gepardcv

What is supposed to go on the board to the right of the AC inputs? The two notched rectangles with holes labeled AC1 and AC2.

Very nice. Thanks. I like my current Dynalo a lot, but would probably build another with the Golden Reference PSU.

Are you testing the new Dynalo boards, the Golden Reference, or both?

Fascinating. For those of us a little late to this party, what is the purpose of this..? I found on this thread from 2010, which makes it sound like the purpose of the Cyclotron is to make a fully-complementary, fully-symmetrical electrostatic amplifier. Is that right?

Looks like you changed the kgdynalobal5 boards, the originals with MPSW parts, which have been used in quite a few builds with no apparent problems. What does this change affect (and how did you notice the missing lead)?

Yes, I want to go all-out with the Carbon. Will start serious work on it once I wrap up the KGST and mini stereo KGSSHV — all parts now ordered and inbound for those two.

I think that a build will fit in a Modushop Dissipante 2U 300 with stacked amp boards, but didn't actually lay it out to double-check. Not a small box, but not monstrous, either. A fully-custom chassis should allow more space saving.

Would it be bad to stack the two carbon amp boards on top of each other (perhaps slightly offset)? That would make it possible to use a smaller case than if they are placed side-by-side.

Do it!! (That way, I'll know for sure if PJ is shipping the revised models before I place my own order. )

A lot of power inlets (like the Schaffner FN1394-10-05-11 or FN284-10-06 or FN9290-10-06) hold two fuses, one on the hot side and one on the neutral side. This seems strange to me: if the fuse on the neutral side blows, the circuit will fail live. On the other hand, if the amp is plugged into a reverse-wired outlet (pretty likely IMO, I don't trust any house wiring to have been done correctly), then both sides are fused just in case. Thoughts on the tradeoff?

Do the SiC MOSFETs need to be matched at all for either the PSU or the amp boards?

Now that will be a fun challenge to fit into the same box as two carbon boards. Definitely putting this into the project queue.

Ditto, but McMaster doesn't have all sizes and types of screws available in black. I planned to look into sending plain steel screws sent out to get powdercoated as a custom job, but never got around to it.

I didn't realize the RN60D is a relabeled CMF60! From the datasheet: The CMF60 is rated for 500V, and its power rating ranges from 0.5W at 70°C to 1W at 125°C. That makes the RN60D suitable for almost everything we build here, doesn't it (except the T2)? @kingofsnake: That looks great! I used Mouser part 584-OP27GPZ in my Dynalo, it worked well, so I plan to use it here also.

They're milspec, so that supposedly doubles the rated power to 1/2W.

Perfect, thank you Kevin and Birgir. Now for resistors: I plan to use RN60D throughout. Is there any place I should use Xicon or other parts rated for more than 300V?

A couple of clarifying questions about capacitors on the KGSSHV mini stereo board: 1. For the 5pF capacitors, there is no voltage marked on the silkscreen. Would this one, at 100V, be adequate? 2. There are two rectangular 1uF capacitors right next to the servos, also without voltage marked. Can I just use the same 1uF 450V Panasonic part I found for the explicitly marked caps in the center of the board?

Just to double-check my sanity (or blindness): the KGSSHV mini stereo board doesn't have servo bypass jumpers, right? I feel like I'm playing Where's Waldo. It's a very pretty board, but super-packed...

Is there a source for matched 2SK170 transistors other than AMB? AMB says those JFETs are all reserved for people buying his own boards (which I'm not). I don't fancy getting buying dozens from bdent just to get a handful of matched pairs. Do you trust eBay sellers who claim to have matched (like this or this)?

There are two zeners on the PSU board, connected to the FQPF8N80C MOSFETs. The silkscreen shows them as 24V, but a couple of BOMs floating around (this thread) suggest using TZX12D-TR, a 12V diode. I plan to follow the silkscreen, but just thought I'd double-check.

How have you modified your SR-007?

I found this one in the meanwhile: http://www.mouser.com/ProductDetail/Aavid-Thermalloy/531302B02500G/?qs=/ha2pyFaduiSqs76HCxkXcUvznuhemcjJ96w0ajgr6U= The fins don't look the same as on the silkscreen, but I can't imagine that matters. The dimensions all look reasonable. If I'm reading the air flow graphs correctly, it has slightly better dissipation performance than the Farnell 637-25ABP at the same height (2.5").

I haven't done any investigation into Carbon boards yet, but have you tried contacting iTEAD (http://imall.iteadstudio.com/open-pcb/pcb-prototyping.html)? I've had pretty good luck there. There is no explicit 3-layer option, but there is 4-layer. I would open a support ticket, attach the Gerber zip, and ask if it can be produced as a "prototype" and which checkout option to use.

What volume pot are you using now?

Perfect, thanks everyone! Next, a question about heatsinks. I've been comparing various Aavid models, and found three models with identical footprints: - http://www.aavid.com/products/standard/530002b02500g(2.5" height, 2.6 thermal resistance) - http://www.aavid.com/products/standard/529902b02500g(2.0" height, 4.5 thermal resistance) - http://www.aavid.com/products/standard/529802b02500g(1.5" height, 3.7 thermal resistance) The largest sink has the best thermal resistance; seems reasonable. But the 1.5" has a better thermal resistance than the 2.0"? How can this be? They seem to be made of the same material and look otherwise the same.