Cycle music

The theme of portable audio on a bicycle often becomes relevant after regular rides. Riding a bike with a group of alkobikers of familiar faces is not like meeting in itself. Most of the way, everyone is silent. From the monotonous pedaling and the relatively poor nightly variety before our eyes (after all, we work during the day and ride in the evening), something called desire becomes boredom. Boring for a long time monotonously silently pedaling, lonely. Which exit?
“Everyone sees only what is already in him” - do not consider this article as a guide to the theft of the silence of a neighbor. No one has done this, and is not going to.
We need a connecting element - music. If you listen to her, you know what your neighbor is listening to. Instead of the impossibility of speaking, we get the opportunity to listen. Do you often have moments in life when all people listen and are silent? (minibuses with a radio do not count, there the driver gives his ears to the radio station, apparently out of fear of not knowing what to do with them). Therefore, it is very important to listen to what you really consider necessary and thoughtful. Something I'm not talking about.

I met commercial systems in the form of a flask (1), boxes on the steering wheel (2), and a promotional project of some designer (I don’t remember my name, but actually I came up with it before)) in the form of a backpack with columns (3), trailers ( 4). All of them are quite expensive and low-power (except for trailers naturally).


I assembled the first simple amplifier on a microcircuit according to the scheme from Radio magazine about 5 years ago.
I didn’t have any concepts about the efficiency, types of amplifiers, output power, input overload. I knew that the 12V input should give "quite loud."

Task

And so, to create a portable cycle music, we have to decide, in a village way, what we want to have at the exit:

Loud, light, with high efficiency (so that it would be enough for the night), connected to a pocket player (phone).

Russian language:

1) Player / Phone
2) Amplifier
3) Speaker
4) Power source

1) Player

Anyone will do it! which has a headphone output.

I am using a Zune 4GB player. I would like to have a player with a higher output signal, I feel I can not squeeze out all the juices from the amplifier. From experience, I’ll say that it’s not convenient to hold the player in your hand on a bicycle with a cord. I wanted to replace the player-amplifier bundle with a jack-RCA wire over my shoulder with a system on bluetooth, but it requires additional attention with power.

2) Amplifier

There are approximately the following types of audio amplifiers: A, B, A / B, C, D, G, H, T ...
You can read about them elementary, here's what is important to know:

Amplifier Class “A” is considered the highest quality. Efficiency is usually 20%, yes it is a heater. Without a radiator, microcircuits are usually cut down immediately. The transistor operates in open mode: it amplifies both the negative and positive half-wave signal. At the same time, he eats in idle as much as at maximum.
This does not suit us.
Amplifier Class “B”
Its advantages in a relatively high efficiency (50-60%). One transistor amplifies the negative, the other - the positive side of the half wave. At the moment the signal passes through zero, significant sound distortions appear.
This does not suit us.
Amplifier Class “AB”
Naturally, electronics are cubes, we take yes and combine the two classes listed above, we take from each of the advantages. Amplifiers of this class are the most common.
Already better.
Amplifier Class “D” (close class “T”)
This is the last class I will talk about. The rest are too rare and not necessary.
The basis here is PWM modulation. Due to the fact that the transistors operate in a pulsed mode, the efficiency tends to a very good figure from 80% to 98%! Accordingly, there is no need to remove heat, the dimensions of the amplifier are significantly reduced. With the sound, too, everything is in order.
This is exactly what we need.

I walked through the catalogs of audio amplifier microchips. Found a wonderful TA2024.
But due to the relative complexity of finding capacitors, inductances and making a circuit board, I decided to buy this miracle from the Chinese. As I was happy - they also read the Habr these directories and were unanimous in choosing an amplifier heart.



Board manufacturer's store - Sure Electonics . Quality 5 points. Price $ 17! They sent all the screws, clamps and wires. The quality of the latter is really terrible. There are several duplicate connectors on the board. You want to hold the wires, you want through the tulip.

Specifications:

• Class-T Architecture
• Input Voltage: 12B
• 15W Watts per channel (4Ω, 10% THD + N)
• 10W Watts per channel (4Ω 0.1%, THD + N)
• Efficiency> 88% when fully powered (RL = 8Ω)
• No radiator needed!
• MUTE and SLEEP modes
• On-click protection on shutdown
• Short circuit protection
• overheat protection
• Works with any 4 / 8Ω speakers
• Input any standard signal
• Two-layer installation, which reduces the cost of the product
• Over 90% of SMT components (very small)

Why connect it?

3) Loudspeaker

Frankly, I’m not a fan of reading how many ohms the winding from the speaker on my ancient music center (1 speaker is 3 ohms, another 8 ohms). I did not want to look for another loudspeaker - I do not know where to find another one as light and small. You will feel very well what a sound corridor is and the most amazing sound will certainly be in the tunnels and under the bridges.

4) Power

Since I am lazy, I use a 12V 4.5 Ah lead battery (which are in UPS, although more often there are 7 Ah). Two Li-Po 11.1 V. 2.5A / H lie. Weighing 300 grams, but this is not for us.


How much battery is enough?
I don’t remember the volume levels before and after the trip (4-6 hours drive). It’s hard to compare. The sound is getting a little quieter. But enough for the night with his head.

Use experience

1. Health
   Nevertheless, I do not recommend carrying the amplifier for a long time. This option is the easiest, but rather exhausting. After 50 km, any little discomfort before will turn into a callus after. In the backpack between the back and the column, I usually put a sheet of trapik in shape (tourist trapik, foam) for greater comfort. The battery rests against it. I love a dry back, I don’t like backpacks, but I can’t refuse friends to alkobikers . Have to sweat.
   
2. Usability
   All this stuff described above is placed in a backpack empirically. You need a backpack with a thin back wall so that the sound does not go out. (I usually open my pocket) The
   usability of this system depends on the flexibility of the player’s cord and the place where the player fits and gets without any problems. (some kind of pocket) Ideally, of course, attach it to the steering wheel and refuse the wire. Broadcast via bluetooth to the amplifier.
   I can’t say the exact weight of the system, around 3kg.
   
3. Environment
   There is such a pollution factor - noise. Honestly, I can’t understand why there are “chrome” exhaust pipes with increased “volume” on sale. The car has a guest in terms of noise, it does not have to undergo inspection with a new "improved" exhaust pipe. This is more important than the glass for which people hide their affairs. We have so much noise that you need to respect the streets you ride on. Even the forest, when you get into it, it seems like you will get revenge for loud music.
   In the forest, I make fun of and put the singing of tropical birds, the eyes of the people roll out on his forehead, where are the birds from here)
   
4. Electronics
   Players are falling out of hands. Simple cheap cords between the player and the amplifier in the backpack are bent, after a month of other trips from vibrations there is a chance of a broken wire in any running place.
   It is better to take a spare RCA jack wire.
   
5. Society
   Listen to people quietly, usually not everyone shares the work of the “night whim” studio and A. Razembaum’s album “On the Plantations of Love”.) No matter how you mess with him, it’s impossible to love forcibly.
   The only step is to tell about him by the fire, if you want to share what he hurt you so, do not be silent).
   I had an idea to put audio books ... but this is on extremely long trips, when you can be silent for hours.
   

Conclusion and Ideas

Unfortunately, I did not find a normal video from the pokatushka, where you can listen to the volume of the system. The goal was not to wake someone at night or to interfere with someone. A stereo amplifier, one speaker - therefore, the sound is mono. My next find was in broadcasting the second channel on the radio to a second bike with an amplifier! The second person does not have a player, only a radio. He takes the left channel from my player, and I drive the right. As a result, we have full stereo. Moreover, since we have a transmitter for a second bike, why not take this signal to everyone else, but not to the amplifier, but to the light music?

Imagine a spectacle: a gang of cyclists rides with music, while the rest beats light to the beat. If there were many of us, if it were worth it, I would do it. And on this note I say goodbye.

PS.
Found on this chip an amplifier on dealextreme