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Bubble Display Alarm Clock


recently some vintage bubble displays popped up at various places [1][2], so I felt the urge to build another bedside table alarm clock, this time a really tiny one, roughly the size of an AAA battery:

Since I already built two previous alarm clocks [3][4], the build was straight forward.  Here is the simple schematic:

Here the parts used:

And here how the wiring was done:

Please find the source code attached.

A video is also available on YouTube:

Have fun,

[1] ... t-display/
[3] viewtopic.php?f=56&t=2126
[4] viewtopic.php?f=56&t=2784&p=28231#p53277

Re: Bubble Display Alarm Clock

Reply #1
Hey Markus, an impressive project.  Thank you.

Mind if I ask the source for the miniature speaker, please?

TIA.  Cheerful regards, Mike

Re: Bubble Display Alarm Clock

Reply #2
[quote author="McLaren"]Mind if I ask the source for the miniature speaker, please?[/quote]
Sure, I saw it being used in this nice project:

Google for ABMT-801-RC.  I bought mine from Farnell.

Don't expect too much in terms of sound quality from such a small speaker, though.

Re: Bubble Display Alarm Clock

Reply #3
Hi Markus,

Thanks for putting your clocks up on the net. I picked up a couple of the the HP Bubble displays as soon as I saw them and had been wanting to use them in a clock but hadn't the means so your design + code is fantastic.

I had a couple of questions, if that's OK:

1) - The schematic has a couple of caps, notably one by the buzzer, but the built item doesn't seem to neither does the photograph of 'parts'. Should the caps be used?

2) - The voltage from a single AAA is below spec for the chip, display, & buzzer. Doesn't this matter?

3) - You don't have a resistor in series with the LED, would it be good to put one in, if part+room available?

Also I'm envious of your neat tac buttons as I weary of the ubiquitous black round rod type, do you have a part # or source for them - also the LED which looks a nice rounded edge shape for free mounting, all the rectangualr ones I've seen are very hard edged.

Thanks again, Vicaro


Re: Bubble Display Alarm Clock

Reply #4
1. The buzzer capacitor from the schematic is visible as the two SMD caps between the LED and the buzzer on the board.

2. The AAA sized battery is an AAA sized LiFePo4 battery, rated at 3.4 V. I bought mine from here ... OC:AT:3160
Love them.

3. The white LED is rated for 3V, which the output of the microcontrolled is not able to provide at such high currents (20 mA).  Since the output does not get damaged, everything is fine and resistors are futile :)

4. These are the buttons I used

The LED is a standard 5 mm white LED with round head where I filed away most of the plastic :)

Re: Bubble Display Alarm Clock

Reply #5
Aha, missed the smd cap there. Thanx for being patient with my 'duh'' moments :-). Thanx, Vicaro

Re: Bubble Display Alarm Clock

Reply #6

So cool post, Thank you.

I'm testing your product, and I wonder that why need SHINING mode?
And Why measure the voltage while the LED is shining?

And I want to find out so pretty LED like you. Where did you find out it?


Re: Bubble Display Alarm Clock

Reply #7
Hi Markus,

Finally sourced all parts with the exception of battery: The speaker has got to be the world record for tiny :-)

Re batteries, could I ask how you recharge these - do you use a dedicated LiFePo4 charger?

Regards, Vicaro

Re: Bubble Display Alarm Clock

Reply #8
I do not have a dedicated charger.  Instead I hook up the battery to my bench power supply, set the voltage to 3.6 V and limit the current to 200 mA for the AAA sized cell.  This way the battery is first charged with a constant current of 200 mA and then with a constant voltage until it is fully charged (charge current below 1 % of constant current, i.e. <2 mA).

This might not be as convenient as using a dedicated LiFePo4 charger, but since the battery lasts (for this application) about 2 years, it is not that much of a hassle to me :)


Re: Bubble Display Alarm Clock

Reply #9
I'd wondered if something like this was OK so this information is great. 2 years is very a long time - these Texas Instrument ICs are impressive and some are available as samples.

Thanks once again for such a detailed and useful reply, regards, Vicaro

Re: Bubble Display Alarm Clock

Reply #10
[quote author="Markus Gritsch"]I do not have a dedicated charger.[/quote]
This has changed -- now I do have one :)  See viewtopic.php?f=56&t=7467

Re: Bubble Display Alarm Clock

Reply #11
Hi thereAll.

I am an electronic hobbyist.  Got my oscilloscope, signal generator and I restore older HP calculators, LED and LCD types along with vintage tube 50's and transistor radios.  In fact, I am writing a book on the "restoration of HP calculators from 1970 to 2000.

Came across this posting and have a question.  What is the code for that Markus has included.  Examining it suggests that maybe I need to program the M430G2xxx.  This doesn't appear to be a pic chip.  Does it fire up in the clock projects is,  pre loaded as a ROM.
The question is, if I assemble the clock as described is the IC already coded for this project?

Cheers, Geoff

Re: Bubble Display Alarm Clock

Reply #12
Google for "MSP430G2452" and you see it's a microcontroller from TI, which needs to be programmed to do anything, of course. Google for "MSP430 LaunchPad" to find a very inexpensive programmer for it. TI offers a free Ecplipse based IDE called "Code Composer Studio".

Re: Bubble Display Alarm Clock

Reply #13
Thanks Markus!

Will get the programmer.