| luka |
I decited that I want to build D-amp too.So I will need as much help as I can get.This is the what I would like to build
There are probably a lot of mistakes that will need to be corrected, so here is where you guys come into play :).
Any help will be much appreciated |
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| luka |
| Any suggestions, ideas, comments,... |
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| gaspain |
what program did you use to design that circuit?
Looks nice |
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| luka |
| I used Circad 98 to draw this one. |
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| fredos |
Hi Luka
How did you find circad? Work well? I like it! Your design seem good, you will just dont need the startup circuit (Q2) at the output of your LM318. With clocked design, amplifier start automaticaly with first or second clock pulse. Boost too your bootstrap capacitor to 10-100uF with a 100nF low esr, this will avoid lose of signal at clipping on the hight side. V1 for offset is not nescesary because this topologie is closed loop, so auto 0V. Add to a 0.47uF 250V MKT or low ESR across +/-50V clossest as possible to your mosfet's. Pin 11 of your IR2110 to -50V too if you dont whant unexpected shutdown of the chip. Add too a 1n914 diode to clamp input of the 40107 to his VCC. A pull up on the base of Q1 will help too faster switching.
Your on a good way!
Fredos
PS look close to my amplifier schematics!
www.d-amp.com |
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| luka |
Fredos,
Circad works very well. For Circad I typed it in google and from there on you can DL it.
As for the circuit I think I did everything you wrote.If I didn't done it right tell me...
How big should be the triangle wave? A bit bigger than 0.7v ?
This is updated shema
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| fredos |
R19 should go to +5V and 1K. 0.47uF 250V on mosfet should go from drain to source...Otherwise, you will add noise on the ground! Just on PSU...Rest seem good, you could maybe short R18 to avoid noise picking...
Fredos
www.d-amp.com |
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| fredos |
I forgot...More small is your triangle wave, more open loop gain you will have, and less distortion...But more easy to pick-up noise! Place C4 as close as possible to U2!
Fredos
www.d-amp.com |
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| luka |
Ok I will correct 0.47uF caps. R18 is there because I will use some kind of shut-down, maybe it is to big. I will put 470 ohm, how is that?
As for R19, the transistor is PNP so if I put positive voltage on base I will help it to close faster, is that what you meant? |
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| luka |
I have done the correntions, but I think that 1k for R19 is a bit low, 3.3k would be much better I think.
If anyone alse see something that would be good to change, pease tell me. |
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| fredos |
C1 and C14...Not good! 1X 0.47uf between drain of upper mosfet and source of lower mosfet! 1K will match delay time for your R5 base drive resistor...
Fredos
www.d-amp.com |
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| luka |
Why do I need 1n914 for? |
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| zkaiser |
| quote: | | Why do I need 1n914 for? |
well, because if you don't use this clamping diode than you putting +5V more or less directly into logical gate which is grounded at -50V. This will at the end bring 55V voltage on 40107 input(s), and you don't want that.
So when you have this diode after voltage rise Va+0.6V , diode coducts and incrasing the current which will couse excess voltage dropout on R8, etc. . . .
PS
this is actually iraduio1 made of cheap componets but with sync. clock isn't it ? |
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| luka |
| Yea you could say so... I don't want it to be self-oscilating and use as less componets as possible, so that it works. And about those "cheap" componets.. I am not prepared to put 10~15$ for chip that it will perform not that much better if that... |
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| luka |
I forgot to ask:
What must / should be min/max duty cycle ? 5-95% ? |
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| Baldin |
Well as with any other amp, you don't want it to go into "clipping" :)
But will you build something in to control max dutycycle?
I have been building on a similar circuit, and I had to include some more deadtime. using IR2110 - IRF640/IRF540
Will you build it on a bread bord first?
Your level shifter (Q1) could be built somewhat faster using a common basis type, as has been described here some times.
Looking forward to hear how it works out ;)
Go for it :D |
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| luka |
hey
| quote: | | Looking forward to hear how it works out |
You and me both :D
I won't compicate circuit that much, I will just make sure with diods on input that it can't go there at least not with input signal being bigger than triangle wave.
I don't know yet if I'll build it on bread bord first, probably not. |
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| fredos |
You can limit duty cycle by the add of monostable (4528 I think) to the PWM signal of U2. This is very precise and easy. You can too put triangle wave amplitude over the clamping value of diode, but no precision. Anyways, at this power, you can go from 0 to 100% duty cycle without probleme...This is a clocked design! No worry about this except the hold on time of the 47uf on the bootstrap. If not OK, just put it bigger!
Fredos
www.d-amp.com |
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| luka |
| How could I create more dead time if I even need more ? |
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| fredos |
Artificialy with gate resistor...But you will need more fast discharging diode...Like 1N4150..
Fredos
www.d-amp.com |
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| darkfenriz |
| quote: | Originally posted by fredos
PS look close to my amplifier schematics!
www.d-amp.com |
Where are the schematics?
Adam |
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| fredos |
No more evolution?
Fredos |
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| luka |
There is but now is the time when I can't do much more with looking just schematic, so PCB has to be made.
OK I will put the various supplys for chips in schematic later this day. |
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| luka |
fredos
Will byw56 be ok instead of 1n914? |
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| luka |
| This is how it looks now... |
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| fredos |
Seem good, but dont like this drawing software...Lot of thing not clear...especialy if collector of Q2 is connected to your 40107...
Fredos |
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| luka |
With this software I will made the PCB, I just copied the shema you from before. Your eyes are good.Collector wasn't connected to 40107, but 40107 pin1&2 weren't connected anywhere, my mistake.
With what do you made PCBs (software)? |
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| fredos |
Circad for PCB and schematics....Fastest and best I have ever try!
Fredos
I will move to www.diyhifi.org
Too much newbies here that need to know how to add level to an amplifier and whant to promote their UCD mod...or to play the ''my caps is better than your's''....Tired of that! |
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