which low voltage portable IC amplifier

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Hi all,

I hope one of you guys can help me. I need to build a protable amplifier, battery powered, about 4 watt maximum output power.

For this I selected to use 6 x 1.5Volt pentlite batteries and the TDA7266 IC amplifier. However, I cann't seem to buy this IC in my country (The Netherlands).

Can someone suggest another IC?

It needs to run on low-voltage (from about 6.5 volts), and must not drain the batteries, so low Iq), and prefferebly drive the 8 Ohm load in bridge mode.

Greetings from The Netherlands,

Thijs
 
Hi Jackini,

Thx for your suggestion. I noticed however that the Nat Semi IC seem to be suited either for 5.5Volts max or 10Volt minimum (1 exception).. which is just the area I looking for.

I have looked into 39 different IC now, from Philips, ST electronics and Nat Semi, I cann't seem to find a really nice one.

It should be that difficult, 7.5 V min, be able to drive 4 Ohm or 8 Ohm bridged and give about 4 Watts...
 
I'm not too familiar with TDA7266, but LM386 is perfect for your application. It is a DIP 8-pin package.

I remember long ago when I was in high school I made a portable battery amp using two of them. I used a small input audio transformer as a phase splitter, with a dual op-amp chip as a pre-amp for each LM386 chip and bridged the outputs of each LM386 chip, 100uF coupling capacitor, across 8Ohms. This drove them a little hot, so I put a small IC heatsink on them. This was probably the simplest design that I have made that worked so well. It put out 5-8 Watts cleanly.

Sometimes simple is just better. :D
 
cunningham said:
I'm not too familiar with TDA7266, but LM386 is perfect for your application. It is a DIP 8-pin package.

I remember long ago when I was in high school I made a portable battery amp using two of them. I used a small input audio transformer as a phase splitter, with a dual op-amp chip as a pre-amp for each LM386 chip and bridged the outputs of each LM386 chip, 100uF coupling capacitor, across 8Ohms. This drove them a little hot, so I put a small IC heatsink on them. This was probably the simplest design that I have made that worked so well. It put out 5-8 Watts cleanly.

Sometimes simple is just better. :D

the LM386 is a bad-sounding chip -- even ham radio ops complain about it (although widely used.)
 
Just another thought...

If you used descrete componants, you could use very small, even surface mount devices, high freq., high gain for the diff. and VAS stages. Bias these stages each to use around 200-300 uA each, and use a current sourced diode biased class AB circuit for the power stage. A current sourced diode biased intermeadiate stage might be needed, but this will still keep the overall idle current low. This would not drain the batteries.
A couple of TO-126 case style devices would be plenty big enough for output probably without any heat sinking. Just do everything on a smaller scale. With surface mount componants you can cram it all onto a small circuit board.

It takes more componants, but choose cheap componants. Just because it costs less dosen't mean it is not as good. Cost has more to do with availability.

You can get more bang for your buck and better sound. Birds may be able to hear a distorted call.

Chris
 
Hi Cunningham,

That IS a very tempting idea. I'm am confinced that the quality of a discrete design can easy be supurior to such a TDA7266 IC. I can proberbly get more power into the load too, using a suiteble topology. You also have a good point for the idle current. This IC uses alot of idle current, while, if I would design for it, I could get it into the 1-5mA range..

Maybe, maybe.. but first i'll see how this IC works for me...


Regards,
Thijs
 
I thought that this may be interesting to use descrete componants for a portable small amp, with good dynamic range.

I took it upon myself to do some calculations, please check them.


This circuit would require two 6V lantern batteries, and could be constructed inside a small speaker box.
 

Attachments

  • small-amp.jpg
    small-amp.jpg
    91.1 KB · Views: 237
Hi Cunningham,

Thx for your effeort! I will check it out. I probberbly need to modify a bit to make it run of a single 9V supply. I would like to test it in 8 Ohm bridged.. not many 4Ohm small speakers around :-( .. Could there be a way to bootstrap the VA-stage in both directions? getting another 0.6 Volt PP from that?



Regards,
Thijs
 
Guitar Amplifier

Hey guys!

I am new to diyaudio forum. Actually i am also new to guitar. I have an acoustic guitar with pickups installed over the sound hole and i dont have enough money to buy an amp. so could you geniuses please help me in building an amp with an output of about 5-10W. By the way I line in INDIA.

thank you,
MANANZS
 
Hey guys!

I am new to diyaudio forum. Actually i am also new to guitar. I have an acoustic guitar with pickups installed over the sound hole and i dont have enough money to buy an amp. so could you geniuses please help me in building an amp with an output of about 5-10W. By the way I line in INDIA.

thank you,
MANANZS


I hav made a very nice sounding amp from Tda 2030 ic works on 12v amd gives out 14W........i purchased it for Rs 30 frm delhi....
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.