Transformer Power Rating

[Staigen1]

Hi

The resistor shall also be connected to the coil and have the value of 1 ohm!
Read the description, even if it is not very clear, the resistor and the coil is parallelled


//Staigen

 

[faizanbrohi]

I Know About the 1ohm resistor , i have not fully assembled the project , i am just asking if the inductor is wound right.

 

[Staigen1]

I have seen a lot of these resistor/inductor combination, but they have all been wounded over the resistor and connected at the end of the resistor, the resistor itself usally is between 1 ohm and 10 ohm. The resistor lowers the Q of the coil!
The coils you have done is just fine, maybee you should spread the windings a little.

//Staigen

 

[audioguru2]

The resistor shall also be connected to the coil and have the value of 1 ohm!
Read the description, even if it is not very clear, the resistor and the coil is parallelled

I disagree. R14 is 1 ohm and is already in parallel with the coil. The pcb shows a diagonal holes layout for the coil to be connected, not for the resistor it is wound on.

Maybe the parts list value for R14 is wrong. All power amplifier circuits I have seen use a 10 ohm resistor in parallel with the coil.

There are many good audio power amp circuits on the web. Why struggle with this one's odd darlington transistors and errors on its pcb layout, schematic and in its parts list?
View attachment 38362

 

[Staigen1]

Hi

I disagree. R14 is 1 ohm and is already in parallel with the coil

Oops, i made a mistake! Yes Audioguru, the coil is not wound around R14, but connected in parallell with it! Then your coils are just right as they are, faizanbrohi!

Maybe the parts list value for R14 is wrong. All power amplifier circuits I have seen use a 10 ohm resistor in parallel with the coil.

I agree with you here too, but i have seen 4.7 and 6.8 ohms also, but usally it is 10 ohms.

Why struggle with this one's odd darlington transistors and errors on its pcb layout, schematic and in its parts list?

I dont disagree here either, but it is up to each one wich project to build ;D

//Staigen

 

[faizanbrohi]

The resistor is surely 1W but it is just a little longer thats all , does the length of it effects anything , because you just need the dia of a 1W resistor of any value.

 

[audioguru2]

Your resistor doesn't look like it is the same as a modern one. Use a modern one.

 

[faizanbrohi]

Audioguru i have compared the 1W resistor diameter with the modern one also , the diameter is actually the same ... but the difference is its length... and ofcourse we
are only interested in the diameter...

 

[audioguru2]

Many other amplifiers I've seen have nothing inside their coil at the output. Since your 1W resistor is the correct diameter then it will be fine.

 

[Staigen1]

Hi

I dont think you need the resistor, the coil can be airwound, its so small and have enough gauge to support itself!

//Staigen

 

[Staigen1]

Hehe Audoiguru, replying at the same time


//Staigen

 

[audioguru2]

Hehe Audoiguru, replying at the same time

I beat you by less than 3 minutes!
Great minds think alike. ;D

 

[Staigen1]

Hi Audioguru

What do you think of making the coil airwound?


//Staigen

 

[audioguru2]

Hi Audioguru
What do you think of making the coil airwound?

Yes, but its wire size is small so it might get crushed.
I would use 1mm wire for an airwound coil.

 

[Staigen1]

Hi

I would use 1mm wire for an airwound coil.

I think 0.8 mm will be just fine, its only 10 turns

//Staigen

 

[faizanbrohi]

Hello Everyone , i have a query . The BDW84D BDW83D darlington pairs were really hard to find but luckily i found them. i am wondering if we can use substitute parts for the BDW84D and BDW83D , which are available like BDW84A and BDW83A is really easy to find and even BDW84D is easy to find . So my question is that is there a substitute for BDW84D and BDW83D.
one more thing i am remaking the inductr and this time winding it on another resistor of 1W with smaller length , i will send some pictures soon of the inductor and the darlington transistors i found also...

 

[ante1]

The last letter is the voltage!

 

[Mickey1]

The last letter is the voltage!

I know that the last letter is the voltage, but I wonder what would happen if I put my BDW83 & 84 "C" version? I'm about to finish the project soon, and I plan to put these transistors...what do you propose?
Also, do you think that it will be enough if I put transformer which has 2x23V in the secondary and use it with the electrolyth capacitors 3x4700mF/63V = 14100mF for (+) and 14100mF for (-) voltage?

Thanks.

 

[Mickey1]

P.S. did anyone of you guys actually finished the amp? iS pcb CORRECT OR NOT? How does it work, huh?

 

[Staigen1]

Hi there

I checked the voltage of the BDW 83/84 transistors and the C stands for 100V collector voltage and the D stands for 120V collector voltage!
This means that either the C or the D verson can be used in this cirquit!

Mickey, the tranny shall be a 2X28V/8A type, not a 2X23 Volt type! 3X4700uF/63V lytics will be just fine!

I have not built this amp, and will never do, there are better amps!


//Staigen