[INDIA] Any DIYer made a Gainclone in India. willing to help? - Page 2 - diyAudio
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Old 28th April 2004, 06:29 PM   #11
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HI roadkill

Can you if possible post detailed parts list. I will be using LM3875 chips. I am not too keen on the kit route. Would like to try doing it myself. It is quite interesting roaming in the market trying to collect parts. ;-)

What caps do you suggest?

TIA

Sudeep
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Old 29th April 2004, 12:29 PM   #12
sunil is offline sunil  India
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Guys, you are in a different league altogether. I used paypal. The kit comes in parts & customs is not usually bothered about this. They have bigger fish to catch.

Abidr,

Point taken. The kit route does not justify the DIY spirit. However, I find it difficult to learn electronics. I prefer to go the kit route. I am more inclined towards DIY speakers which I have made my own & have spent a lot of time doing . 3-way active.

Roadkill,

Yes, I did a quick visit of the market here in Blr & I know the parts put together cost about 200/- Did you design your own pcb ? Why don't we do a high-power bridge/parallel/b-p ?
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Old 29th April 2004, 02:02 PM   #13
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OK:
now heres the catch if you want to do it yourself i could email u schematics and PCB designs of a 5.1 Amp using LM3875 which you could easily modify to a stereo application, or a 2.1 using TDA1514 with two single chips and two bridged. All you ll have to do is make a PCB or better get it made by some friend.
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Old 29th April 2004, 03:00 PM   #14
sunil is offline sunil  India
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Yummy, the 5.1 sounds really good. However, with Brianís kit itíll be the third amp I have. Why not work on the high power version for a sub ? Some serious power ?
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Old 29th April 2004, 05:45 PM   #15
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Hi, I'd be happy to design a PCB based on National's BPA200 or BPA100, but these are for LM3886, not LM3875. I believe they are the same except for one pin which on the 3886 is V+ and on the 3875 is an NC. And yes, I made my own PCB, which I've posted here.

Then again, Abid has already said he's willing to release his designs. You can print the foil patterns onto paper with a laser printer and give it in at Om Electronics, SP road for a single-sided PCB. It's cheaper to make a PCB for one amp, and ask him for multiple copies of the board.

Detailed parts list:
it's straight out of the 3886 datasheet. I've used metal film resistors (1% tolerance. Gain setting resistors were sorted for matching value), film capacitors for HF bypass, ceramics for RF rejection, Samsung electrolytics (470u/50V) for local (on-board bypass, not to be confused with the bypass caps on the PSU). I also used Relimate connectors for signal and Phoenix-type moving cage wire terminations for speaker connection and power input. The PCB is tiny, it's just 1.7" by 1.7". As I've already mentioned, I'm not a believer in capacitor sound. At least, not for the filter caps. Just to be sure, I bought some Elna For Audio caps (10000 uF/71V) to use in an amp (gainclone) I built for a friend... no difference.

Sunil,
I know most ppl believe the chip amps dont sound good. I for one think they sound great... perhaps maybe even a little too great to waste on a sub. For a sub, you can get away with using a regular class B or AB amp with relatively cheap output transistors, biased at a point which will give a bit of distortion but keeping them cool. That's what I've done, anyway: a dual P3A bridged. I use some transistors labelled with "2SA1302" etc, but I'm pretty sure they're fake. So far, no fireworks, no problems. Been using this amp every day for the past 3 months.

One thing about using Brian's PCBs: my oh my they look good! Compared to the (relatively) crappy looking PCBs we get here, they're awesome.
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Old 30th April 2004, 01:58 AM   #16
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Default Elna 10000u/71V

Hi Roadkill,
Where ( shop name) did you get those Elna 10000u/71V caps ? How much did they cost ?
I can only find 10000u/56V .
Thanks.
Ashok.
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Old 30th April 2004, 10:54 AM   #17
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I bought those from Vishal Electronics. He had 4700 uF/50V once, but not any more. I believe Cee Pee Electronics stocks them too. Don't remember the exact cost, I think it was ~70 bucks each.
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Old 30th April 2004, 11:44 AM   #18
palesha is offline palesha  India
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Diy means doing everything ourselves & knowing/learning the art of electronics. Calcutta, Mumbai, Delhi, Banglore & Chennai hv excellent component shops. Beside IC's, u can get very wide range of condensors now. Initially not knowing the source is a problem but better to look for shops in ur own city. Knowing this takes lot of time but it is a long term proposal for serious DIY. If u still need help, lot of friends r here to help.
Mahendra Palesha
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Old 30th April 2004, 02:48 PM   #19
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Default Thanks.

Thanks Roadkill,
I will check that out.
I can't find any 10kuF 71 V caps in Chennai. There are lots of 50V and 100V caps. Even 75V and 63V are not easy to find. The few 63 V caps I found are made by strange companies. I suspect that they may be Chinese. The ( blue) 100V computer grade ones look very dusty. I wonder if they are pretty old and taken off the shelves from other countries. It says Sprague on them.
Cheers,
Ashok.
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Old 30th April 2004, 05:07 PM   #20
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Why the fixation on 71 V anyway? If 50V is too low, use a 100V cap. They're only a little bigger/expensive.

BTW, Amar Radio has Alcon make computer-type capacitors, both with screw terminals and with solderable lugs. I bought the lug kind for Rs. 120 each (10000uF, 63V). These are brand new, and I can vouch for Alcon caps being good: I have a 17 year old Alcon cap whose value is within spec.
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