¡BUILD AN AM RADIO RECEIVER!
Introduction: ¡BUILD AN AM RADIO RECEIVER!
Hello my friends at Instructables, I hope you are having a good time meanwhile you are reading this, if it is not well... you need to put your hands to work in this AMAZING AM Radio Receiver Circuit, yeah! wanna get that almost free RF Radio waves from the air and to be listened by you ears?
Well... ¡it's showtime!
Definitely it is not a super regenerative or Heterodyne Receiver, not that kind of difficult stuff for many people who doesn't care about IF frecuency, AGC, RF filters, RF Cans, Decoupling Capacitors, Multiple Trimmers into a large capacitor and thing like that haha.
-And we don't use a all in one radio like the ZN414, MK484, TA7XXXX, one chip receivers in a TO-92 package, because in many places from the world is obsolete and hard to find :(
Plot twist:
-I tested this circuit and make some improvements on it. 485
to listen many AM radio stations near and not very near from your home, and IT WORKS!!!
-You can control the RF GAIN, make son BIAS to the transistors to listen stronger and clear the Modulated Amplitude Radio Waves, of course this is not a simple Galena radio, but it has a better performance :)
Lets get started!
Step 1: MATERIALS LIST
For this project we will need:
3X 2N2222A TRANSISTORS OR ANY NPN BJT TO92 PIN COMPATIBLE like 2N3904
1X 5K Potentiometer
2x 1N4148 Fast Recovery Diodes
1x Female Headers (at least 25 pins)
1X 104 (100 Nano Farad Ceramic Capacitor)
1x 103 (100 Nano Farad Ceramic Capacitor)
1x Knob for the trimmer or you can use a plastic point metal screw driver
1x MONO/STEREO Female Audio Jack
1x AA Battery Slot
1x 3K9 Ohm 1/2W Carbon Film Resistor
1x 2K2 Ohm 1/2W Carbon Film Resistor
1x 1M Ohm 1/2W Carbon Film Resistor
1x 4K7 Ohm 1/2W Carbon Film Resistor
1x Female Headers (24 pin at least) for Connections & Soldering
2x AA Battery (Alcaline, Carbon, NiMH etc)
1x RF inductor (Hand Made) i explain how to make the inductor in the next steps from this instructable
1x Variable Capacitor (Trimmer) 1-55 pF
1x 5 pin of male headers (not showed) for easy plugging the audio jack to female headers.
Utilities:
-Soldering Iron
-Solder 60/40
-Flux
-Breadboard Wire (it's recommendable to use 3 wire colors at least)
-Third Hand Tool or similar.
-PATIENCE :)
Step 2: HOW TO DO THE RF INDUCTOR (AM COIL)
This is an IMPORTANT step cause this component is critical for the correct working at the desired frecuency range between (550-1500) KHz, the Modulated Amplitude Signal on earth.
Let's go, is MANDATORY to use a Ferrite Core from about 0.8 Internal diameter, it's not necessary to use a cylinder ferrite you can use a planar ferrite like me, if you don't wanna go crazy finding this core, you can recycle someone from an old FM/AM receiver.
Well, let's continue. The internal diameter is about 0.8 centimeters of internal diameter, and about 58-60 windings of enamelled cooper wire of 30 AWG. (take it easy winding the ferrite core and do your best, nothing it's perfect).
-You can use a little bit of glue, tape, or anything you want to maintain the windings in the place), see the images above to have an idea.
-Once finished the winding and applied glue to the coil, it's mandatory to scratch the leads fo the coil to remove the aislant from the wire, and try measuring continuity to make sure there it is and the coil is formed correctly.
Step 3: Circuit Diagram (Schematic)
The circuit diagram shown in this step it's the complete and tested circuit. 996