[INDIA] Any DIYer made a Gainclone in India. willing to help? - diyAudio
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Old 24th April 2004, 04:21 PM   #1
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Default [INDIA] Any DIYer made a Gainclone in India. willing to help?

Hi
Calling DIYers in India. Anayone made a Gainclone and willing to help with pcb, power supply ideas etc..

I am a complete newbie but would like to make a gainclone.

All help appreciated.
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Old 24th April 2004, 06:38 PM   #2
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smarcher,
The idea I had of using a [INDIA] tag on the subject line was for something specific to India, ie, where to get components, where to look for raw materials. It was not intended to propogate this very typical mentality all of us Indians seem to share: groupism. I'm sure lots of people from other countries are more than happy to help you out with ideas and advice, not just the few of the members from Bharat So unless you have some info/query which is specific to India, please don't use the [INDIA] tag... if anything, you'll get fewer replies from others.

That aside, I believe Tarun has made a gainclone based on the LM3875. I've made a pair based on the LM3886. If memory serves me right, Ashok and a few others have made gainclones based on the Philips ICs (TDA series, I forget the part no.). What kind of specific help are you looking for?
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Old 25th April 2004, 05:27 AM   #3
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Hmm
You have answered your own criticism of my using the India tag. To make a gainclone I would not need to post anything on this forum since there is so much info available on the Net. Especially with BrianGt's excellent user manual.

I used the INDIA tag exactly for the purpose of knowing what parts indians were using so as to get an idea of what is available in the local market.

Specifially, I wanted to know what capacitors (brand name) and power supply are used.

Anyways, lets not quibble since this is also a so called Indian trait.

Thanks
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Old 25th April 2004, 10:31 AM   #4
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Ok, gotcha. It just wasn't that obvious from your first post what kind of info you were looking for.

Capacitors: I've used Samsung 4700uF/50V x2 (per rail) in a C-R-C form. Each cap is bypassed with a 0.1uF ceramic. The PSU is built on a PCB. You could also look for screw-terminal capacitors and build the PSU without a PCB, although this would be more expensive. I've also put 0.1uF film capacitors across the diodes in the bridge rectifier to reduce switching noise. Others have commented that this is not of much use unless there are small resistors in series with the diodes. This is not an option for me since I have used encapsulated bridges. Attached is a pic of my PSU board. From left to right, you can see the input connectors (green), bridges (black), film caps (yellow), filter caps (blue and gold), resistor (red), output connector (green), fuse holder (black) and ground connector (green). Excuse the lousy quality my webcam puts out... BTW, all these components are locally available, and have not been ordered thru any mail-order firm, etc.

Transformers: If you want to use toroidal core trafos (maybe to save space), one good source is Miracle Electronics (www.toroidal.com), they are based in B'lore and will courier transformers to wherever. Their website has an extensive catalogue, and you can email them for a quote. I've used an E-I core for both the amps I've built so far, but one which is now under construction will make use of a 25-0-25 225VA toroid core I bought from Miracle. One problem with Miracle is they are a bit expensive (I paid ~Rs. 1400 for mine, incl shipping + tax). Perhaps the Calcutta local electronics market will have cheaper transformers. For your first amp, you may want to settle for something a bit less expensive.
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Old 27th April 2004, 04:07 PM   #5
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Hi roadkill

Thanks for the detailed reply. I am a complete newbie but am really interested in this amp. I was trying to follow BrianGt's schematic. I set out to find 1500uF Panasanic FC caps but no luck. Can I use Samsung 2200uF instead? The MUR860 diodes did not look like the real thing either. I am planning to make the amp on a veroboard. I do not have a PCB source yet. There do not seem to be many DIY from this part of the world on the forum. Well, I am prepared to do the leg work and will post details of shops etc. Once again thanks for you detailed reply.
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Old 27th April 2004, 05:53 PM   #6
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You need to first find out if you really need those components and how they make a difference. I for one say there is no difference, but lots of others beg to disagree. In any case, since you're a beginner, and we all make mistakes sometime, it's probably wiser to stick with cheaper components and use whatever is available. Once you get the hang of it, go ahead and splurge on Panasonic caps or whatever else is the flavour of the month.

As for diodes, there have been lots of comments about how diodes introduce switching noise. Often, capacitors are used to suppress this noise. Using a high-speed diode will only make this noise worse, and in the bargain, introduce no benefit electrically. Psycho-acoustic (more psycho than acoustic, if you ask me) effects may still exist, though.

Veroboard: problem with that is that most chip amps pins don't lie on 0.1" centres, so you'll have to carefully bend the pins.

There actually are plenty of folks from India here, but all seem to be mysteriously silent... *shrug*
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Old 27th April 2004, 06:16 PM   #7
sunil is offline sunil  India
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Smarcher,

I'm buying a kit from Brian for Rs 2100/-, the basic version. This includes postage to India. You need a cheapo case & transformer after that.

Why don't you do the same ?

cheers,
sunil
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Old 27th April 2004, 06:22 PM   #8
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Quote:
Originally posted by sunil
Smarcher,

I'm buying a kit from Brian for Rs 2100/-, the basic version. This includes postage to India. You need a cheapo case & transformer after that.

Why don't you do the same ?

cheers,
sunil
Hi Sunil
What is your mode of payment? What about customs?

Sudeep
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Old 28th April 2004, 03:46 PM   #9
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Guys my appologies for interruption in this thread.
My honest suggestion for SUNIL would be, to learn a little more about microchips, amplification and gainclones, however purchasing a full kit doesn't serve the purpose of Do It Yourself philosophy, as you learn nothing out of it just assmeble or solder and put it together.
No offence.
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Old 28th April 2004, 04:51 PM   #10
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I tend to agree with abidr, you dont learn too much (except soldering, maybe) by buildong a kit. For what it's worth, my 3886 amp board + components cost about Rs 200 each, excluding the ICs.
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