I am not an expert on Jeff Rowlands nice stuff, but if I recall correctly, he don't use DC-servos, but trimmer to fight the dc-offset issue. If this is correct, it means that the OPA213X, that "jacco" is talking about is for something else (most likely some kind of buffer/gain stage).
(and why is he in the need for a SSM2141, if the has an input tranformer ???)
Have fun
Thomas
(and why is he in the need for a SSM2141, if the has an input tranformer ???)
Have fun
Thomas
Wow! 
Here i go on 1 week of vacation and lots of nice answers and pics.
tlmadsen:
Im not sure i understand you correctly here:
"You are right about the ground track if you connect your speaker (-) straigt to your PSU. However having low-resistance ground tracks/path is always good for your design.
"
On the Bpa 200 design the + of the speaker is connected to the parallelled pair (noninverted) of 3886 and the - is connected to the inverted parallelled pair. Where does ground or PSU come into the speaker?
This is a serious question, i cant see where either ground or PSU comes into the schematic
Best regards
Nicks
Here i go on 1 week of vacation and lots of nice answers and pics.
tlmadsen:
Im not sure i understand you correctly here:
"You are right about the ground track if you connect your speaker (-) straigt to your PSU. However having low-resistance ground tracks/path is always good for your design.
"
On the Bpa 200 design the + of the speaker is connected to the parallelled pair (noninverted) of 3886 and the - is connected to the inverted parallelled pair. Where does ground or PSU come into the speaker?
This is a serious question, i cant see where either ground or PSU comes into the schematic
Best regards
Nicks
M10 with 3 dif. PSU's
Hi Everybody
I was not the most active student in French at High school, but look/reading Jacco’s pictures it is not at all clear to me that the OPA2134 Jeff Rowland uses are for the servo. Since each LM3886 have its own trimmer I am pretty sure that the OPA2134 used is for “something else” (buffer ??).
Anyway, the picture of the M10 from Jacoo are very nice and it does make you start to “dream”. My dream would be to make something similar to the M10 (not to difficult). This would then have different PSU-options:
A. Regulated PSU. Could be based on LM3886 and use the same PCB as the “M10” with a little bit of “cleverness”.
B. Standard unregulated PSU (Transformer, bridge+ capacitors)
C. PSU made of SLA-batteries. Something like 2x3x 12V/7A would make a VERY powerful PSU. You would only need some kind of small charging circuit /auto on/off/charge. This would only require a small transformer compared to solution A or B.
A SLA-based PSU actually makes more sense that you might think. The gives you the same “stiffness” as the regulated version, but much less complex and price wise it is compatible with the unregulated version. I think you can buy a 12V/7A SLA for around US$ 20.-
…………….So many dreams…………..so little time.
Have fun
Thomas
Hi Everybody
I was not the most active student in French at High school, but look/reading Jacco’s pictures it is not at all clear to me that the OPA2134 Jeff Rowland uses are for the servo. Since each LM3886 have its own trimmer I am pretty sure that the OPA2134 used is for “something else” (buffer ??).
Anyway, the picture of the M10 from Jacoo are very nice and it does make you start to “dream”. My dream would be to make something similar to the M10 (not to difficult). This would then have different PSU-options:
A. Regulated PSU. Could be based on LM3886 and use the same PCB as the “M10” with a little bit of “cleverness”.
B. Standard unregulated PSU (Transformer, bridge+ capacitors)
C. PSU made of SLA-batteries. Something like 2x3x 12V/7A would make a VERY powerful PSU. You would only need some kind of small charging circuit /auto on/off/charge. This would only require a small transformer compared to solution A or B.
A SLA-based PSU actually makes more sense that you might think. The gives you the same “stiffness” as the regulated version, but much less complex and price wise it is compatible with the unregulated version. I think you can buy a 12V/7A SLA for around US$ 20.-
…………….So many dreams…………..so little time.
Have fun
Thomas
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