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I recently built the Bike Tyre Speaker and it really needed a little LM386 mono amp to boost the sound, as I wanted to 'Play It Loud'!

My fascination with electronics started from dissecting old electrical equipment just to see what was inside...

...beauty and intrigue...

...what are those bits...

...I started to learn how to put my own electronics together, building a LM386 amp as my second electronics project.

It really is a great little circuit for beginners to try.

For this project I wanted to capture some of that beauty within and what better than the vacuum tube as an embodiment of seeing the 'working' inside...

...the glorification of the humble into an aesthetic beauty.


This humble little amp build takes the aesthetic qualities of the vacuum amp to make an intriguing little object that is...

...great to look at, glowing red when switched on like a vacuum tube...

...the power source on show and easy to get to...

...and the on / volume knob made with a found object, an old bike derailleur jockey wheel to materially tie the amp to the Bike Tyre Speaker.

The two projects are made for each other!

Unfortunately the sound from an LM386 amp will never match the rich + warm tones of a vacuum tube amp, though if you ask me, if it looks this good, it makes it sound good as well!

Step 1: Design

My initial concept sketch caught the essence of the amp...

...a sweet little thing that would look great sitting on a display shelf just begging to be used.

The base of the amp to be a block of wood...

...a battery upturned and slotted in, to give prominence to this rarely thought about part of electronic equipment and easy to get to...

...an upturned spice jar to house the electronic circuit, a simulacra of a vacuum tube...

...that would protect and glorify the mighty LM386 amp circuit...

...an old mountain bike jockey wheel that I had kicking around that felt good in the hand...

...and two audio sockets, one at each end. The position of these would be changed due to space limitations within.

I have added the actual built sizes to the drawing of 55mm wide x 165mm long x 40mm high.

I would suggest that you test the layout and sizes before starting based on the parts and components that you have.

<p>I love it! congrats!!! Looks like this was the contest for 386 builders,</p>
Thanks Nizzy, the humble 386 ic did do well. I just wanted to make it look interesting, to make what's often hidden into something intriguing.
<p>Big thanks to all of you who voted for this project, joint first in the Amp + Speaker contest. Stoked!</p>
Excellent work! I wish you luck in the competition, as a judge, you have my vote!
Well thank you Bob, I'm excited to see how the project does though I think there are some very good projects in the finalist group. I really appreciate your support.
<p>That is wonderful! Were you able to mix in the &quot;hum&quot; that was so typical for valve-amplis? </p>
<p>Thanks Marc - The music for most of the video was the soundtrack from the Bike Tyre Speaker video as played through the speaker, the end soundtrack is the un-speakered soundtrack as in going through the amp.</p><p>The amp hasn't had any additional hum added than what it normally produces, in fact there is a little bit of the schematic that shows a couple of components for his suppression. I have used this to quite good effect in an electric uke that I have made, allowing the hiss to be switched on and off...I should get a video of that project made this winter.</p>
<p>Pura Arte.</p>
Thank you Arno.<br>
<p>Very nice to see this extensive work in the different fields of expertise.. You put a lot of time in making this handsome instructable, thank you very much for sharing!</p>
<p>Hey Wrrr, the great joy of this project for me was the bringing together of the different skills and materials, some completely new to me as with the metal etching. </p><p>It is great that it is getting so many views and I hope that the Instructable will help others to explore new ways to look at the projects that they create and or learn a new skill.</p>
<p>COOL :-)</p>
You are too kind Erwin!
I am glad to see experimenting with electronics.<br>I see from the comments that you want to try &quot;Tube&quot; circuits.<br>For your own safety I would recommend searching for 12Volt tube circuits to start.<br>There are many purpose designed 12volt plate voltage tubes on the market, also many tubes that were designed to work with 100 to 400+ volts on the plate that will work decently at 12Volts.<br>In 12 volt circuits you will not get hurt if you touch the wrong place with a finger.<br>When you touch the wrong place in 100 volt + circuits you can get badly hurt either from the Voltage or the normal reaction of JERKING away.<br>Try the low voltage first and grow to the high voltage,<br>When you get to the high voltage remember &quot;Always keep ONE HAND IN YOUR POCKET &quot;, and use &quot;Chicken Sticks&quot;<br>Keep at it and enjoy, you have talent in design I like.<br>These tips from a 70 year young person that learned the hard way.<br><br>Adrian &quot;46hammerman&quot;
<p>Good advice Hammerman, If I do eventually decide to make a proper tube amp I would go down the route of buying a kit from a reputable supplier, though in reality it will be a fair while before I gain enough experience to tackle it. Though many thanks for your advice.</p>
<p>What a beautiful work on the electrical parts layout. absolutely wonderful ! </p>
Thank you Ndjavla, the driving idea for the project was to glorify what is normally hidden, I would encourage everyone to break open old broken electrical equipment and see what is inside...often more interesting and visually engaging than the case!
<p>ver creative! Voted. But doubtful usage of the specific IC...low Watts. But its awsome</p>
<p>Agis thank you so much for your vote, very appreciated. Sure it is only a little amp, it is no more than a little 0.25 w LM386, though the aim was to make it something special.</p>
<p>I like your project and how the old tube look was built. Bravo sir Bravo. Those LM386 chips are amazing. So many circuits are built using them. Your attention to details is what makes it great. </p>
<p>GM, I really appreciate your kind words. You are right the LM386 is a great little chip and the circuit is a good easy one to make. </p><p>The op amp does have some limitations on the sound it will produce and will never have the tonal qualities of a real vacuum tube amp, though the project was to celebrate the circuitry and the beauty that is often hidden away.</p>
<p>Well I usually see that LM386 op amp used for quality headphone setups and not open air speaker driving. But the frequency response and THD levels are very good. It just doesn't have the wattage capability to drive speakers very loud. If you are looking for that capability you will have to go with high powered audio amp chips. But then you are talking about a more robust power supply and a preamp and tone control circuitry as well. So what you built is for medium level sound, but it should be loud enough with some quality as well. JMHO</p>
<p>Thanks GM - Its good to get some info from someone with technical knowledge.</p><p>Sure this is a little amp to boost a little speaker. </p><p>Good fun circuit to build and the project was great to make using lots of different skills.</p>
Great job. what would the power output of finished amp be? ie Optimal speaker spec?
<p>Thanks DBuckley - ooh technical stuff! I have to admit I am really very new to electronics and so far really only plug + play other peoples schematics. The LM386 is 0.25w so wont give a great deal of power I guess.</p><p>In use it is plenty enough for playing music through in a normal room setting. I will also use as a little practice amp+speaker combo for my electric guitar + uke.</p><p>The tyre speaker that I made previously used an old 0.25w 8ohm speaker if that helps.</p><p>Well worth checking out the Hack A Day link up in the description, which is where I learnt to build it. His video tutorial is really good and explains the electronics to a good level. In fact pretty much all I have learnt is through his site.</p><p>The concept of the project was to bring the interesting stuff that is normally hidden to the fore, and this principle could easily be applied to any electronic circuitry. I have an idea to make a stereo version maybe with another amp chip, if there is one, that will have two of the 'vacuum tubes'. The beauty of this project bizarrely is less about the quality of the sound and more about the aesthetics, though it sounds fine to me.</p><p>Sorry I cant help further though maybe others may comment and be able to give some more advice.</p>
<p>It looks very nice. I love your &quot;vacuum tube&quot;. Very creative.</p>
<p>Hey thanks Eric, I'm really pleased how it turned out, a lot of fun. I wished it sounded like a tube amp though maybe when my electronics skills have improved I may tackle building a real one.</p>

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