How To Make An Amplifier From An Old Radio

Learning how to make an amplifier from an old radio is an interesting DIY project. Do you have an old radio sitting and gathering dust on your shelf? Don’t discard it yet! You probably didn’t know you could make an amplifier from your old radio, did you? In this article, you’ll find simple and detailed steps on how to make an amplifier from an old radio. Even if you don’t have an old radio, you can get one from a thrift shop in your locality and convert it into an amplifier.

What Is an Amplifier?

An amplifier is an electronic device that increases, enlarges or strengthens electronic signals. An amplifier receives a small or weak input signal and responds to it by delivering a stronger output signal while maintaining the essential features of the waveforms of the input signal. The amplifier does no other alteration to the signal received as input other than to increase or strengthen and then release the expanded signal as its output.

In addition, there are different types or categories of amplifiers. This categorisation is based on the size of their signal, how their circuit is configured and how they operate. In other words, the class an amplifier belongs to depends on how large or small the input signal it receives is. It also depends on how it processes the signal it receives as an input. Lastly, it depends on the input signal it receives relates to the current load.

Simply put, an amplifier is a simple box. This simple box contains the amplifying device which may be a bipolar transistor, a field-effect transistor or an operational amplifier. The amplifying device has two input terminals and two output terminals. The input terminal is used to receive the input signal while the output terminal is used to deliver an expanded version of the input signal.

What Does an Amplifier Do?

An amplifier receives a signal from a source, boosts it and delivers the boosted input signal as its output signal. The amplifier maintains the quality of the input signal therefore, the bigger the input signal, the larger the rate at which the output signal is increased. This is a dummy explanation of what an amplifier does.

Apart from the fact that amplifiers boost the input signal and release a larger output, they also ensure that the quality of the input signal is maintained and not distorted. The implication of this is that amplifiers do not only boost the strength of the input signals they receive, they also maintain the quality of the input while giving out an increased output signal. When this is not effectively done, we have what is called distortions feedback or frequency response.

Amplifiers in hearing aids make voices sound louder. In radios, they strengthen signals that are far away so that it becomes easy for such signals to be picked up. They are found in many electronic devices.

The difference an amplifier makes is called the gain of the amplifier, measured in decibels(dB). Calculating the gain of an amplifier is simple, it is the ratio of the output signal to the input signal. For example, if an amplifier increases the size of its input signal threefold, it is said to have a gain of 3.

How to Make an Amplifier From an Old Radio

Now that we’ve explained the basic stuff about what an amplifier is and how it works, let’s dive into actually learning how to make an amplifier from an old radio.

Learning how to make an amplifier from an old radio is a straightforward recycling DIY project that gives you an amplifier with a unique sound of its own depending on the kind of radio you choose to use.

This DIY project not only saves you the money you would have to spend to purchase an expensive amp, but it also ensures that e-wastes are drastically reduced in the dumpsters. Recyclable materials are being recycled, mother nature is happy and your pocket is happy too. It’s a win-win for all.

Homemade simple black audio amplifier with bluetooth.

What Level of Experience Do You Need to Make An Amplifier from An Old Radio?

A beginner or intermediate level of experience is enough to make an amplifier from an old radio. You need to at least know your way around electronics and have a basic knowledge of parts and all.

If you have never built or worked on electronics before now, you might have to go slower than someone who has a pretty decent knowledge of how electronics work.

However, if you follow the procedures and steps as outlined, you should be able to cope fairly well. It is doable if you’re determined to make it work.

What are the Tools You Need to Make An Amplifier From An Old Radio

The very first step to take in making an amplifier from an old radio is to gather the tools you would need. The following are the tools you need to make an amplifier from an old radio:

An Old Radio
A Soldering iron
A roll of soldering wire or any adequate supply
22 AWG silicone wire
One-quarter-inch mono female jack
Phillips head screwdriver
Flathead screwdriver
Scissors (or any safe tool to cut your wires)
Guitar & instrument cable
Drill (if you have one, if not, you may do without)

This is a simple list of the essential tools you would be needing to make an amplifier from your old radio. You can substitute with safe alternatives where necessary.

How Long Does the Process of Making An Amplifier From An Old Radio Take?

You may be wondering about how long it would take you to build your amplifier from an old radio. It depends on some factors.

Your supply of tools
Your dexterity in working with and around electronics
The type of radio you’re using
How busy you are or how much time you can set aside for this project and see it to completion.

With the factors stated above taken into consideration, the time it would take you to build an amplifier from an old radio depends on you and your circumstances.

That being said, ideally, it should take you between 2 -36 hours (including the time it would take to order your supply) to have your new amp ready and blasting away.

What is the Cost Implication of Making An Amplifier From An Old Radio

One other question you may be asking right now is how much it would cost to make an amplifier from an old radio.

As noted earlier about the time it would take, the cost of the project depends on you and some factors.

If you already have most of the tools you’ll be needing at home, you wouldn’t have to spend much. However, if you’re ordering everything you need from scratch or most of the tools you’ll need, you would be spending much more than if you had everything you need at home.

Also, if you’re buying from a thrift shop or junk store, you might spend less than if you’re buying from a state of the art electronic store.

Overall, you shouldn’t spend more than $100 to purchase all the tools you’ll be needing to build an amplifier from an old radio. The less purchase you have to make, the cheaper the whole thing will be.

7 Simple Steps To Follow to Make An Amplifier From An Old Radio

Making an amplifier from an old radio can be as easy as ABC. Simply follow the outlined steps below and you’ll be blasting away with your amplifier in no time

1. Choose Your Radio

The most important tool needed for this DIY project is your old radio. This is the very first thing to pay attention to and settle.

As important as this step of the procedure is and as much as you need to pay serious attention to your choice, it is one of the easiest things to do.

You can get a good old radio at your local thrift shop at the junk store or simply order one online. At this point, you should pay attention to the features you consider important. Do you want to have good control of your sound? Then you should go for an old radio with control knobs for tone, frequency, equaliser, squelch, etc.

On the other hand, if you want your amplifier to be a handy travel companion, then you should go for a radio that is battery powered or one with a headphone jack or even one with a built-in handle.

Furthermore, the type of radio you get could either make the process of making your amplifier safe, easy or complex, tortuous and dangerous. It is safer to use old tube radios. Look out for information about the radio at the back of the radio. Old radios usually feature this. You may find a list of the names of the tubes used in building the radio at the back of it. Avoid Allstrom units as they can be very dangerous to mess with.

Finally, ensure your radio is in perfect working condition.

There, you’re good to go!

2. Gather All the Needed Tools

Now that you’ve carefully selected your radio, the next thing to do is to collect every other tool you’ll be needing. Nobody goes to work without the necessary tools? You need to gather all the tools you would be needing to make an amplifier from your old radio. The tools you’ll be needing have been stated above. Collect them all, set out your tools and get down to work.

3. Open up Your Radio

You’ve got the right radio and you have all your tools set out, the next thing is to open up your radio. You need to do this as carefully as possible.

Remove the knobs and switches first. Then unscrew the outer casing of the radio. Check the corners of the radio and the space under the battery holder for some of these screws. Once all the knobs and screws have been removed (you’ll be needing your flathead screwdriver or any flat material here), pull your radio apart. Do this as gently as possible.

4. Locate the circuit board of your radio.

Once you have the old radio opened up, you need to locate the circuit board of your radio. It may be flipped over or you may find it protected in a casing. In that case, you would need to unscrew it.

5. Prepare the quarter-inch jack

Cut some pieces of wire. Let it be of reasonable length, neither too short nor too long. Then you need to strip the two ends of the wire to expose them. You can use scissors or a wire cutter or stripper to do this.

Once you have your wires stripped, the next thing is to solder the wire onto the jack. Your jack has two pieces sticking out across each other. They are called solder lugs. One is connected to the middle of the jack and is not as long as the other while the other is sticking out and a bit longer than the other. The shorter part of the solder lug is called the sleeve. It is meant for your ground wire. The longer part of the solder lug of the jack is called the tip and is meant for your hot wire. Select any of your wires to serve as your ground wire and solder it onto the centre lug of your jack while soldering the other onto the outer lug of your jack. The one soldered to the outer lug serves as your hot wire.

Viola! Your jack is prepared and ready to serve its life purpose!

6. Locate the Volume Pot on Your Circuit Board

Your jack is ready and raring to go but where do you plug it? You need to locate the home of your jack on your circuit board. The piece you are looking for is called the volume pot. The volume pot is what the volume knob of your radio is connected to so it should be pretty easy for you to locate. It also has multiple solder lugs; this should help you recognise it faster.

Here’s a tricky part of the whole process. You need to find out which lug to connect your wire to. This is tricky but not herculean.

First, plug your instrument into your jack. Then, find a negative point to solder your ground wire to. Use the negative point in the battery terminal. Solder your ground wire to this point. Then power on your radio.

What you need to do next is find the sweet spot for your hot wire. You want to find the exact lug that amplifies your instrument and works with the volume knob.

Place your hot wire on each lug while playing your instrument until you find the lug that fits the description above. That is the lug that not only amplifies your instrument but also works perfectly with the volume knob of the radio to control the volume of your instrument. Once you’ve found the lug, turn your radio off and solder your wire onto the lug.

You now have a working amplifier!

7. Put Your New Amplifier Back Together

Your amplifier is now working, you need to put everything back together.

Find a suitable spot for your jack, ensuring that it has enough space without interfering with other parts from the circuit board. You need to also ensure that the casing would close up properly.

Cut a hole into the casing of the radio that would be of adequate size to accommodate the tip of your jack. You may use a drill or any sharp object to make the hole.

Remove the washer and nut from your jack and fit your jack through the hole. Reattach the washer to ensure your jack is sitting perfectly in its place.

The next thing is to reattach the circuit board and its casing or cover if you had to remove them. Then close up the radio and fit back all the screws you removed when you started.

There, you have your new amplifier!

Find an easy and detailed video tutorial below.

How to Make an Amplifier More Powerful

Amplifiers have limits. There is a limit to how much an amplifier can boost a weak signal while maintaining the quality of the input without distortions or clippings.

Clipping happens when an amplifier produces the same level of output even with increased input.

A way around this is to simply connect more than one amplifier. In this case, the first amplifier receives the input signal and boosts it and then delivers it to the next amplifier. The second amplifier would receive the output of the first amplifier as its input and then boost it further before delivering the now powerfully boosted output. This chain is continued until a sufficient amount of boost needed is achieved.

Moreover, some devices use more than one amplifier, mostly two different amplifiers. The first amplifier is referred to as the pre-amplifier while the second is the amplifier. The pre-amplifier receives the input signal and boosts it into a minimum level of input for the main amplifier. The main amplifier then receives the boosted signal to something large enough to be delivered as output. Some MP3 players work this way.

FAQ’s of How To build An Amplifier From An Old Vintage Radio

Are older radios better than newer radios for conversion into amplifiers?

It all depends on what features are more important to you. If you want your amp to produce low-fidelity or vintage tones, then old radios are your best bet.

If, on the other hand, portability, a more beautiful outlook, or a cleaner tone appeals to you, then you should use newer radios.

Should I unplug the amplifier before making changes to the system?

Of course! You’ll have to unplug the amp from the source of power whenever you need to make some changes in the system.

This is particularly advisable if you didn’t connect an antenna to the system. This will help prevent some handful of damages to your amp.

Do amps function on cell phones?

Yes. Some amps can work in concert with all digital and analog GSM technologies, such as TDMA, CDMA, AMPS, EDGE, iDEN, 3G HSDPA, GPRS, and the latest1xEV-DO.

Can a direct connection amp be used as wireless units by including inside antennas?

Direct connection amps are ought to be physically linked to your data card or mobile phone with an exterior antenna adapter.

It does not generate sufficient gain to power an internal antenna and provides you with even a tiny service range.

Can I get greater power outputs by paralleling amps?

Yes. But the truth is that it is not as easy as linking both outputs and both inputs in a parallel arrangement.

It entails a thoughtful utilization of power hybrids with appropriate power levels, phase balance, and amplitude, together with amps well-matched for phase and gain characteristics. Examples of these are the MERA and HELA-10 amp series.

Conclusion

Making an amplifier from an old radio is a very simple and interesting DIY project. You don’t need a degree in electronics to be able to pull it off. Whether you use an old radio or a new radio depends on what you want. Neither is better.

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