| Aug 4, 2004 |
Made a minor update to the 3.0 circuit;
published "3.0E" in the archive section.
The difference lies in the realization that there was no need for an input
buffer OP. |
| June 27, 2004 |
Minor cleanup here and there. There may be some
related developments of a "reference DIY class D design" going
beyond my 3.0 circuit over at DIYaudio.com.
Check out this
thread for instance. |
| Feb 2, 2003 |
Finally updated the site to reflect that the 3.0
project is ready for now... Maybe one day I'll crave for even more power,
or find some issue(s) that warrants some improvement, and then I may start
a 3.1 project, who knows. |
| June 11, 2002 |
Added draft PCB layout for revision 3.0D on the archive
page.
Check it out, and if you intend to use it, let me know what is missing! |
| June 9, 2002 |
The design description
has undergone a significant rework, to capture the new "state"
of the project, as well as some tests & measurements performed this
weekend. (Now 100W has been sustained/tested in 8ohm @100Hz, with an
efficiency around 90%. See the design description for details.) |
| June 5, 2002 |
Hooray! The two new channels work! I still have
some issues with the power supply and/or the protection circuit in the new
casing for the latest amplifier. But when bypassing the protection
circuit, the two new channels do sound great :-) This should mean that I
can focus more on documentation and publishing of PCB layout etc. in the
week(s) to come. |
| June 2, 2002 |
Updated the archive page with a picture of the
latest PCB design. I've only built one PCB (=one channel), but it alone
does seem to work quite well with the full power supply voltage. I'll will
build another PCB before I assess the sound quality though. (It's already
etched and drilled, so it shouldn't take too long.) |
| May. 25, 2002 |
Updated links section.
Work is ongoing on yet another PCB design. Have patience :-) |
| May. 7, 2002 |
The 3.0 schematics and design
description have been updated with more info on the second and third
PCBs. |
| Apr. 23, 2002 |
The 3.0 schematics and design
description have been updated to correspond to the second PCB. I have
added DC stability on the outputs as well, which also has led to a slight
problem relating to the order of shut down of the power supply voltages.
More work to do... |
| Apr. 16, 2002 |
The 3.0 design is now entering beta testing; two
channels are now running together, producing quite enjoyable sound/music,
at power levels way beyond what was possible with the 2.1 design. The
efficiency of the circuit on the new PCB also seems quite acceptable - the
heat sink/casing only rises a few degrees in temperature after hours of
playing at high levels (several tens of watts at least). I'll follow up
with more concrete measurements/figures as soon as I can. |
| Apr. 14, 2002 |
The 3.0 schematics and design
description have been updated to correspond to the second PCB. I'm
trying to get the output filters right before even trying to test at high
power this time.. |
| Apr. 7, 2002 |
The second PCB is ready and works to the limit
I've tested it so far (which doesn't include maximum power).
See the new picture on the archive page :-) This PCB embodies a slight
variation of the 3.0 design as currently shown on the available schematic;
I've taken the LM311 comparator circuit from the 2.1 design. This renders
a switching frequency of around 800-1000kHz, and the circuit seems much
more stable than the previous attempt with the LT1016 comparator. These
findings will be better documented in the design description later. |
| Mar. 31, 2002 |
A new PCB is underway. The first one had too low
efficiency and reliability at high output powers... |
| Feb. 24, 2002 |
The
tentative 3.0 design on PCB is being tested and tweaked. 100W in 8ohm can
be sustained, albeit at a somewhat low efficiency (around 70%). The 3.0 schematics
has been updated to reflect the latest (minor) changes. Testing/tweaking
will continue next week (with focus on raising efficiency). |
| Feb. 17, 2002 |
The
tentative 3.0 design on PCB now exists (one channel only though), and does
seem to work to the limited extent that I have been able to test it so
far. The 3.0 schematics and design
description have been updated to reflect the latest changes. |
| Feb. 11, 2002 |
The realization of the
tentative 3.0 design on PCB is progressing; preliminary tests indicate
that the design does measure up, but some small adjustments need to be
done. (Not reflected in the 3.0 schematics yet. For example, the switch
frequency was too high for the drive stage & MOSFETs I'm
using.) The major problem right now is getting two amp. channels on the
same PCB to coexist without disturbing each other... More will follow... |
| Feb. 1, 2002 |
More progress made on the 3.0
development; we now have a tentative design that may be good enough
for an amplifier supplied with +/- 50 Volts, or around 150 Watts in 8 ohm.
Comments or constructive criticism is highly encouraged, while I try this
out in real life to learn its behavior and limits! |
| Jan. 27, 2002 |
Some progress made on the 3.0
development; some test setups tried over
the last weekend indicate that I'm close to having a working solution to
the MOSFET driving problem. |
| Jan. 23, 2002 |
Updated the links
section. |
| Jan. 22, 2002 |
Added a historical description of my first class
D design. |
| Jan. 16, 2002 |
Added some more material (simulated frequency and transient
response) for the 2.1 circuit. |
