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Fido's out of the doghouse now, thanks to Larry's automatic mail delivery notification system. When the postman opens the lid of Larry's mailbox, a photodetector mounted inside the mailbox activates a light-emitting diode inside the house, notifying him that mail has arrived. A special latch circuit ensures that the LED stays lit after the lid shuts, and a pushbutton allows Larry to reset the circuit after retrieving his mail.
Are you a Gadget Freak? Allied Electronics would like to send you on a shopping spree of up to $500 on its website at www.alliedelec.com/gf.asp. Email Design News your proposed project (must incorporate electronic components and involve sensing, motion, timing, and/or networking elements) to [email protected], along with a description of how it works, and a parts list. If your project is selected, you'll receive the shopping trip of up to $500 and be featured in an upcoming edition of Design News.
| Mail's Here! Parts List | ||
|---|---|---|
| Amt | Part Description | Allied Part # |
| 1 | Ceramic Capacitor, 1.0 muF | 881-5236 |
| 1 | Ceramic Capacitor, 0.1 muF | 881-3486 |
| 1 | RED LED | 670-1065 |
| 1 | NPN Transistor | 935-0841 |
| 1 | CdS Photocell | 980-0105 |
| 2 | Carbon Resistor, 22 k | 296-6330 |
| 1 | Carbon Resistor, 1 k | 296-6314 |
| 1 | Carbon Resistor, 10 k | 296-6326 |
| 1 | Carbon Resistor, 1 meg | 296-6348 |
| 1 | Normally Open Pushbutton | 757-2305 |
| 1 | CD4011 Quad NAND | 735-1323 |