I bought a musical birthday card with a small circuit in it hooked up to a piezo speaker. I took the circuit out and realize that it was ridiculously simple (from what I can see). So I was thinking if there is anything I can do to change the song it came in with ? (I was thinking checking each contact point with an oscilloscope when it runs but I don't have an oscilloscope)

I do suspect that the song is recorded in the white blob in the middle of the circuit, so any tips on breaking it open?

EDIT: This whole post and idea will be abandoned as there should be no possible way for me to hack a musical birthday card. Thanks to everyone who answered.

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    \$\begingroup\$ The song might be burned into the asic rom. Not worth your time hacking, get a cheap micro \$\endgroup\$ – Voltage Spike May 13 '17 at 4:25
  • \$\begingroup\$ Any recommendations for one this small and cheap ? \$\endgroup\$ – See Jian Shin May 13 '17 at 4:34
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    \$\begingroup\$ It's probably a chip like this. All ROMs. \$\endgroup\$ – CL. May 13 '17 at 7:05
  • \$\begingroup\$ I'd assume you could "circuit-bend" your card to the point that it was possible to generate a new song by adding additional computer-controlled resistors. \$\endgroup\$ – Richard May 13 '17 at 9:28
  • \$\begingroup\$ There are recordable greeting cards sold, but to get something directly comparable to the original you'll likely need custom circuitry made of the thinnest surface mount parts on a thinner than usual PCB substrate - this would not be a particularly challenging project as use of such goes. \$\endgroup\$ – Chris Stratton May 13 '17 at 14:54

The other people have addressed why it is unfeasible (or ridiculously anti-economic) to hack that chip. I'll address another approach.

Since in a comment you say you own an Arduino, but you deem it is too big for your intended application, I suggest getting one of these Arduino clones.

They are dirty cheap and quite small. They miss the USB interface, so they must be programmed via an USB-to-UART module like this.

You may adapt this code to make your tiny Arduino board to play the melody you want.

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    \$\begingroup\$ An ATtin85 is actually substantially better for (uncalibrated) audio playback than an ATmega, as the PWM clock can run many times faster. \$\endgroup\$ – Chris Stratton May 13 '17 at 14:32
  • \$\begingroup\$ @ChrisStratton Yep, but I didn't know of any "el-cheapo" attiny dev board that supported by the Arduino environment. I feel that, being the OP already an Arduino user, it might find that solution easier. Anyway, If you have some link to share to some Arduino-compatible cheap attiny boards, that would be awesome! \$\endgroup\$ – Lorenzo Donati supports Monica May 13 '17 at 14:46
  • \$\begingroup\$ The ATtiny85 has several Arduino ports, but it the Arduino framework may be too heavy for this project. Miniaturization to the degree desired is likely going to require a willingness to make custom hardware. \$\endgroup\$ – Chris Stratton May 13 '17 at 14:51
  • \$\begingroup\$ @LorenzoDonati thanks but I really do not think these boards are easily available to me anytime soon because of where I live. I will definitely consider this option as I am a lot more familiar with arduinos compared to other ICs or microprocessors. \$\endgroup\$ – See Jian Shin May 19 '17 at 7:08
  • \$\begingroup\$ @LorenzoDonati I can't believe you haven't seen these \$\endgroup\$ – Dmitry Grigoryev May 19 '17 at 10:56

It is unfeasible to change the song. It is stored in the bare chip that was epoxied to the board in manufacturing. It is not a rewritable memory of any type.

  • \$\begingroup\$ That's sad, so this means that there is no way I can change the song right ? \$\endgroup\$ – See Jian Shin May 13 '17 at 4:05
  • \$\begingroup\$ @SeeJianShin there's is no way, unless you cut the speaker off and add a tiny chip that can play music, which is pretty much replacing the entire circuit. Only useful thing you would be able to salvage is the speaker. The thing in the white blob cannot be reprogrammed. \$\endgroup\$ – Bradman175 May 13 '17 at 14:56

Probably song is stored in ROM and you can't do anything except replacing the chip. Good news is you don't need the exact same chip, any microcontroller would work. Bad news is that power available from the card is probably least suitable, so you would need power conversion and in any case you will drain the batteries much faster. And the appearance... You will have a full featured pcb instead this white blob. Arr you sure you want it?

  • \$\begingroup\$ I do have microprocessor (arduino) but I do not want to use it in this project because the microprocessor is huge. So does this mean that the whole chip is used to store the song ? \$\endgroup\$ – See Jian Shin May 13 '17 at 4:07
  • \$\begingroup\$ The white blob covers a very small chip with ROM, simplest DAC and a couple of inputs and outputs. It's under the blob mostly because other packaging would be too expensive for such application. So arduino or similar is your only option. \$\endgroup\$ – Gregory Kornblum May 13 '17 at 4:11
  • \$\begingroup\$ Yeah I spent time trying to break open the white blob but no hope so far. Guess will have to abandon this chip for now \$\endgroup\$ – See Jian Shin May 13 '17 at 4:35
  • \$\begingroup\$ There are very small solutions smaller than Arduino size. This is the smallest I've seen as a project, based on the ATTiny's which can be programmed in the Arduino environment....but you could use an SOIC to make it even smaller: elm-chan.org/works/sd8p/report.html \$\endgroup\$ – Jack Creasey May 13 '17 at 5:22
  • \$\begingroup\$ @JackCreasey Cripes. I hadn't noticed that link until after I posted an answer. That looks like an interesting catch you made! \$\endgroup\$ – jonk May 13 '17 at 5:42

It sounds as though all you want to do is to change the song. But they aren't designed for this and it would be either (1) impossible; or, (2) requires expensive tools and skills.

  1. It's possible that the memory for the song is, itself, part of the IC mask and it is completely impossible to change it. If so, they would have to do separate masks for different songs. This isn't all that likely. But whether or not this is done will depend on business issues we are unlikely to work out here. If it happened that way, you can't change it.
  2. It's possible the IC uses fusible link memory (been around for decades.) This is, in effect, one-time programmable memory. This means there is only one (blank) chip and that they can program different songs. But only once. When it has been programmed, you can't change it.
  3. It's possible that the IC uses flash or some other re-writable memory. It's more expensive than one-time programmable ICs. If it happened this way, then you could re-program it. But you have a very expensive problem. You'd need to remove the epoxy covering and you'd need either a wire-bonder or else wafer test probes and associated skills. Again, this is very unlikely to happen and it is uneconomic for you, regardless.

That exhausts the possibilities. And.. well, you can't do it. It's either impossible or it requires tools and skills you can't afford and don't have. (You couldn't have asked the question, if you had them.) Bottom line: NO.

That said, you still can do it on your own. You don't have to buy an Arduino to do it. You can get a microcontroller IC for about a dollar that probably has enough memory available to record a small snip of a song equivalent to what you heard in the card. You'd need some programming tools (not expensive) and you'd need to find and/or develop code of your own (skills, time.)

But as always, with enough time, money, and skills, nearly anything can be done.

You may be able to find a product on the market that makes this easier. If so, just google for it. (I'm not going to do that.) It's possible that someone is making a toolset to put this kind of ability into the hands of artists. So search around for it. Or perhaps someone has a nice DIY page on the idea?

Aside from that, you can always just buy one of those dirt cheap MP3 players. They come very, very cheaply these days and can be about the size of a postage stamp. You download all the songs you want, too. Audacity+Lame is free software that can help you make your own, too, if you have a microphone.

If you were serious about making it exactly the same size as the blob on that card, and assuming you can't reach the FAB brokering price point where you design your own IC and buy a wafer as part of a brokered FAB process somewhere, you will need to contact the microcontroller vendors and ask for a waffle pack of dice. Some will sell them to you (they sold them to me and I'm just a dumb hobbyist.) You might need to convince them you won't static-zap them on accident and then blame them for shipping you "bad parts." And you most certainly will need access to a wire bonder and the skills to use one. (Or else those wafer test probes and associated equipment for them.) But you could get there in small qtys (I was making 100's at a time borrowing a wire bonder from a local company with someone to help train me, too.)

But seriously. Give up on the idea of re-programming a song into that card or of making something just as small. Unless you have the desire, the money, and time to learn lots of new skills.

  • \$\begingroup\$ Thank you so much jonk. Really appreciated the answer. I don't actually need the whole device to be that small (just has to be flat, even about A5 size is okay). The mp3 idea is so good though. Thanks again and I'm abandoning this chip. \$\endgroup\$ – See Jian Shin May 13 '17 at 6:02

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