Making a radio as a beginner

Thread Starter

The_Logician

Joined Oct 2, 2023
12
I'm absolutely new to the field of electronics and am really interested in making a working AM radio. What radio would you suggest and where can I learn to make one(book/ site)?
Also it's preferable if the radio is powered as i do not have high impedance headphones
 

Ya’akov

Joined Jan 27, 2019
8,973
Welcome to AAC.

Do you need the radio to be portable, and practical for actual use or is the focus primarily on learning. If the latter than I would recommend the Elenco AM/FM Radio Kit. I have never seen a better radio kit for learning. In fact, we used this kit as part of an undergraduate university course because it offers opportunities to learn practice and theory, and includes a very good manual with explanations.

1701083892317.jpeg

The board is even laid out by functional block to make analyzing the circuit more straightforward. In the UG class it was part of, the final was based on the student’s ability to identify the function of a component or group of components in a given stage, and describe the effect of an incorrect value for one.

It can take you very deep into not only radio but circuits, and of course, it is very good training/practice for soldering and PCB assembly skills. As you can tell it is not a practical portable radio, but it will work on a tabletop. Even if you want a portable radio, I would start with this kit because you can gain so much from it. If it fits your budget, I wouldn’t hesitate—it’s one of those hidden gems.
 

SamR

Joined Mar 19, 2019
5,019
It's pretty simple to put together a "crystal" radio with an LM386 amplifier to speaker. Build a coil, buy an air gap capacitor to tune it, buy a germanium diode, and put it all together with an amplifier and speaker. Then get into transistors. There are even AM/FM radio chips and the MK484 in a TO-92 package AM radio.
 

Thread Starter

The_Logician

Joined Oct 2, 2023
12
It's pretty simple to put together a "crystal" radio with an LM386 amplifier to speaker. Build a coil, buy an air gap capacitor to tune it, buy a germanium diode, and put it all together with an amplifier and speaker. Then get into transistors. There are even AM/FM radio chips and the MK484 in a TO-92 package AM radio.
This is preferable to me as I'm trying to make one from scratch not a kit. I have made the crystal radio with an N34 diode and a parallel LC circuit but I have no idea of how to use the amplifier. Will a LM358 work?
 

MrChips

Joined Oct 2, 2009
30,488
A crystal radio begins with a good aerial and a good ground. Do you have both of these?

Then you need a germanium diode such as 1N34 and a high impedance earphone or headset, at least 5kΩ.

Here is your simplest working crystal radio:


1701094176955.png
 

MrChips

Joined Oct 2, 2009
30,488
The next step is to include an LC frequency resonant stage.

1701094386235.png

This is my basic DIY crystal radio. The coil is wound on a cardboard tube from a toilet paper roll.
I am using only one section of the variable capacitor.

1701094418713.png
 

MrChips

Joined Oct 2, 2009
30,488
You can improve the selectivity by lightly coupling to the LC resonant circuit using an additional coil.

I made the coil with the original toilet paper roll. Then I used another cardboard tube for the second coil that slides over the original coil. In this manner, I can adjust the coupling between the two coils.

This circuit shows the modified LC input stage. The AF amplification is also shown.

1701097019455.png
 

Audioguru again

Joined Oct 21, 2019
6,610
I have no idea of how to use the amplifier. Will a LM358 work?
An LM358 is a dual opamp. It and most other opamps have a very low output power that cannot drive a low impedance high current speaker. A power amp is needed to drive a speaker. An LM386 is a little power amp (1/2W into 8 ohms when powered from a new 9V battery) like a cheap clock radio.
 

Ya’akov

Joined Jan 27, 2019
8,973
The simplest circuit uses only one transistor, one capacitor, and one resistor:

1701162512972.jpeg
If you need more gain you can use a second transistor which makes it only a little more complicated.
 

Audioguru again

Joined Oct 21, 2019
6,610
I never had a class-A amplifier/home heater. My first audio power amplifier was a class-AB Heathkit with vacuum tooobs and all my transistor and IC power amplifiers were also cool class-AB.
 

Audioguru again

Joined Oct 21, 2019
6,610
My cars never used vacuum tooobs in their radios or amplifiers. The engine's coolant heated the car's interior.
All the amplifiers were class-AB but maybe the newest one is class-D.
 
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