Some people might like a Vbe multiplier onboard with various configurations. I like the one at this link but am open to others.
http://www.tcaas.btinternet.co.uk/jc-3.gif
There is a good discussion of alternatives here:
http://www.hagtech.com/pdf/vbe.pdf
http://www.tcaas.btinternet.co.uk/jc-3.gif
There is a good discussion of alternatives here:
http://www.hagtech.com/pdf/vbe.pdf
dshortt9 said:Some people might like a Vbe multiplier onboard with various configurations. I like the one at this link but am open to others.
http://www.tcaas.btinternet.co.uk/jc-3.gif
There is a good discussion of alternatives here:
http://www.hagtech.com/pdf/vbe.pdf
I can make place for such VBE multiplier. It's easy to convert it to multiplier that I used on my first LM4702 PCB (jumper + NPN transistor instead of PNP).
This is only a draft. You can see FETs on this schematic but there is a place for TO247/SOT93 transistor with ECB pinout.
http://www.audio.webd.pl/pdf/monster_amp.pdf
http://www.audio.webd.pl/pdf/monster_amp.pdf
Like I have said before, I disagree with the National guys saying you don't need a heat sink on this chip. I have run it without cooling for a while, but I don't think it is a good idea.veteran said:dfdye, maybe it won't be much bigger I can place transistors in front of LM4702 (mine is running quite hot so I will need a little heatsink for it).
Oh, and no surprise that the board will be big!
My prototype output boards have been larger than I would have wanted but I think with a separate board you can be a little more efficient with the layout. Since you are working with one board, I can see the potential problems. Good luck! I am sure you will get something good.
BTW, I think you have inspired me to try Mosfets with your board.
That looks like a great start, but with my limited experience, I have to ask why you have two transistors (T1 & T50) when most of the designs I have seen/used only use one. This is not questioning whether it will work, but I simply don't know the answer.veteran said:This is only a draft. You can see FETs on this schematic but there is a place for TO247/SOT93 transistor with ECB pinout.
http://www.audio.webd.pl/pdf/monster_amp.pdf
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I moved my test board on a bigger heatsink. It's time to order some Toshiba's transistors
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
That looks like a great start, but with my limited experience, I have to ask why you have two transistors (T1 & T50) when most of the designs I have seen/used only use one. This is not questioning whether it will work, but I simply don't know the answer.
I thought there might be some advantage but after further thought I can not think of any. Works the same as one. Looks better on paper?
I thought there might be some advantage but after further thought I can not think of any. Works the same as one. Looks better on paper?
Work in progress. Board will be big... but not to big - about 130x120mm. Power transistors on the left and right edge. I added emiter resistors for PNPs.
Dshortt9, if there is some place why not try it
Dshortt9, if there is some place why not try it
An externally hosted image should be here but it was not working when we last tested it.
Quick question: What mosfets are you using? I am about to drop an order in for some other stuff and I figured I would play around with mosfets since they seem to be in the mix and working well.
Thanks!
David
PS What PCB software are you using? I have hit the size limit in the free version of Eagle and am looking at alternatives before I bite the bullet and buy a full version of Eagle.
Thanks!
David
PS What PCB software are you using? I have hit the size limit in the free version of Eagle and am looking at alternatives before I bite the bullet and buy a full version of Eagle.
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