FM reciever with LM386

This coil is home-made. It is actually a single layer 'tapped' air core coil. Please refer to my special section on how to make the DRAIN Coil. Once it is made, the tapped leg goes into the middle hole (Refer to CHART I), but make sure you have the coil positioned so that the tapped leg is closest to the .001uF ceramic capacitor. You will have to bore out the tapped hole on the PCB a little in order for the tapped leg to fit. Then solder into place. Start with a two turn tap. If the unit responds well to this, you may want to increase the overall sensitivity of the unit by making a three turn tap. The tap is always closest to the .001uF ceramic disk capacitor.

In this project, a home-made air-core coil is utilized as a crucial component of a one-transistor FM receiver circuit. The coil is constructed as a single layer tapped air-core type, which allows for the adjustment of sensitivity based on the number of turns in the tapped section. The design requires careful positioning of the tapped leg in relation to a .001uF ceramic capacitor, which is integral to the tuning and performance of the receiver.

To create the tapped air-core coil, the construction involves winding insulated copper wire around a non-conductive cylindrical form, ensuring that the coil remains a single layer. After the coil is completed, the tapped leg must be inserted into a designated hole on the printed circuit board (PCB). It is necessary to modify the hole slightly to accommodate the tapped leg, which is crucial for achieving a secure connection.

The initial configuration involves a two-turn tap, which serves as a starting point for sensitivity adjustments. If the receiver exhibits satisfactory performance, the user may opt to enhance the sensitivity further by adding a three-turn tap. The proximity of the tap to the ceramic capacitor is essential, as it influences the resonant frequency and overall functionality of the FM receiver.

This project not only introduces the construction of the coil but also provides an opportunity for experimentation within the VHF (very high frequency) range. The knowledge gained from this hands-on experience is invaluable for understanding the principles of radio frequency transmission and reception. The project encourages further exploration and experimentation, fostering a deeper comprehension of electronic circuits and components.his coil is home-made. It is actually a single layer 'tapped' air core coil. Please refer to my special section on how to make the DRAIN Coil. Once it is made, the tapped leg goes into the middle hole (Refer to CHART I), but make sure you have the coil positioned so that the tapped leg is closest to the .001uF ceramic capacitor. You will have to bore-out the tapped hole on the PCB a little...in order for the tapped leg to fit. Then solder into place. Start with a two turn tap. If the unit responds well to this...you may want to increase the overall sensitivity of the unit by making a three turn tap.

The tap is always closest to the .001uF ceramic disk capacitor.

In this exciting project, not only will you have a very unique one transistor FM receiver, but also be in-store for making home-made air-core coils. And even more than that, when you finish 'your' project, your journey has just started. With your now-working FM receiver, you can start experimenting with many wonderful things that I had mentioned above.

Once you have mastered all these things...you will surely have a better grasp on the whole concept of what 'hands on' experience truly is...not to mention you are doing all of this experimentation way up in the VHF (very high frequency) electro-magnetic spectrum. It is a very rewarding experience when you have gone into the unknown...taken roads that you have never taken before...roads that lead you to knowledge of things that you would have never thought possible...and all on your own!

Throughout this website, you will also find other nice projects.

Some by me and some by my good friend...Pedro. We have put all these wonderful projects out to you in hopes that...just like fishing, if you have never experienced the joy of catching your first fish...you will never know what its' like. The same goes for these projects... we have all the 'bait' here for you to take...but it will be left up to you to grab it. Every so often I go and post my Radio Shack Special to as many radio/ham/electronic forums as I can..not to mention always updating the website from comments, questions, concerns or advice from recent guests.

Pedro and I are glad to see that you have managed to get here. With all that said, continue the voyage into the wonderful world of the single and proud...MPF102 transistor.

 

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