Kerry

Good point. It could be a cold solder on the ground pin. I don't recall if the jrc part requires a load but it's also a good idea.

What's the input voltage going to the regulators. Seems like they are toast, but I'm curious why you've had to replace so many times. There may be something else wrong. If the input voltage is the same as the output, then go ahead and cut the leads near the body. It's easier to de-solder that way. As a general rule you should not apply heat for more than about 3 seconds (4 is a max for me). Less is of course better.

I was looking for a part that I can only find in Japan on RS Components in Japan. The part is hn4c06j from Toshiba. I'm wondering if someone would be will to purchase and ship to me in the US. I was looking at a quantity of 100. Thanks in advance.

Money sent. Thanks.

Ran the update on the 30th and it locked out my network. I had Hyper-V installed and it messed up the virtual switch. Good thing I know something about computers and was able to fix this. I reported the bug to them. Otherwise, I've been running the preview for a couple of months and I like the push back to desktop mode. Even the Tablet mode is more consumable by Windows 7 users. Not as much of a context switch.

Agreed

In the models the 5.1 ohm resistor should have a cut off of around 112mA. At 20mA per leg you should be consuming about 80mA/84mA per rail. This should be sufficient. Also, I just wanted to mention that the LV rails consume less than 8mA per rail for the amp section. The op amp for the servo will consume a bit more (5-10mA) so you really don't need that much from the transformer. 100mA is plenty.

Yes, that is for a balanced board fully populated. The biggest swing will be in manufacturing costs and resistors. I assumed similar pricing to last time for resistors for the signal path. Then there are a bunch more high current resistors for the relays (32) that are relatively expensive. Volume will matter here as well. I also took the manufacturing costs and doubled it since there are double the parts of the single channel boards for the last run. This is not really a good assumption, but is a reasonable starting point. There are large setup costs for the manufacturing and we'll need to get decent volume to cover that. Long short this is a real SWAG

Also, looking at the price, I think we would be in the neighborhood of $180 - $190 for assembled units. That depends on a million things including volume. I just wanted to set the right expectation.

It's actually one board for two channel balanced operations. Pretty cool how small it is

I was thinking of about 20mA per leg with 4 legs for both channels. There is some additional current required on the negative rail, I forgot how much, but I used 22mA x 4 = 88mA per rail. I then multiplied by 4 which is a reasonable factor for power requirements on the transformer. Some would suggest 5x. So 88mA x 4 = 352mA which would give approximately a 250VA rating (not counting the LV of about 18VA). For the Blue Hawaii I use 350VA transformers and sometimes more.

I'd probably go to 350mA for each of the hv windings.

Agreed. Very nice!

The files are posted on Kevin's boards site. I've checked the boards, but wanted to test them so I just had s small run made. These would be great candidates for assembly as well. It's surprisingly inexpensive. I'm not sure if I would be up to running the group buy. It was quite a bit of effort. I would happily work with someone though.

On the original boards you set one relay at a time and cycle through them. All 16 take less than a quarter second. Given that, the current on the 12v line shouldn't go much above the 17mA per relay. You should spec for higher by about 4x just for fun. Since they are latching there is only a small quiescent current when they are not switching. I went back to look at some of the old posts and got nostalgic

The original boards will require a 12v supply for the relays. You can feed the uno from that as it has built in regulators to get it to 5v but you need to be careful how much current you consume off the 5v line. So you'll need just the 12v supply. I'll need to confirm the current requirements. The new boards require 5v to both the digital section and the relays. Each relay requires 116mA to activate. Technically you can switch all 16 at once, but you'll need to make sure your 5v supply can handle it. I would not take the 5v for the attenuator from the uno in this case though one supply could feed both.

I just ordered a few so I can test the board out I'm going to try using a hot air gun and solder paste for the MAX4820 chips since they have a pad underneath. Maybe see how that works for some of the other SMD parts.

For fun, here is a 3D rendering of the new boards... Edit: Don't let the size above fool you. These are 3" x 2". I think they should even be small enough for Birgir ​

If anyone is interested in the original group buy assembled boards. I have a set I'd be willing to sell. Please PM me if you're interested. Same price as the original group buy. They are the original 24K version.

Times are changing When we first looked at the resistor values, 1206 had the most matches. I don't mind 0805 and work with that all the time. Were you looking at the thin film? Edit: It might be harder to use the smaller resistors with the current layout.

I might have substituted some values based on availability. To long ago to remember. A number of Kevin's amps have 500k input to ground resistors into the fets so basically the attenuator will see the 500k. I probably used the default 1M though.

The final version of these boards did not have 2512 pads, though they do support through hole resistors.

If I remember correctly they were around $97 $99 ​per board. I'm going to review the new smt version of the board and order a couple so I can test it. EDIT: I just checked on the price of the original assembled boards. I have a set sitting in front of me that i'm putting into my BH build.

Kevin has a new version of the servo that he's using with the carbon. I can publish a link later

Wow Craig, that looks spectacular!