text on mystery IC

I found an old board in my stash which seems to be from a smoke detector. Trying to convert it into a doorbell I can hear way out in the yard. I tried Googling the numbers marked on the IC but I can't find anything. What I know so far is that the IC seems to be in a DIP-14 package, top is marked with a Motorola logo although the manufacturer prefix tend to indicate it is from Phillips. Pins 1, 3, 10, and 13 are not connected. Pin 2 is raised upwards as if there used to be another connection to another board at some point. Does anyone know what this IC is? A datasheet would help a lot. Thanks here is a top view of the board here is a bottom view of the board

  • \$\begingroup\$ The chip seems to be from 1978, so good luck... \$\endgroup\$ – Ale..chenski May 18 '19 at 20:11
  • \$\begingroup\$ And +1 for exemplary picture quality. \$\endgroup\$ – Ale..chenski May 18 '19 at 21:15

It's almost certainly a proprietary part, probably an application-specific smoke detector chip. The part number would either be dictated by the customer, or cooked up in cooperation between Motorola and the customer.

Smoke detectors are small, high-volume, and at least moderately high-tech; this is a combination that leads to ASICs.

For the purpose of making a loud noise, I suspect you want to look at the sounder and the transistor that's just below it in the component-side view. I suspect that the chip just applies power to that circuit, or possibly bias, or a square wave applied to the transistor base.

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