DIY: Pass F5 turbo v2 initiated

[baswamin]

Om,

Are we planning on using 2 transformers, each 24-0V, 300VA and generate +32 - 0 - -32V supply instead of going for center tapped transformer? So essentially, we create a center tapped transformer from 2 individual transformers, is this correct?

Secondly, dont we need soft start if we use NTC's?

Thanks

Here we are initiating with stereo configuration of 2 mono blocks.
PCB boards:
2x mono amp,
2x PS filters, 1 per mono block
1 rectifier for 2x2 secondaries, will cater for 2 filter board of 2 mono
Parts:
2x mono amp complete /w Fairchild Matched MOSFets, Toshiba JFETs, MUR diodes and element 14 parts.
1x PS rectifier MUR diodes only, other parts not included & can be locally - metalized box type polyester caps 5mm lead spacing
[2x PS filters - nothing all parts can be locally procured - power caps, resistors and polyester caps.]


Remaining items (not included here)-
2 X Transformers [ 24-0,24-0,300VA]
2 X heatsinks
chassis for dual mono/ stereo
Optional soft start if not using provided 10 ohm NTC
Optional speaker protection if you feel uncomfortable with DC Amp
Rocker switch, 20mm fuse holder, IEC socket, 2xRCA, 2xbinding Post pairs, indicator LEDs, internal wire etc
2 X 35A rectifiers for connecting PGND of two filter grounds and earth ground together in lifted ground configuration

 

[kroyin]

Both the transformers have to be center tapped 24-0-24 (or) you can use a single 600VA 24-0-24.

Om...one needs to procure thermal pads for mounting the MOSFETS (to the heatsink) and MUR Diodes (whose cases are electrically conductive) to their heatsink (not sure whether they can be mounted to the main heatsink).

The local Mica pads are bad, they are flaky, have air bubbles in them. In short you cannot use them.

Also this might be a far out does anyone have a source for plastic screws

 

[omishra]

Om,
Are we planning on using 2 transformers, each 24-0V, 300VA and generate +32 - 0 - -32V supply instead of going for center tapped transformer? So essentially, we create a center tapped transformer from 2 individual transformers, is this correct?

In case of center tap, that center tap is direct ground to amp board.
There are no pros or cons but I got better results in former.
The way I designed rectifier and PCB that you can use it in both the configurations.
In 24-0, 24-0 case you get all wire to rectifier and output of rectifier to filter.
In 24-0-24 case you get all 24V wires to rectifier and 0 directly to filter.
From Filter onwards wire count and polarity are same in both the cases.

Advantage? if you buy 2X(24,0) secondaries you can easily make them in series and convert 24-0-24 but reverse is not true. Both of the above cases can be tried with 2X(24-0).

I am planning to use 2 transformer with 2 secondaries each. From that I will derive floating ground on the filter board.

Secondly, dont we need soft start if we use NTC's?

Yes, But apart from softstart some softstart boards have thermal cutoff. Like this example

Both the transformers have to be center tapped 24-0-24 (or) you can use a single 600VA 24-0-24.

Using single transformer is also possible. I thought let's make them separate, even grounds are also separated. That's why earth ground connection is planned through 35A rectifier block + 10? NTC.

Om...one needs to procure thermal pads for mounting the MOSFETS (to the heatsink) and MUR Diodes (whose cases are electrically conductive) to their heatsink (not sure whether they can be mounted to the main heatsink).

The local Mica pads are bad, they are flaky, have air bubbles in them. In short you cannot use them.

Also this might be a far out does anyone have a source for plastic screws

I thought about KERAFOL/KARATHERM. but they are not available locally. Another replacement for Mica is Silpad which are locally available at industrial dealer. No paste required into that. IMO these will be required for MOSFETs also.

Also this might be a far out does anyone have a source for plastic screws

Why you want this? I have seen nylon screws in M3 size but I feel they would change properties at 50-55 degC constant temperature.

 

[kroyin]

Does Torotrans sell with dual secondaries (24,0/24,0)?

I did say far out -)) when i referred to plastic screws.

 

[omishra]

Does Torotrans sell with dual secondaries (24,0/24,0)?

Yes, I got below from them for Rs 1500/- each:

Primary 230VAC
Secondary 24-0,24-0 VAC, 300VA total
Lead length 12"
Magnetic shielded screen/ring

Quantity: 2 ( two)

 

[sachu888]

Hi all,
Please confirm your participation.I have ordered PCbs today.I will need min 50% amount in 2-3 days.I am listing confirmed members for GB here.Please update here if anyone has doubts.

PCB Set (2XAmp + 2X Filter + 1 Rectifier): (c/o Sachin) Approx cost Rs 3000/ea
1.CaptRajesh
2.Omishra
3.Cmsajith,(2 sets)
4.Santosh
5.Sachin
6.Kroy
7.Bhaskar
8.Baswamin
9.Anilva
10.Sann
11.Gvanu (2 sets)
12.George

Matched Fairchild MOSFETs 2X (2p,2n)+MUR diodes(24) (c/o Captrajesh)
This will be bought from DIYAudio US member. apprx cost Rs 4500/ea, refer kroyin's post for cost.

1.CaptRajesh
2.Omishra
3.Cmsajith,(2 sets?)
4.Sachin
5.Bhaskar
6.Baswamin
7.Anilva
8.Sann
9.Santhosh,
10.Gvanu (2 sets)
11.George

Amp board: element 14 + matched Toshiba JFETs for stereo
Approx cost (3000 + 1200)/ea with 4XNTC (4.7K?) + 4Xpresets (5K?) will be locally procured.

1.CaptRajesh
2.Omishra
3.Cmsajith,(2 sets?)
4.Sachin
5.Bhaskar
6.Baswamin
7.Anilva
8.Sann
9.Santhosh,
10.Gvanu (2 sets)
11.George

Remaining PS caps and transformer will be as per your own taste or locally available Nippon Chemicon.

Regards,
Sachin

 

[kroyin]

Sachin,

I'll transfer 1500 to you for the PCB set.

 

[anilva]

Sachin,

I will transfer 1500 today to you.

Cheers.

 

[Audiodoc]

Torotrans will sell you any combination. Just tell them the input voltage 0-230 and secondary voltages and VA value.

I have purchased more than 15 from them and they work fine as long as your circuit is OK. I think only one 0-12V 1 Ampere went kaput possibly because of a circuit fault.

 

[GeorgeO]

Will transfer today and PM you.

 

[baswamin]

Sachin,

Will transfer the amount today.

 

[sachu888]

HI all,
I have received 50% advance against F5 PCBs from following members.

1.George
2.Omishra
3.Bswamin
4.Anilva
5.Kroyin
6.Sann


Regards,
Sachin

 

[sann]

Hi Sachin,
I have transferred 1.5K to your a/c.
-Sann

 

[sachu888]

Hi Sachin,
I have transferred 1.5K to your a/c.
-Sann

Thanks Sann,
I have updated the list

Regards,
Sachin

 

[cmsajith]

Transferred 3K, please confirm

 

[santhosh]

Hi Sachin,
Transferred 3k, should hit your account tomorrow morning. Thanks.

 

[sachu888]

Updated list for F5 PCBs

Received 50% amount for PCBs from following members

1.George
2.Omishra
3.Bswamin
4.Anilva
5.Kroyin
6.Sann
7.Cmsajith
8.Santhosh(full PCB amount)

Regards,
Sachin

 

[sachu888]

Updated list for F5 PCBs

Received 50% amount for PCBs from following members

1.George
2.Omishra
3.Bswamin
4.Anilva
5.Kroyin
6.Sann
7.Cmsajith
8.Santhosh(full PCB amount)
9.Capt.Rajesh(full PCB amount)

Regards,
Sachin

 

[captrajesh]

Matched Fairchild MOSFETs 2X (2p,2n)+MUR diodes(24) (c/o Captrajesh - Sachin told about his conversation)
This will be bought from DIYAudio US member. apprx cost Rs 4500/ea, refer kroyin's post for cost.

Omishraji, oopsy you have made it official!!

We were talking on phone the other day when he was mentioning about the problem of importing so much stuff when I offered to utilise my consultant who keeps importing electronic stuff from abroad and even has an IE code. But I'm not sure if he would be able to import from individual/ He generally imports from reputed suppliers like parts express, Element 14 etc.

 

[sachu888]

One of my friend has IE licence.I will talk to him today.

Regards,
Sachin