I am trying to post a picture of my b500 amp.may be sucessfull at this time.http://http://www.flickr.com/photos/57293718@N03/?saved=1
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Then choose a compression system to suit the type of picture.
PNG suits schematics. Jpeg suits photographs. You can experiment with a number of compression types to find what suits.
Compress the pic file.
Attach to your post.
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Regards
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it is in testing period:,only with +/-12 volts.after some time i will complete it.
anybody will please comment on my 2n3773 ,is it original ? i got it from junk.After cutting one i have seen the silicon chip,it is big in size.
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Your 2N3773 is original. Test amplifier with +/-12V rail voltage is wrong. Use 10R instead fuses or serial bulb 100W/220V in transformer primary for test, and use proper rail voltage.
Regards
rule of thumb for BJTs:
total output stage device power / 5
300W / 5 ~ 60W for 1 pair
However, that 5 divisor applies when significant second breakdown must be allowed for. The 3773 is almost unique in having an extraordinarily high second breakdown knee for a 140Vce0 device.
You can safely reduce the divisor to somewhere from 3 to 4 instead of the more usual 5 to 6.
The Crown DC300 used two pair, and was a bit marginal at 4R.
The DC300A used four pair, and was pretty hard to break.
With a good heatsink and foldback current limiting you could probably get away with only two pair.
Since the outputs are such a small part of the total cost of the amplifier, why not throw in another pair (or more)?
The DC300A used four pair, and was pretty hard to break.
With a good heatsink and foldback current limiting you could probably get away with only two pair.
Since the outputs are such a small part of the total cost of the amplifier, why not throw in another pair (or more)?
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you should not be using 140Vce0 devices on ~+-70Vdc
The normal mains voltage variations and the abnormal mains voltage variations will take the ~+-70Vdc to as far as +-60Vdc upto +-80Vdc.
The 3773 are not specified for use at 160Vce.
It is +/-70 volts without any load & in many posts in this thread it is suggested that you can use these with this supply.I am ready to increase the no. of o/p pairs but wants clear suggestion about this.
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AndrewT is correct, ±70V could be marginal in some countries and with some brands of 2N3773.
'In some countries' refers to how well the nominal mains voltage is regulated.
The spec sheet for the part specifies 140V total swing for forward biased operation. With proper test equipment they could be selected for higher breakdown voltages. I got lucky with a set that went into an amplifier running at ±85V, but these came from engineering stock at a major aerospace contractor.
The Altec 1270 used ±75V rails, and the parts list says selected 2N3773.
Back when I was designing consumer electronics for the world market I always allowed for the mains being 10% high, but I was told that for certain market areas that I had to allow for a 20% high mains voltage.
If you want to be absolutely sure, this would imply two pair on ±57V.
'In some countries' refers to how well the nominal mains voltage is regulated.
The spec sheet for the part specifies 140V total swing for forward biased operation. With proper test equipment they could be selected for higher breakdown voltages. I got lucky with a set that went into an amplifier running at ±85V, but these came from engineering stock at a major aerospace contractor.
The Altec 1270 used ±75V rails, and the parts list says selected 2N3773.
Back when I was designing consumer electronics for the world market I always allowed for the mains being 10% high, but I was told that for certain market areas that I had to allow for a 20% high mains voltage.
If you want to be absolutely sure, this would imply two pair on ±57V.