Hello friends,
I am in search of a amplifier circuit for construction which can:-
1.Drive 16 ohm load
2.work from 12 volt or max 2 X 12 = 24 volt car batteries directly.
3.can deliver power in the range of 10-200 watt.
4.No smps power supply for supply voltage boost.
5.For speech purpose mainly.(no need of high fideality)
This requirement came from necessity as in my village there is frequent power cuts and though i have some big amps but those all work on mains only.
In my country these type of amps like link given below are available for the same purpose commercially but i am interested in diy ones.
Kindly help me.
regards
sudhir.
http://www.diyaudio.com/forums/solid-state/188940-ahuja-amplifier.html
Ahuja Sound Solutions
I am in search of a amplifier circuit for construction which can:-
1.Drive 16 ohm load
2.work from 12 volt or max 2 X 12 = 24 volt car batteries directly.
3.can deliver power in the range of 10-200 watt.
4.No smps power supply for supply voltage boost.
5.For speech purpose mainly.(no need of high fideality)
This requirement came from necessity as in my village there is frequent power cuts and though i have some big amps but those all work on mains only.
In my country these type of amps like link given below are available for the same purpose commercially but i am interested in diy ones.
Kindly help me.
regards
sudhir.
http://www.diyaudio.com/forums/solid-state/188940-ahuja-amplifier.html
Ahuja Sound Solutions
A transformer coupled amp with 24 volt supply like the ones you are wanting will only put out 7-8 watts max into 16 ohms. The correct transformers most likely will be difficult to find unless you can make your own. A better solution would be to use amplifier IC's designed for use in car audio and use lower impedance speakers.
Do the arithmetic.
24Vdc can allow an absolute maximum output of ~8Vac, equivalent to 11.3Vpk = 22.6Vpp.
Into a speaker load expect 1 to 2 volts less than that.
i.e. 7Vac (19.8Vpp) from 24Vdc gives a maximum power into 16ohms of V²/Load = 7*7/16 = 1.75W
That's it. No more. Built badly it will be less !
24Vdc can allow an absolute maximum output of ~8Vac, equivalent to 11.3Vpk = 22.6Vpp.
Into a speaker load expect 1 to 2 volts less than that.
i.e. 7Vac (19.8Vpp) from 24Vdc gives a maximum power into 16ohms of V²/Load = 7*7/16 = 1.75W
That's it. No more. Built badly it will be less !
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If you decide it worth while you could build two amplifiers designed to drive 8ohms.
Then you have the option to bridge the outputs to get more power into your 16ohms speaker.
an 8ohms amplifier may be able to push 6.5Vac into 8ohms.
Calculate the maximum 8ohms power.
A bridged amplifier can deliver a maximum power that is double the single into double the load impedance.
Then you have the option to bridge the outputs to get more power into your 16ohms speaker.
an 8ohms amplifier may be able to push 6.5Vac into 8ohms.
Calculate the maximum 8ohms power.
A bridged amplifier can deliver a maximum power that is double the single into double the load impedance.
I have commercially made 40 and60W/4 ohms with transformer output, similar to what you post.
And believe me, in the long run it was much better, simpler and cheaper to make a power inverter and be free to use any circuit I like.
So I suggest you do that.
It´s always easier than trying to find the proper transformer.
I wound my own, and yet ...
That said, obviously that must be a common problem in India, that´s why Ahuja is such an important and successful company, specializing on them.
I´ve helped Techs repair them, in different Forums, and they are excellent but real complex.
And believe me, in the long run it was much better, simpler and cheaper to make a power inverter and be free to use any circuit I like.
So I suggest you do that.
It´s always easier than trying to find the proper transformer.
I wound my own, and yet ...
That said, obviously that must be a common problem in India, that´s why Ahuja is such an important and successful company, specializing on them.
I´ve helped Techs repair them, in different Forums, and they are excellent but real complex.
Thanks for reply, I am trying to get transformer from some old amp.16 ohms because i want to drive the horn unit which usually come in this impedance only.
regards
sudhir.
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Thanks for reply sir. I have done the arithmetic thats why I want to make a transformer coupled amplifier.
regards
sudhir
Thanks for reply sir. I am very happy to know that a designer is on other side.I have commercially made 40 and60W/4 ohms with transformer output, similar to what you post.
And believe me, in the long run it was much better, simpler and cheaper to make a power inverter and be free to use any circuit I like.
So I suggest you do that.
It´s always easier than trying to find the proper transformer.
I wound my own, and yet ...
That said, obviously that must be a common problem in India, that´s why Ahuja is such an important and successful company, specializing on them.
I´ve helped Techs repair them, in different Forums, and they are excellent but real complex.
But practically i have seen very few failure in these type of amps (say ahuja type) here in India.Adding a inverter to amp itself more complex process. I am ready to wound a trafo if proper info is provided.
My problem is that i have to drive 16 ohm load strictly.Hope you will suggest some solution.
thanks
sudhir.
What if I use a amplifier designed for working on 12-24 vdc on 4-8 ohm load and couple its output to a 16 ohm load through a transformer which work like a impedance matching trafo. (tranfo have primary : seconday :: 1:2 or 3)
regards
sudhir.
That will be last option sir, even then what about driving a 16 ohm load i.e a horn driver like below.
thanks .
sudhir.
Attachments
The transformer doesn't have to be made specifically for this. Think about what you can get cheap. If you don't need high fidelity, standard power transformers work just fine for audio. A fairly large 24 to 36 volt center tapped to 120V EI core trafo, driven in push pull with some high power cheapo NPN transistors will give a decent amount of output off a 12 volt battery.
Your whole project hinges on what transformer you can get your hands on. If you have access to old salvage parts, look for old Motorola car 8-track players with germanium output transistors and input/output transformers. I built a decent booster from one of these in 1974. Back then the new car audio products used single ended transformerless outputs and never produced more than a couple of watts; this booster provided plenty of power to drive 8 ohm speakers. Later on I used it to boost the output of a cheap home stereo and it worked great for this application too. Hi fi it was not; but it provided loud and clear sound and music sounded fine. I never measured the output power but it wasn't 100 watts, I assure you.
Another option to explore is using a 70 volt line transformer with the secondary used as the primary. You'd have to find the right one (might find a decent salvage unit) and design a circuit to drive it. Maybe consider parallel transformer configurations to reduce winding current. 100 watts would be a stretch.
Any modern mobile audio amplifier designed for vehicle hi fi systems will drive your 16 ohm speakers fine. It will provide greatly reduced power output though; a 100 watt amplifier will probably only deliver 25 watts. Maybe if you could find a true 300 watt amplifier you'd be in the ballpark. A bonus is that using the amplifier for 16 ohm speakers will greatly reduce power dissipation and heat.
Do you really need 100 watts?
I had imagined so.
Then forget
, typical PA reentrant horns can´t safely stand more than 25W ; 40W tops.
But they are VERY LOUD with that power input.
A simple bridged amp fed from 2 x 12V batteries in series will put out some 20/21V peak *tops* , some 14V RMS, which into 16 ohms means 12W RMS per horn.
So now you see you need that SMPS.
If that's all you're driving, then any car audio amplifier in the neighborhood of 100 watts/4 ohms powered by a car battery will be sufficient. This will provide around 25 watts of clean power for your horn, which I suspect is a lot more power than you think. Can you get a used one cheap or free?
The Ahuja '200 watt' amplifiers would struggle to put out 30 clean watts. Factor that into your calculations. They are basically 'Line' amplifiers, with high voltage 100/70V outputs that cannot be directly connected to a speaker, and are meant to run long cables.
The amps also have a 8 and 4 ohm tap, that can do about 25 watts of clean power from a single 12V battery.
The transformer at the speaker is the reason a 16 ohm load is even possible from a battery.
200 watts is extreme optimism on the part of the manufacturer/marketer.
The amps also have a 8 and 4 ohm tap, that can do about 25 watts of clean power from a single 12V battery.
The transformer at the speaker is the reason a 16 ohm load is even possible from a battery.
200 watts is extreme optimism on the part of the manufacturer/marketer.
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