Use a 10mm hex standoff for the nylon screws, not a nut.  Gives much better grip.  As for the locking washer, I use the ones with external teeth for a proper bite. 

I would use the ceramic and extend the transistor legs. 

Kerry, are the switchers +/- in a single unit, dual-mono, or one switcher per polarity?

They are single output units but the outputs can be tied together to form a split supply.  I've tried it a number of times with no issues at all. 

The problem I have found in the past is the noise spectra (between units) differ when doing this with switching supplies, and they don't correlate in a way where the usual circuit topology will cancel such things out. It's clearly visible on a FFT. Granted my experience is at much higher currents than here, but I would look for this when doing the final measurement of the amp.

Good point and something to look out for.  I'd prefer a dual output unit for this reason but one can never be sure if it's not just two singles inside the potted chassis. 

Does any kind person here have a 10k A-taper TKD 4CP-601 pot you'd be willing to sell me? (I could order from Japan, but I don't feel like waiting 6-8 weeks for it to arrive...)

Anyone have PCBs available for Dynalo Mk2 version 9? Also interested in some GRLV boards but not super important.

Otherwise I need some advice producing PCBs. My plan is to use EasyEDA. After looking at this zip file;

gilmore.chem.northwestern.edu/boards/kgdynalobal9.zip

I see that there is a side board for surface mount components. I am fine going with the THAT340 chip so I don't need this. If I only need the main board do I just submit the file as-is, but leave special instructions? Or do I need to edit the gerber to exclude the side board? What dimensions should I give? My planned specs are with 2oz copper and 1.6mm thickness.

that board is 5.47 x 3.04 inches

 

I have a general question on sharing info. If I reverse engineer a product and draw an electrical schematic based on it, are there any legal repercussions against publishing said schematic? If they already have a schematic and I scan it then I can see an issue, but if it's my own drawing then I am not so sure.  Same thing goes for the PCB. If I use their exact same layout then I can see an issue but not if I make a different layout.

reverse engineering a product has been declared to be legal in the usa. see landmark rulling Emulex vs digital equipment corp. publishing a schematic that you have done is also legal. If you have an original copy from the manufacturer it is not legal to publish it. I don't know about copying an exact circuit board layout. Likely if you have the original gerber files and modify them, probably not a great idea. But if you layout a board from what you see, probably acceptable. lifting code from on board microprocessors may be an issue.

Speaking of something similar, I always wanted to do something similar to Krell's iBias and I'm nearly halfway there with the temperature control aspect of it. When I'm done I should be able to change a setting for desired maximum temperature remotely through RPi and have the bias auto scale to be just under that temperature. Got any tips in implementation of this and how hard would it be to add the output current sensing part of it?

you want to use one of the linear isolators to drive one side of the bias circuit.

I have access to a few thousand NOS Toshiba 2sj103, 2sk373, 2sk709, 2sj104, 2sk30, 2sk170, 2sj74 fets, if any of you guys need some or bulk feel free to send me a PM. 

Also have a supplier from Japan who can supply 2sj109 GR's. I know Kevin will never let his stock go :).

I'm trying hard to also obtain the harder to get for the T2 build 2sk389's fets. 

Edited September 10, 20169 yr by DefQon

Why not just match some 2sk170s or use a LSK389?

I'd be interested in some 2SJ74s depending on grade. Or maybe some 2SK170s in addition, though I still have a number of those in BL grade IIRC.

^ Same.  That and the price.

+1. Interested in SJ74 and SK170.

 

//UFN

Here's what it costs from my source:

2SJ74-BL @ $0.90 each 
2SJ74-V @ $0.90 each 
2SK170-BL @ $0.90 each 

GR grades are a bit harder to get in bulk at an appropriate price but I'm trying to haggle another supplier for roughly the same as the above.

Edited September 18, 20169 yr by DefQon

Would be interested in a pic of the SJ74s before I commit, but YGPM anyway 

 

//UFN

Can anyone look at the CAD files and give me an idea of the maximum board thickness these connectors can be used with?

http://www.te.com/usa-en/product-1-770967-0.html

Also, laying out a simple unregulated power supply, if anyone is interested, details here:

http://www.diyaudio.com/forums/group-buys/297124-ic-yafwpsu-yet-another-firstwatt-psu.html

Can't read the CAD files (no software), so no help there. Datasheet says 1.57mm/0.062 which I'm sure you saw. You have some interesting projects going on!

Can't read the CAD files (no software), so no help there. Datasheet says 1.57mm/0.062 which I'm sure you saw. You have some interesting projects going on!

I saw that, but it said "recommended piercing plan". I have the part and it's really hard to measure. It could probably work with a slightly thicker PCB. I am thinking Kerry used these connectors and perhaps he used a > 1.57mm board and can provide some insight.

3 hours ago, luvdunhill said:

 

Can anyone look at the CAD files and give me an idea of the maximum board thickness these connectors can be used with?

 

I followed your link and opened the " Product Drawing "

it says 3.68   & 1.0 dia   for pins

there is no dimension given for the plastic mount clip but looks like half of the 6mm total so 3mm

my CAD gets the size wrong so no help there

Right, but you have to subtract the small standoffs as the entire part isn't flush to the PCB. This makes that 3mm smaller.

In the PDF I have open the measurement is from the bottom of small standoff to tip of solder pins...

isn't the 6mm clip part made to go through the board?

http://www.te.com/commerce/DocumentDelivery/DDEController?Action=showdoc&DocId=Customer+Drawing770967GpdfEnglishENG_CD_770967_G.pdf1-770967-0