Help/Advise needed on Electric Designers in Bangalore

[turgid]

Hi All,

Very new to HFV. Been into audio for the past 4 years. Joined this site sometime that I don't remember but Gurubhai refreshed memory yesterday.

As for the matter in hand, please could you list details of any circuit designers in Bangalore that any of you have availed help from.

And the advise part, could one remove transformers from AC adapters that step down voltage and reverse it to amplify speaker out?

Thanks,
A~

 

[turgid]

Thanks for the prompt response(s).

 

[diesel engine]

Hi All,

Very new to HFV. Been into audio for the past 4 years. Joined this site sometime that I don't remember but Gurubhai refreshed memory yesterday.

As for the matter in hand, please could you list details of any circuit designers in Bangalore that any of you have availed help from.

And the advise part, could one remove transformers from AC adapters that step down voltage and reverse it to amplify speaker out?

Thanks,
A~

what is your purpose of using the trafo like that? anyway, you cant amplify signals. but to carry amp output to long distances, that is viable. but you have to design the trafo accordingly. but fidelity will be compromised

 

[turgid]

what is your purpose of using the trafo like that? anyway, you cant amplify signals. but to carry amp output to long distances, that is viable. but you have to design the trafo accordingly. but fidelity will be compromised

Many Thanks for the reply.
Hopefully I am mostly getting one custom made/wound as per requirements.
I have no problem with the fidelity at this point of time.

 

[Fantastic]

You can connect a transformer the way you want. However you have to remember that the 'load' you connect at the end will appear at the amp in proportion to the square of the turns ratio of the transformer.
Eg: a 240/120 v transformer has a turns ratio of 1:2 . So if you connect 16 ohms to the output terminal of the transformer, the load at the amp will appear to be 16/2^2 = 4 ohms.
If it is a 240 /12 v transformer, the turns ratio is 1: 20. If you connect the same 16 ohms to the transformer , it will appear as 16/20^2 = 0.04 ohms at the amp ! That will be almost like shorting the output of the amp. Minimum load has to be 4*20^2 = 1,600 ohms to look like 4 ohms at the amp.

Besides this you will have bandwidth problems if the windings are not made accordingly. Audio transformers are not wound like regular power transformers. And then there are issues with what core material you use ........etc....

 

[turgid]

Thanks a ton for the info, its actually Fantastic

 

[diesel engine]

Many Thanks for the reply.
Hopefully I am mostly getting one custom made/wound as per requirements.
I have no problem with the fidelity at this point of time.

You dont have to make it custom built, I think. It is a standard audio equipment. Ever seen the 100V tapping on the back of PA amps?
Try any Ahuja store.

 

[turgid]

yes 4ohm, 100V line ones .. yeah? OK I will try the store. I just wanted a considerable step up from the output of the amp/receiver. Probably 1:80 or 1:100.

Talking about that, how much voltage will an amp/receiver put out to feed such a transformer given the amplifier ratings are 65Wpc at 8 Ohms?

I just went across with calculations as per some basic formulae:

65 W = V*I

Per Ohm's Law:

I= V/8 ( ? )

so

65 = (V^2)/8

or V = 22.8 ? I find that hard to believe.

Regards,
~A

 

[diesel engine]

yes 4ohm, 100V line ones .. yeah? OK I will try the store. I just wanted a considerable step up from the output of the amp/receiver. Probably 1:80 or 1:100.

Talking about that, how much voltage will an amp/receiver put out to feed such a transformer given the amplifier ratings are 65Wpc at 8 Ohms?

I just went across with calculations as per some basic formulae:

65 W = V*I

Per Ohm's Law:

I= V/8 ( ? )

so

65 = (V^2)/8

or V = 22.8 ? I find that hard to believe.

Regards,
~A

Do it this way:
Power P= Vsquare/R
ie, V=sqareroot of P*R

=square root of 65*8= root 520 = 22.8V
and the circuit carries a current of 23/8= aprx. 3A.
design a trafo to this spec and you are done.

 

[turgid]

I ordered a 3V to 240V trafo...I wanted considerable step up ~ 73 with losses.

Eitherway, I put the amp out as per above calculations to this 3V in and PROBLEM??? :O

they said thed trafo do not have a ground/neutral to ground it with other parts of my circuit....

 

[haizishangxu]

That will be almost like shorting the output of the amp. Minimum load has to be 4*20^2 = 1,600 ohms to look like 4 ohms at the amp.

 

[turgid]

That will be almost like shorting the output of the amp. Minimum load has to be 4*20^2 = 1,600 ohms to look like 4 ohms at the amp.

I will connect a resistor in series to the amp out, hence some 'load'. Trust this will be sort the issue ?

noob moi!

 

[turgid]

I just opened 2 defunct step down adapters rated for same values - one made in India and other in China.

There is definitely a whole lot of difference in quality. (at least to the eye)

 

[diesel engine]

what is this?

 

[diesel engine]

That will be almost like shorting the output of the amp. Minimum load has to be 4*20^2 = 1,600 ohms to look like 4 ohms at the amp.

what is this? the load offered by an inductor is the flux it produces. not the DC resistance

 

[diesel engine]

I just opened 2 defunct step down adapters rated for same values - one made in India and other in China.

There is definitely a whole lot of difference in quality. (at least to the eye)

buddy, the one at top is no trafo. its an SMPS

 

[linuxguru]

buddy, the one at top is no trafo. its an SMPS

Correct - actually, it seems to be an electronic ballast for a tubelight fitting or similar.

 

[diesel engine]

dear turgid, what exactly is in your mind? if you want to transmit speaker out of an amp to a long distance,say 200m, Ahuja line trafo is enough. connect it reverse at the source.

 

[turgid]

You can connect a transformer the way you want. However you have to remember that the 'load' you connect at the end will appear at the amp in proportion to the square of the turns ratio of the transformer.
Eg: a 240/120 v transformer has a turns ratio of 1:2 . So if you connect 16 ohms to the output terminal of the transformer, the load at the amp will appear to be 16/2^2 = 4 ohms.
If it is a 240 /12 v transformer, the turns ratio is 1: 20. If you connect the same 16 ohms to the transformer , it will appear as 16/20^2 = 0.04 ohms at the amp ! That will be almost like shorting the output of the amp. Minimum load has to be 4*20^2 = 1,600 ohms to look like 4 ohms at the amp.

Besides this you will have bandwidth problems if the windings are not made accordingly. Audio transformers are not wound like regular power transformers. And then there are issues with what core material you use ........etc....

Mr Fantastic,

I dont understand! Doesn't a step down trafo of 240 to 120 V have 2:1 turns ratio?
and a 240 to 12 have 20:1 ?

Is n't Vp/Vs=Np/Ns?

 

[diesel engine]

Mr Fantastic,

I dont understand! Doesn't a step down trafo of 240 to 120 V have 2:1 turns ratio?
and a 240 to 12 have 20:1 ?

Is n't Vp/Vs=Np/Ns?

Dear fantastic, isnt' it a bit confusing, buddy?