i have been looking at a number of different ways to make a heterodyne bat call detector. one that intrigues me is the use of an am reciever ic. i understand the principal of using the oscillator and the mixer on the ic, to shift the frequencies of the bat calls down to an audible (for us poor humans) level. i was looking at a particular chip, the TDA1220B (datasheet attached), but cannot work out how to use it. i have found a circuit that uses the TCA440 am reciever ic, but simply copying someone elses circuit doesn't help ,me understand how it all works.
so if anyone can help me to configure the TDA 1220B, i would be very grateful.
i need to control the oscillator frequency from about 10khz to 100khz, feed it into the mixer with the bat signal which will either be from a 40khz tranducer or an electret mic such as the MCE2500, and take the output to amplify and then to a small 32ohm speaker.
the reason for this particular idea is that it requires so few parts as the oscillator and mixer are both within the single ic.
so if anyone can help me to configure the TDA 1220B, i would be very grateful.
i need to control the oscillator frequency from about 10khz to 100khz, feed it into the mixer with the bat signal which will either be from a 40khz tranducer or an electret mic such as the MCE2500, and take the output to amplify and then to a small 32ohm speaker.
the reason for this particular idea is that it requires so few parts as the oscillator and mixer are both within the single ic.