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Old 16th January 2013, 02:46 PM   #21
Kitax is offline Kitax  Latvia
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perfect ^^
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Old 16th January 2013, 03:41 PM   #22
Kitax is offline Kitax  Latvia
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ok now rectifying...
SI-D 200V 8A/80Ap 10ns how do you think? its around 0.70$ do you think its an overkill?
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Old 16th January 2013, 04:28 PM   #23
Mooly is offline Mooly  United Kingdom
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Not overkill

There are many choices,
GSIB2560-E3/45 - VISHAY GENERAL SEMICONDUCTOR - BRIDGE RECTIFIER, 25A, 600V | CPC

or this style,
GBPC3504 - FAIRCHILD SEMICONDUCTOR - BRIDGE RECTIFIER, 35A, 400V | CPC

Everyone has there own ideas... I would suggest somthing like two 4700uf to 6800uf reservoir caps and also a simple snubber network of a 0.1uf 400vac poly cap in series with a 4.7 ohm 1 watt resistor connected across the combined secondary winding of the transformer (so that is across the input to the bridge)
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Old 16th January 2013, 04:56 PM   #24
Kitax is offline Kitax  Latvia
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heh... diode bridges cost about as much as a diode :P well that means i dont have to make one myself
http://www.datasheetcatalog.org/data.../250526_DS.pdf
it says max current with 300cm^2 fin is 10A... if i devide 300cm^2 by the 10A, i get about how much cm^2 i need to cool that current, dont i? (i know it would be really rough, but if i round it up, i think there shouldent be a problem...)
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Old 16th January 2013, 05:59 PM   #25
Mooly is offline Mooly  United Kingdom
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You won't have a problem with that. You'll find for normal loud music from the amp that the bridge is running cold.
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Old 16th January 2013, 06:16 PM   #26
Kitax is offline Kitax  Latvia
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really? i was certain, that i would need a heatsink... are you sure? :P
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Old 16th January 2013, 06:21 PM   #27
Kitax is offline Kitax  Latvia
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could you draw the schematic?

i was thinking, that one or two large enough caps would do the trick...
also i know that there are caps before the bridge sometimes... i wanted to ask in wich cases... i guess thats for safety, so it doesnt spike, am i right?
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Old 17th January 2013, 06:33 AM   #28
Mooly is offline Mooly  United Kingdom
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Lets just go back a bit...

Designing an amp for 100 watts or even just 40 watts RMS and designing it so that it can supply that on a continuos basis is a whole different ball game to a nominally specified 40 or 100 watt amp that would be used for normal domestic listening. Heatsinks, transformers etc need to be much larger. Most amps you buy fall into the latter category in that they are for domestic use. Its a big big difference you have to understand.

So for "normal" use your transformer and bridge are fine. The bridge (if its a block type) can be bolted to the chassis if you wish.

Caps on or before the bridge are to stop "ringing" caused by the commutation of the bridge as it comes in and out of conduction... remember I said earlier that it was non conducting for most of the time... it is that switching each cycle that can cause the ringing in combination with the inductance of the transformer.

One cap and one resistor is all you need across the input to the bridge.

There's nothing to draw really. It's just the basic transformer/rectifier reservoir cap arrangment.
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Old 17th January 2013, 02:11 PM   #29
Kitax is offline Kitax  Latvia
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Click the image to open in full size.
here... i drew a quick sketch... this is what i call basic transformer/rectifier reservoir cap arrangment. you said something about a rezistor... and what caps should i use...
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Old 17th January 2013, 06:01 PM   #30
Mooly is offline Mooly  United Kingdom
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Like this. Use around the values suggested earlier such as a 0.1uf and 4.7 ohm.

Grounding is SUPER SUPER important and makes or breaks an amplifier.

Read this

3 stage LIN topology - NFB tappings?


3 stage LIN topology - NFB tappings?
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