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Old 27th October 2005, 11:03 PM   #21
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Hello

I might get some of these chips !!

Upon this & that, I will start designing a PCB for this nice thingy, I will post the design of the PCB asking for your opinions and suggestions to make it as blameless PCB design as possible for the LM4702.

Just wish me good luck...
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Old 27th October 2005, 11:19 PM   #22
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Good luck
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Old 28th October 2005, 09:22 PM   #23
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I was just thinking, if these are going to be like $5 or $6 it really wouldn't be worth it.

IMO, if it's only replacing the first and second stage of a typical lin amplifier, then it's only replacing a few resistors and maybe 5 transistors, which would cost you ,mmm, maybe a dollar.

I could be wrong but I don't think I'd pay for something that simple to make.

The're like a 200v opamp with no output stage, and while .005% d is nice it's not hard to attain with discrete componets.

Just a thought.
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Old 29th October 2005, 04:52 AM   #24
AJT is offline AJT  Philippines
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Default pcb group buy

@metal,

are you designing just the chip part pc or is it going to have the output devices as well?

if there will be a group buy for pcb, please count me in!
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Old 29th October 2005, 07:23 AM   #25
javven is offline javven  United States
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I'd definately be interested in this. I'll have to be the tail-end-charlie, though. I'm certainly no developer.

Leaders of the pack, please let us know just how much heatsink you need for a given application....
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Old 29th October 2005, 07:30 PM   #26
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Hello


I am designing the whole thingy in deed, so the PCB will contain one LM4702, two driver transistors and four output power transistors, also the "diode" transistor...

I 've concluded that it will be a better idea to be able to change the driver transistors, that will yeild the flexibility of having as many output transistors as the designer wants. For now, I will only include four output power trnsistors.

I have finished designing the library of LM4702, I will also design a library for the output power transistors, I will have MJL series.

For now, here is the library for LM4702, guys who use Eagle and are interested in this project, shall see this library and make sure its absolutely mistake free...

I also might omit the driver transistors and use power darlington instead, I am still confused on which one to go with...

Good LM4702 day !
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Old 29th October 2005, 10:38 PM   #27
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Hello

I have found these complementary darlington output power transistors to be a really good choice. I don't know if they are available in my country and other countries, but I will try to find out tomorrow.

MJ11031/2 complementary darlington output power transistors are rated at much higher power, but they are intended for general purpose audio power amplifiers, I don't assume they will be as good as those transistors that have transition frequency of 30MHz....

2SD2449

2SB1594


Let me know if there are any other suggestions for the darlington output power transistors that are as excellent as these and have transition frequency of 25MHz or higher, but rated at higher operating voltage and power.....
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Old 30th October 2005, 12:15 AM   #28
AJT is offline AJT  Philippines
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for pa duties, hte mj11032/33 complements will suffice imho!

nice to have ouptu trannies expandable in groupd of 4's

how about dicrete drivers and outputs?

thnaks,

tony
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Old 30th October 2005, 12:42 AM   #29
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Bob,
What make and model of stereo microscope do you have? I need to start using one myself.
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Old 30th October 2005, 01:26 PM   #30
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Default Microscope

Hi John:The scope I'm using is quite old and probably not available,it has 1x to 3x manification and is more than adequate for soldering SMD devices.

Regards Bob C.
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