) are used and never mixed in the clock design
to save joules. Exceeding 200 mA. by a software bug or programming error, will blow out the transistor driver!

10-13-2013, 09:59 PM
We went down to get a burger at McDonalds and within 1 hr. our NeoPixel T3 clock project views jumped by 300 - impossible.
There is something wrong with the new server?:confused:

Now they jumped by another 200 ?
Something or somebody does not know how to count!

Now it went from 305 to 1132 views?

10-13-2013, 11:33 PM
You are on hackaday.com :D


10-14-2013, 01:01 AM
To the HACKADAY brotherhood ... your questions...

There are provisions for IR control and a PIR sensor to display the time whenever it’s needed,
but that would obviously mean a hit to the energy efficiency.

By having an optional remote IR control to turn the clock on "by demand" would reduce the power
consumption. Of course, the 1 minute rollover would be disabled and 1440 clock displays would
be eliminated per day.

Now, there’s nothing wrong with building a unique expensive low-power clock. But combining
it with comments about how other clocks represent the “American way of life” and making
implausible claims about bankrupting electricity utilities is silly.
I believe you missed the author’s dry sense of humor. Maybe now I’m missing yours :)

Do I hear a Bingo in the house? We have a winner!

We try to design and build electronic devices that no one has yet constructed to date.
Like a laser vehicle parking guidance system, A Doomsday clock, a battery operated uSD high performance data logger
all using the unique capabilities of the Teensy 3 ARM Stamp. (Arduino compatible)
Fellow hackers enjoy.
BTW... All the above projects are here on this board with schematics. We leave the software up to you.

What is wrong with a low power RTC circuit and a push button to see the time.
A bit like some of the old school 1970′s watches with 4 digit, 7 segment LED’s.

The Tact switch you see will do this in the battery operated emergency mode.
Remember Katrina? This clock will run for seven years, in extreme temperatures, without human intervention
and two months on batteries due to the fact the Teensy 3 ARM Stamp can be put to sleep.
Other than being a novelty clock, this NeoPixel clock can be used as an emergency or survival clock -
it even shows the date in the emergency battery mode!

I’m curious why they didn’t use the built-in RTC.

The NeoPixel clock DS3232MZ+ "TCXO" RTC has a +-5 PPM / 0.43 secs/day or 2.63 min./yr.
A 50 PPM watch crystal would give ~ 26 minutes per year and it would not be temperature compensated.
The clock time is rounded to every 5 minutes but the external RTC is good to 5 PPM.

I see what looks like a Barrel jack feeding power into this circuit. Presumably thats DC power
being supplied by an AC-DC “wall wart” adapter. I would wager the energy inefficiency of that
power supply is dwarfing whatever power efficiency they’ve designed into this circuit.

Its powered by an 70% efficient switch mode regulator. Sparkfun TOL-08269
Note: It could be powered by any high efficiency power supply (5 VDC +- 5%) and even two AA batteries with boost converter.

mike says:
October 13, 2013 at 5:50 pm
If you’re going for extreme power efficiency, there are a significant number of
poor choices going on here. First… LED is not an efficient display medium
compared to other simple-to-use technologies such as LCD. Think of how long a
digital wristwatch runs on a tiny button cell battery – mine is going on six years.
And that’s running full-time, 24 hours a day. The second issue here is the
particular LEDs used. These are not high-efficiency units, they’re high-intensity
RGB pixels with integrated communication circuitry. And they are run with a
processor hammering along at 24 effing MHz, why? Then the processor runs at
3.3V but the Teensy is fed with nominal 5, so there’s a LDO onboard eating the
rest of that. Thankfully the LEDs themselves run straight from 5, but the RTC runs
off a second LDO for more loss. But of course the greatest loss is in the
conversion of AC mains to 5V DC, which will almost certainly eclipse the
consumption of this board and probably by several times, even if it is a
“high efficiency” switcher.

For a really efficient setup still built DIY, check out the experiments
done on MSP430s driving LCDs while powered from supercapacitors, posted
here some time ago:
http://hackaday.com/2010/09/30/launchpad-takes-ultra-low-power-to-the-extreme/ … combine
such a display system with a more efficient power source (solar is an oft-used example
but there are others, such as ambient RF harvesting), or even leech off the usage of
another appliance using a few loops of wire around the AC feed. There are better
ways to do low-power…

FYIO ...

The second issue here is the
particular LEDs used. These are not high-efficiency units, they’re high-intensity
RGB pixels with integrated communication circuitry.

The NeoPixel brightness range is from 0-255 max. We turn it down to 5 to save joules of energy.
Without that brightness control, we would agree its a very inefficent LED but keep in mind
the NeoPixels are sleeping 97% of the time.

And they are run with a processor hammering along at 24 effing MHz, why?

The Teensy 3 can run from 24 Mhz to "overclocked" 96 Mhz. Since the Teensy 3 is put to sleep
at 237 uA and is only awaken when the interrupt alarm from the RTC rolls over every minute then
only the Teensy 3 is used during the split second to display the time. It also sleeps 97% of the time.
We ran the Teensy 3 at 24 Mhz instead of 96 Mhz to reduce the peak power during the display time.

Note: A special driver transistor circuit drives the supply of the NeoPixel ring. When the Teensy 3
is put to sleep also is the NeoPixel clock ring.

For a really efficient setup still built DIY, check out the experiments done on MSP430s driving LCDs while powered from supercapacitors, posted here some time ago:

The MSP430 can sleep at 1 uA and with a LCD it probably can be very power efficient BUT other
than that it would "bite the dust" against the processing power of the Teensy 3. Processing
power is needed by the critical timing for the NeoPixels, the command line interface and
all the special clock algorithms like the automatic daylight savings time adjustment algorithm.
Keep in mind, this clock can run under extreme "ambient" temperatures for seven years without any human
intervention. Also, precision timing is added, to this project, by using the temperature controlled oscillitor (TCXO) on the
real time clock -+5 PPM.

There are better ways to do low power but we chose the practical way of doing it. :cool:

Whew! ...Most, if not all, questions could have been answered by just reading the attached project design doc or
viewing the schematic of the NeoPixel Teensy 3 Green Clock. ;)

Link to HACKADAY...


10-26-2013, 02:38 PM
Final schematic update - attached.
Enjoy :cool: