hacking digital scale

Other Hardware Device Hacking
1

Hi,

Having been inspired by casainho's bluetooth-enabled scale (Google Code Archive - Long-term storage for Google Code Project Hosting.) I'd thought I would have a go at my own cheapo digital scale. However I've been having some problems identifying the components on the board. I'm guessing that the microprocessor is hidden underneath the black blob and that the 8 pin IC marked ISSI 546 406-26DL is an EEPROM. The real question is, what is the 14 pin IC marked AA|324 503BN (the logo is a swirly A)? Is it the op-amp? And in that case where can I find the datasheet for it? Can I assume that it is pin-compatible with an LM324?

Also I'm curious about the flat metal disc on the reverse side of the board, what is it exactly?

Thanks for your help!

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2

The 14 pin chip does look like an amp. I'd suggest setting your multimeter to voltage and probe the pins while pressing down on the scale. Or post a less blurry picture for suggestions on which pin is likely the output.

The flat metal disk is a piezo disk. In this case it is being used as a speaker to produce a "beep". https://www.google.com/search?q=piezo&tbm=isch

3

The 14-pin IC is a LM324, yes.

// Per.