Mobile Mono Amplifier

Audioguru

Joined Dec 20, 2007
11,249
I was planning to incorporate a horn of some sort for amplification as was suggested earlier.
You can buy a horn speaker, they are used outdoors on a PA system. The horn matches its small vibrating part to the air better than an ordinary speaker and the horn directs and concentrates its sounds in one direction so it is much louder than an ordinary speaker.

So i guess i'll ask some more direct questions regarding the BTL app notes.

1.Why is there no ceramic decoupler on the BTL Vin. vs. the stereo setup?
The 0.1uF capacitor is missing. Use it because it prevents the IC from oscillating at a high frequency.

2. Why isn't there a single resistor used anywhere?
They are all built into the IC.

3. The app notes mention using a resistor to limit gain, where and how would that implemented?
To reduce the gain, add a resistor between pin 9 and the capacitor it shows on pin 9. It will probably oscillate at a high frequency if the gain is too low and they should tell you that.
The datasheet has an error on the BTL schematic because it wrongly shows pin 5 as pin 6.

4. not related so much to the schematic, but in a mono setup, I can see the input which I assume is the insulted wire contained in the 2 wire mono jack.
Where does the second un insulated wire connect? common ground w/ the power jack?
The insulated wire is for the signal and the shield is connected to the amplifier's ground.
Will you mix the input stereo channels together or just use one channel?
 

Thread Starter

luvv

Joined May 26, 2011
186
GRACIUS! Audioguru

After work Monday i'll tack the thing together see what i get.

As for your question,i hadn't really considered it, i assume the 5$ mp3 player is true 2 wire mono.
Guess i should wait till i see the actual headphones before asking the questions but..
are there any pros and cons to doing it either way?

Now should my workbench be graced by yet another puff of magic smoke,which isn't a uncommon occurrence w/ me.
Still want to build a amp for the experience of it if nothing else.
Buying solder by numbers velman kit just isn't anymore rewarding then buying a premade from the shack.
So any common bullet proof amp ICs out there you can recommend?

Thanks again Auidoguru, that was just the info i was looking for .

-luvv-
 

Audioguru

Joined Dec 20, 2007
11,249
All MP3 players I have seen play stereo, not mono.
I think your sounds will be recorded in mono so both channels will be exactly the same. Then use only one channel to feed your amplifier.

I know about many medium power stereo amplifier ICs for car radios. They don't work from a 9V battery.
I also know about many high power amplifiers for home stereos.
There are some low power class-D switching amplifier ICs made today but they are tiny and I can't see their pins (some have "bumps" underneath for connections).
 

Thread Starter

luvv

Joined May 26, 2011
186
All MP3 players I have seen play stereo, not mono.
I think your sounds will be recorded in mono so both channels will be exactly the same. Then use only one channel to feed your amplifier.

I know about many medium power stereo amplifier ICs for car radios. They don't work from a 9V battery.
I also know about many high power amplifiers for home stereos.
There are some low power class-D switching amplifier ICs made today but they are tiny and I can't see their pins (some have "bumps" underneath for connections).

Yea i have given up the 9v battery idea, instead ill opt for a 12v 3.2AH SLA
i got 6 of the things for my UPSs, they are small enough not to be a pain to carry.
If need be, i have gobs of voltage regulators, i can integrate one to suit the need.

Was looking at ICs from one of my fav random parts places, what do you think of this one http://www.goldmine-elec-products.com/prodinfo.asp?number=G15382

They are very on sale 14 for 10$ or perhaps one of the others they have listed?
 

Audioguru

Joined Dec 20, 2007
11,249
Toshiba is an international company. You would think that they would hire somebody who can speak and write good English to write their datasheet.

The IC has 4 bridged amplifiers and millions of pins. With a 13.2V supply it clips like mad at 18W with a horrible 10% distortion into 4 ohms or about 14W when barely clipping with low distortion per channel.

An audio power amplifier does not need a voltage regulator.
 

Thread Starter

luvv

Joined May 26, 2011
186
AG! (or anyone that knows)

So i figured out my layout, and started digging up components and discovered i haven't a single 150n cap anywhere.... plenty of 100n
and 222n..is there any real downside to substitute them?(marked in yellow on schem.)

And secondly, the input E- cap(marked in red) isn't it's polarity wrong?
All the amplifier circuits Ive looked at use a non polar type cap or am i just paranoid?

thanks again,

-luvv-
 

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Audioguru

Joined Dec 20, 2007
11,249
0.15uF (150nF) is a standard value. An Oriental film capacitor (green cap) will be marked 153.
There is no such thing as a 222nF capacitor so maybe you have 0.22uF or 220nF (marked 223) which is the same thing and it is close to the 150nF that is shown.
A capacitor marked 222 is only 2.2nF which is too small.

The IC is powered by the positve supply so its input is also positive and a volume control at the input of the 2.2uF input capacitor will be connected to 0V so the polarity of the input capacitor is correct.

You copied the schematic that has the pin 6 error because it shows two of them. I think one of them is actually pin 5.
 

Thread Starter

luvv

Joined May 26, 2011
186
0.15uF (150nF) is a standard value. An Oriental film capacitor (green cap) will be marked 153.
There is no such thing as a 222nF capacitor so maybe you have 0.22uF or 220nF (marked 223) which is the same thing and it is close to the 150nF that is shown.
A capacitor marked 222 is only 2.2nF which is too small.

The IC is powered by the positve supply so its input is also positive and a volume control at the input of the 2.2uF input capacitor will be connected to 0V so the polarity of the input capacitor is correct.

You copied the schematic that has the pin 6 error because it shows two of them. I think one of them is actually pin 5.
ok so i got everything ready now, care to have a look at my crude scribblings?
Don't have any of the polarities marked but i know now, see anything totally out of place w/ my interpretation of the schematic ?
 

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Thread Starter

luvv

Joined May 26, 2011
186
I get dizzy when I look at your skribbles.
You just need to know the key to reading them..

1. place forehead against your cane handle.

2. w/o removing the cane from the floor, spin 10 times clockwise

3.open the image,poof you can understand it :eek:

Nearly done now,we shall know soon enough.

If it don't work i shall emerse it in water and make HHO,never buy gas again!

Want a vid of it blowing up?;)
 

Thread Starter

luvv

Joined May 26, 2011
186
It's ALIVE!

Finished it up,it's no coyote caller but was a nice project for me anyhow.

Thanks to all whom suggested solutions, all of which would have been more suitable then my idea.

Big thanks to Audioguru for walking me through the chinglish data sheet and giving me straight answers.

AAC has to be one of the best resources for electronic DIY on the net,and i love it.

Watch the vid and feel the mono power of this lil beast..no really i filmed it w/ a digital camera not really intended for video so the sound is severely muted .

http://www.youtube.com/watch?v=SBnEsZnghN8&feature=youtu.be
 

Audioguru

Joined Dec 20, 2007
11,249
Nice going!
In the video I saw your tiny speaker's cone moving a little when it tried to produce 50Hz bass tones but it was actually producing 150Hz thumps. Cardboard box enclosure?
 

Thread Starter

luvv

Joined May 26, 2011
186
Nice going!
In the video I saw your tiny speaker's cone moving a little when it tried to produce 50Hz bass tones but it was actually producing 150Hz thumps. Cardboard box enclosure?
The box was used because the table is glass and would vibrate and rattle when i first tried it w/o the box .

It now resides in it own box complete w/ power switch and exterior gain control :)

Like i said before it's no coyote caller but at least it is a completed project and works as well as i could expect it to.

-luvv-
 

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thatoneguy

Joined Feb 19, 2009
6,359
It has enough fidelity and volume to be a coyote caller, especially if you replace the speaker with a horn.

You can get calling tapes everywhere, just digitize them and you are good to go.

I'd suggest using 6 AA batteries instead of a 9V for runtime, however.
 

Thread Starter

luvv

Joined May 26, 2011
186
For all i know about a speakers, i know even less about horns.

Care to suggest some?

I don't think my buddy would be satisfied w/ this one,it's nearly equal w/ the little electronic caller he gave me:(

Ive ordered some random amplifier ICs from goldmine, maybe ill take another run at a horned amplifier when they arrive.

Thanks,
-luvv-
 

Audioguru

Joined Dec 20, 2007
11,249
You do not need an expensive 50W(!) horn speaker.
There are many smaller, lower power, less expensive horn speakers available.
 
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