Kerry

I used two pins per coil. Here's the tech note I followed: http://www.maximintegrated.com/en/app-notes/index.mvp/id/3288 That's a lot of T2's in the wild

It must nice to have a Birgir for that I've used these relays, G6KU-2F-Y-DC4.5, controlled by the MAX4821EUP in another project. Very simple circuit and works perfectly. The relays are much smaller than the original ones. Going to all SMD parts would help a bit as well.

I've decided I'm going to build a smaller version of Kevin's digital attenuator boards and add an MCU and small OLED display. I already provisioned the 5V on the PSU (instead of my original thought to do 12V). I've got a .333mA transformer and I'm trying to keep it all around 230mA, which I think I can do. I'm also going to add a USB DAC. I'm really liking what AMB is doing with the Zeta1. Since I want balanced output, I can't use the gamma 1.5. The gamma 3 is more than I need for this and much more than I could fit. I'll likely just keep it to USB (no SPDIF). I'm also likely going to use an ASRC (same from the Gamma2). I've already done this in another DAC. I'm also going to build in some isolation for the I2S and I2C (if I decide to go with software mode on the WM8741). I won't be able to cut dual mono not enough space or power. I had a very cool thought that I should also add a built in digital volt meter. Besides being very cool, this could help adjust the bias between the +/- for each channel. I've got a preliminary design and so far it seems to work in LTSpice. It'll have a range of +/-30V, which is more than I need. I'm going to go with a single knob/encoder with a momentary switch for volume control and to run through the menus.

I have some sc4686's that I was going to use but the hfe were 20 or less. The sc3675's that I used were 63. I wanted it to be higher so I went with the latter. I also have some 2sc3840's (I've used these before) that have a small exposed tab like the sa1486's. Might have been a better choice (pin out is reversed so you'd need to flip them). Nopants - I've seen you post these parts before. What is the part number. I don't mind being extra cautious. Edit: The FJPF2145 seems like a good choice.

It's .13" or 3.3mm. That should be plenty. Good guess Marc.

Here's what it will look like in the chassis. This is looking at it from the bottom of the amp.

Thanks for the comments The board size is 5.9" wide and 6.25" deep. The heat sinks that mount to the sides of the board are from heatsinkusa. They're the low profile ones and are a half an inch thick. I'm leaving a .05" gap on either side of the board so the width will be exactly 7" with the sinks.

I used a larger capacity one for my Blue Hawaii and I've used this particular one in a guitar amp I built with no issues. The transformer here is a 100VA and it's the only thing running through the SSR. Power draw for the amp is about 28VA against the HV side of transformer not accounting for loss.

I finally got around to the power supply for my mini-kgst. I was able to get the +/-400V with delay, filaments, +/-15V and a +5V supply all on one board (5.9" x 6.25"). Here's what I came up with... Here's the 3D models from DipTrace. I did all of the non-standard 3D component models myself. I'm getting good at it. I ordered the wrong size caps for the HV supply . I'm going to put in another order and should have it up and running shortly. I redesigned the timer circuit because I'm using it with a solid state relay. There was a short ON burst in the older one that would turn on the relay for a small fraction of a second. This one keeps the output low until activation. I've been testing it for about a month and it seems to work well and is stable. It was a combination of reading the datasheet for the LM555, modeling some ideas in LTSpice and then testing on the bench. I'm usually careful, but made a mistake on placement of the charging capacitor. I had to move it, but got luck and it was a fairly simple surgery. I'm looking forward to getting the caps for the HV and testing it out the rest of the board. All in all I'm happy. Most parts are fairly accessible and it seems like I'll be able to get to them if need be. This board will mount under the top panel of the amp in the back. The transformer will sit on the top above the top panel directly above the supply. I'm using the Antek 100VA 350V transformer and steel case. More to come

Very nice build. Love the look.

Nice work as always! I was enjoying the white faceplate, but this has such a bad boy look

Nicely done

Nice:) Too many projects in front of this for me. Maybe around Christmas time.

The 10M90S on the top center is not centered properly. It's about 1/10th of an inch to the right. I haven't carefully checked the rest yet. Edit: never mind, just looked again and it looks good now.

Nicely done

Interesting:). That's what I was hoping you'd say. I may need to pull mine out and rewire as well.

I'm guessing that will change the sound signature. Kind of like Marshall vs Fender. Have you built one yet?

It would be nice to get Q32 on the main heat sink as well.

Oh crap! I'm feeling the need to build this. haven't looked closely yet, but you still have some transistors labeled with 2SC3675. were you thinking of doing this as one or four boards?

Nice build! Now just hang out and wait for the 009s. Enjoy:)

Nice. I like the single chassis approach.

Now that's DIY. Yeah, 1000v

Nice work!

I turn on my +/-15 supply before I turn up the HV and have had no issues. You should be fine to test the LV first. Don't do the reverse though.

Nicely done. It looks beautiful!