Category making things

Well, the PCBs from the group buy, MOSFETs (IRFZ24N /IRF9Z34N complimentary pair) and high-quality pots from AMB audio shop, and 7-pin PC mount sockets from TubeDepot have been ordered.

I still have to source some appropriate tubes (probably 12AE6 or 12AE6A, likely on eBay) and place the order for the bulk of the parts from Mouser. But the difficult things have been selected. :D

Soon and I will be on our way to completing some of the Millett Hybrid MAX headphone amps with MOSFET-based output stages.

I’m thinking I’ll follow Matt’s lead and mount mine on some sort of wood platform, surrounded by a cage. I’ll probably also incorporate an iPod dock / charger so I can use it where I use headphones most; on my desk at work.

UPDATE: Five NOS GE 12FM6 tubes purchased via eBay for US$20.50 shipped. These have a slightly lower amplification factor than the 12AE6/12AE6A tubes which most people seem to use for them (13.5 – 10 vs. 16.7 – 14.3), but I don’t think this will be an issue.

Now to order the first go-round of parts from Mouser, Digi-Key, and wherever else is needed to ensure that all required parts are in stock. Oh, and an FT232BM to replace the one I stupidly cooked last night.

Arraugh. I think I overheated the FT232BM in the x0xb0x. That is, the surface mount USB to RS232 chip which is used to update the firmware and such.

I had a really fine screwdriver tip (about the size of a needle head) and the iron was turned way down, but I had a little trouble soldering it, and when I was done it didn’t work. I think I need to get another one (at $4.95/each) and try again with the 1/64″ conical I’d used for other SMT work. <sigh> Unfortunately that also means desoldering the current part… At least I can do that. (Worst case I’ll just cut all the legs and remove them once at a time.)

Other than that, the x0xb0x is ready for its first flux removal, before I install the LEDs, pots, tactile switches, rotary encoder, rotary switch, etc. Then after I complete the rear panel it’ll be done. Oh, and once I fix the damned USB stuffs. It’s not needed, but if I’m going to sell it, it has to be working.

I think I’ll start building my second x0xb0x tonight.

This one has red PCBs, and I have all the parts I need to build it at home, including one final piece of custom artwork.

The only thing which will take a while is checking out the parts to be sure they all shipped, drilling the hole for the power switch, and painting the rear panel.

Completed Prototype PCB

Well, after about five hours of working this evening (after laying out the board in free time at work) I’ve finished the prototype PCB for the project I’ve been working on for a friend’s company.

As with the last few boards I’ve done, I etched it in the laundry room, as the laundry tub and large flat surface makes for a good place to work. (Photo of PCB being exposed.)

Then I drilled the board, breaking more PCB drill bits than I like to. Next came manual bridging of vias (which is a really awful chore), and then finally assembly. After I had it put together I powered it up, probed around for shorts, and generally confirmed that it wouldn’t explode.

Tomorrow I’ll confirm that the pinout of the board is as expected, and hopefully I’ll be able to deliver it at lunch time. If it works I’ll (hopefully) have some production boards made for them. I stayed late at work avoiding traffic and worked up a first draft of a mostly-SMT board layout, fitting in ~30mm x ~85mm. If I end up producing these boards I can see the final product being something like this, should I choose to do it SMT.

Hopefully tomorrow I’ll get to unpack the new baking stone, the new x0xb0x kit, and maybe just relax a bit. For now it’s bed time. Goodnight.

HMLiberator PCB v1.0
(Click for 600dpi version.)

Well, it’s done. I’ve ordered the first run of PCBs for the HMLiberator. While they are technically a prototype, these v1.0 PCBs should be also be usable as the final part. The circuit is pretty simple, and I’ve checked things over a number of times, and it all seems right. Now I just need to finish the software.

Thanks to Advanced Circuit’s $500 Free Promotion I was able to get a $500 credit towards one or two orders, making this entire order free. I’ve heard excellent things about Advanced Circuits, and due to the small tolerances on these boards I wanted to be sure they’d be done right. Also, should I go production on this item, 250 boards will only cost $1.94 each.

For now I ordered 12 boards, as any quantity from 5 to 12 were the same total price (price per board * quantity). With any luck I’ll have them by the weekend, or maybe early next week. Until then I can just finish polishing the software.

If you are interested, the schematic is available in black and white or color. I’ve also uploaded another file containing the Gerbers and CADsoft EAGLE files, should anyone be interested in them.

Now, to get back to normal work, and possibly update the online documentation for the project a bit later. I also should make a post about Saturday, which was a really nice day of beer brewing, friends, and beer in the evening. (Although I think a bit too much beer… or maybe too much Mt. Gay afterwards at ‘s place.)

Crystal, PIC, and voltage regulator on a laser printout of the HMLiberator
(Click for full size image.)

The first batch of board-level parts for the HMLiberator came in today. It’s enough parts for three devices, with a few extra SMT parts thrown in just in case I drop them, sneeze, whatever.

That up above there is a laser printout of the latest board layout with the electronics filling a 37mm x 25mm area. I’m going to redo the pinout of the cables to make routing of traces more efficient, but that shouldn’t affect the other areas. Also, as you can see, the part footprints are good. So, barring any manufacturing problems, it should work out great.

I took some more macro photos (true macros) of other SMT parts received today, because I thought some people reading this might be interested to see them:

· Four size 1206 SMT .33μF 25V capacitors sitting on a dime. These are Mouser part 77-VJ12Y25V334K.
· One of the .33μF size 1206 capacitors sitting on the PCB printout.
· Surface mount parts in cut tape packaging.

After talking with jerronimo for a while on IRC about it, I think I’ve got a good idea about what I’d like my next project (after the HMLiberator) to be: a Nixie clock.

I’m thinking that it’ll be:

· Controlled by a PIC.
· Time / date / etc stored in a battery-backed PCF8583 (or so).
· Four Nixie tubes.
· Time / date / whatever will be set via serial terminal. PCB will include FT232BM for easy USB connection and footprints for DB9 connector, MAX232, etc.
· Other things may be possible via serial, including displaying one’s own data. This makes the clock also an external Nixie display for computers or embedded devices.
· Colon (:) in between pairs of digits can be turned on and off.
· Again, all open-source hardware and software. Probably done in mikroBasic since I’m getting to know it fairly well.
· I’ll make a few kits available to friends at cost, likely without enclosure.
· Maybe a bootloader so new firmware can be dumped on via serial port instead of ICSP?
· Possibly a way to control color-variable LEDs for illuminating base and / or tubes.

So, yeah. That’s a ways out, but I think that’s what I’ll work on next. :)

First Draft of the HMLiberator PCB

Having some time on conference calls this morning I went ahead and began laying out the first draft of the PCB for the HMLiberator. Well, there it is. It’s small. Really small. 54mm x 25mm, in fact, and I could probably cut it down to 50mm x 25mm if I feel like it.

A 300dpi version of the schematic is available here, if you’d like to see it.

I’ll let the design stew for a few more days while I work on the software (and other thing — especially laundry) and wait for the first order of parts (enough for three boards, $20 total) to come in. After validating that the parts match their footprints, and assuming I don’t run into any huge problems with the software, I’ll order a prototype run of boards.

Oh, I also ordered one of the OPPO DV-970HD DVD players from AV Science as well. It was US$149 with $10 shipping. I wasn’t expecting to pay the shipping, but at least I know it’ll go out today, a small company is getting the business, and the forums they run helped me learn about and decide on the player and TV.