Sound greeting cards

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#1
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Hi Freaks,
Anybody knows how those greeting cards with sound work?
I cracked one open the other day (given to me by my wife; wife wasn't too happy but that's a different post) and was amazed to find a really simple circuit, a 3.3V Li battery, RC filter (not SMT)and a loudspeaker.There was a huge black ceramic dot which probably had a memory of some sort with the song in it? There was a switch connected to this black dot. Do those things have a memory + D/A converter to play the song? (I ended up using the 3.3V battery for my projects.)

Another one I got had a feature to record a message which you could open to listen. However, when you closed the card you lost it and had to re-record indicating that there may be some RAM there?

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Winbond (was ISD) makes the chips used in most of those cards. They probably use PWM to generate the audio.

Leon

Leon Heller G1HSM

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So is there a micro inside those cards? Or maybe a PWM generator IC?

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It isn't an MCU. See the Winbond web site for details of the chip internals.

Leon

Leon Heller G1HSM

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PowerSpeech series are popular in toys. It has an MCU, but it's absolutely minimal with no ALU and only 6 instructions or so and few registers.

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They are made by Winbond/Nuvoton, as are the ISD chips.

Leon

Leon Heller G1HSM