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Best configuration for an AM receiver? Answered

Hi all. I am trying to make a circuit that would help me find lost keys. It would be a simple beeper/ noise maker triggered by AM (for simplicity). I want it to be small and, if possible, cheap. What would be the best approach? Should I use the incoming signal to 'trigger' a 555 oscillator or should I send the 'beep with the signal (The transmitter can be as big as required)? Also, most of the circuits I found online were for tune-able radios. If I want to center mine at 1 MHz and if the quality of the sound is not important, how simple can I make the circuit (while still keeping it sensitive)?


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6 years ago

Make transmitter and receivers is not easy. It requires some expensive equipments to help ensure the 2 are properly tuned so they will work together. Even with known good schematics, if you lay it out on a PCB wrong it will mess up the tuning. Something as small as the through hole size being too big can cause an issue.

Your best bet is to spend your money on one of the many existing products that do just what your looking to make. It will be cheaper in the long run. Here is one for less than $10.


If you want support for more sets of keys here is one for less than $22.