The following is a collection of radio receiver designs which use the popular MK484 "radio on a chip".
This device is a 3 terminal (TO92) package; which has only in/out/gnd terminations.
See manufacturers data sheet for further info.
This is a radio of my own construction in which I managed to fit all componentry into a small (recycled) plastic food container.
It is one (NiCad) cell powered and will fit in your shirt pocket.
This elegant design from Darren Yates sited in Australian "SILICON CHIP" magazine, and is as good as you'll find. It is similar to my "Cigar-Box" radio shown elsewhere.
This is a "breadboard" construction MK484 based receiver, circuit being very similar to Darren Yates "Weather Radio".
I was trying to experiment to see what effect, An RF gain control, variation of chip supply voltage (0 to 3 volt) and altering the LC tuning (in order to tune higher than Broadcast frequencies) would have.
Some info floating around the internet would suggest that the MK484 may work in the 80 metre and possibly the 40 meter amateur band assignments!
I found this to be completely untrue as these chips will only function below about 3 Mhz effectivley.
The manufacturers frequency plot will affirm this fact.
Notwithstanding the above; this is a regenerative MK484 design I found on a (Dutch) website.
I haven't constructed it, but it purports to be able to tune up to 7MHz by using a regenerative transistor input stage to obtain the necessary sensitivity.
Seems like a good idea, but only a working model would reveal its real potential!
Here is another good VK3XU design which uses the MK484 as a fixed frequency (470KHz) I.F. amplifier.
Ingenious; as the MK484 contains about 10 active transistors incorporates several RF stages, automatic gain control and an AM detector.
I have not tried anything like this, however a functioning demonstration on YouTube of the design is at: