# How do singing birthday cards work? **URL:** \ **Category:** Factual Questions\ **Created:** [September 30, 2003, 4:37pm UTC](https://boards.straightdope.com/t/how-do-singing-birthday-cards-work/204715 "2003-09-30T16:37:49Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Paco](https://avatars.discourse-cdn.com/v4/letter/p/a6a055/32.png) [@Paco](https://boards.straightdope.com/u/Paco)\ **Post date:** [September 30, 2003, 4:37pm UTC](https://boards.straightdope.com/t/how-do-singing-birthday-cards-work/204715/1 "2003-09-30T16:37:49Z")
For a school project I have to write a one page paper on how singing birthday cards work. Actually my teacher showed us a Homer Simpson bottle opener and when the metal on the bottle cap is opened by the bottle opener the bottle opener begins to make noise. He said since it is basically the same concept, if we couldn’t find information on the bottle opener we could find information on the birthday card (the ones that when you open them they play music). I have searched the web and [HowStuffWorks.com](http://HowStuffWorks.com), but I can’t seem to find anything. Do you guys have any suggestions as to where I could look? Thank you in advance, Paco. ---
**Author:** ![fotosbyfrank](https://avatars.discourse-cdn.com/v4/letter/f/54ee81/32.png) [@fotosbyfrank](https://boards.straightdope.com/u/fotosbyfrank)\ **Post date:** [September 30, 2003, 4:54pm UTC](https://boards.straightdope.com/t/how-do-singing-birthday-cards-work/204715/2 "2003-09-30T16:54:12Z")
It’s easy !! you generally have a specially burned chip with the song on it. Add a couple of other componants and a small piezoelectric speaker and you have the basics. What’s slick is how it’s activated. Take 2 pieces of plastic. Put foil on part of one side of them, and position it so that the foil part faces each other, but doesn’t touch when the card is closed. Attach the plastic strips to each 1/2 of the card. Put one lead of the battery to one of the foils, and the other lead to the 2nd foil. When you open the card, the plastic strips move against one another and the foil strips touch, and the circuit is closed - and “Happy Birthday” (or whatever is programmed) begins to play. ---
**Author:** ![Duderdude2](https://avatars.discourse-cdn.com/v4/letter/d/cdc98d/32.png) [@Duderdude2](https://boards.straightdope.com/u/Duderdude2)\ **Post date:** [September 30, 2003, 4:57pm UTC](https://boards.straightdope.com/t/how-do-singing-birthday-cards-work/204715/3 "2003-09-30T16:57:41Z")
I have the exact bottle opener! Funny stuff. Anyways, I do am interested in how those cards work (though I think I have an idea) ---
**Author:** ![Duderdude2](https://avatars.discourse-cdn.com/v4/letter/d/cdc98d/32.png) [@Duderdude2](https://boards.straightdope.com/u/Duderdude2)\ **Post date:** [September 30, 2003, 4:59pm UTC](https://boards.straightdope.com/t/how-do-singing-birthday-cards-work/204715/4 "2003-09-30T16:59:07Z")
Wow, now my post looks retarded. “How does something work that was just explained”. Impressive. ---
**Author:** ![Paco](https://avatars.discourse-cdn.com/v4/letter/p/a6a055/32.png) [@Paco](https://boards.straightdope.com/u/Paco)\ **Post date:** [September 30, 2003, 7:49pm UTC](https://boards.straightdope.com/t/how-do-singing-birthday-cards-work/204715/5 "2003-09-30T19:49:26Z")
How does this circuit make noise though? I know that you have a battery and a speaker but surely you can’t just send a current to the speaker and get it to play the song. I don’t understand what components are involved in this. Any help would be greatly appreciated. ---
**Author:** ![gazpacho](https://avatars.discourse-cdn.com/v4/letter/g/6f9a4e/32.png) [@gazpacho](https://boards.straightdope.com/u/gazpacho)\ **Post date:** [September 30, 2003, 8:03pm UTC](https://boards.straightdope.com/t/how-do-singing-birthday-cards-work/204715/6 "2003-09-30T20:03:33Z")
The components are a pizo electric speaker, Integrated circuit, battery, and maybe a separate flash to store the some but that might be in the integrated circuit since there is not a lot of data for those sorts of songs. ---
**Author:** ![Paco](https://avatars.discourse-cdn.com/v4/letter/p/a6a055/32.png) [@Paco](https://boards.straightdope.com/u/Paco)\ **Post date:** [September 30, 2003, 8:16pm UTC](https://boards.straightdope.com/t/how-do-singing-birthday-cards-work/204715/7 "2003-09-30T20:16:12Z")
I really appreciate everyone’s help. If anyone knows of a site that might have some of this information on it I would greatly appreciate it. Thank you.