Can anyone tell me what kind of a chip is used to detect signals in the air?
I've figured out that the chip used on the cellphone keypad responds to certain frequencies. So far I've noticed that the LEDs connected to the keypad all have constant power, when the chip picks up the signal it simply closes the connection to ground for each line. Just wondering where I could pick up such a chip and what it's called.
I've figured out that the chip used on the cellphone keypad responds to certain frequencies. So far I've noticed that the LEDs connected to the keypad all have constant power, when the chip picks up the signal it simply closes the connection to ground for each line. Just wondering where I could pick up such a chip and what it's called.
