Category making things

Ceramic Caps

Today a received a gigantic box from Mouser containing all the parts for the RS232 to Eaton Leonard Level Shifter v2. This includes over 100 DIP ICs, 110 BC557 transistors, shunts (jumpers), tantalum capacitors, screw terminals, LEDs, 2×3 headers, RJ45 connectors, resistors, and the FETs for current reversal protection.

I also finally bought a lead bender, so that the bends in resistors will be a lot more accurate / consistent.

Assembling these 25 is going to be a chore, but will also be worthwhile. Yay!

Now, to go to Meijer and get extra foodstuffs for the weekend.

SPI Decoder Hackery

Here’s a design I just threw together for a hokey SPI decoder so I can watch what is going on internally in the Honda Music Link. It’ll read both SPI lines and turn it into RS232 data on the PC. Basically, the software on the PICs will just data out of the SPI buffer as it fills (and triggers an interrupt) then write that out the UART. Should work, I think. The only big problem will be the decoding software on the PC.

Anyone want to write up some decoding software for me? It should be easy to do… Just needs to watch a serial port (or maybe both) and decode packets as they come in. Hell, if you can write the framework for it, I can add the decodes as I figure them out.

(The point of this is to basically reverse engineer how Honda talks to CD changers.)

Here is a write-up on ordering extremely cheap PCBs from questionable Chinese PCB fabricator Gold Phoenix Printed Circuit Board Co.,Ltd.

There’s a couple projects I may use them from. I just need to edit some files and decide on a solder mask color. (I’m not designing this myself, just changing the documentation bits of the design slightly.)

There is something odd to me about ordering $50 worth of optocouplers. I’ll be receiving many, many tubes of chips soon. It seems I’ll be making 25 of the v2.0 boards, with at least four (and most likely more, if not all) of them by the end of next week.

Also, who knew that jumpers and pin headers cost so much? Well, at least for RoHS-compliant decent quality ones. <shrug> It all works out in the end, though. Also, it’s a good thing I ordered that hundred pack of antistatic bags.

Now, to finalize the PCB and order it. (I might do that tomorrow, as I can order the boards as late as 9:30am and still get the order in before the salespeople arrive.)

Also, the Clarkston Union has raised their prices. A full order of portabello gratin is now $15.

RS232 to Eaton Leonard Level Shifter v2.0 Draft
(Click image for 600dpi version…)

After finishing up the work I had to do today I began working on v2.0 of the RS232 to Eaton Leonard Level Shifter. After delivering the first batch the customer wanted some slight changes, most notably a configurable board which could either talk to itself or either end of the communications system the Eaton Leonard benders use. So, after poking with the breadboard on Friday and documenting my findings on Saturday I set to work drawing the board. It’s the same dimensions and the power and data connectors are in the same place, but everything else is different.

I had initially tried to use a resistor network to make soldering easier, but that was going to make connecting everything in such a small space very difficult, so I went back to discreet resistors.

I might change the LEDs and the resistors connected to them. (This will be determined tomorrow.) There also might be a product name change, part number change, and some of the labeling is still up in the air. Other than that, I’m pretty happy with it. Hopefully I’ll order the first run of boards by the end of the week.

I still have to finish working on the photos from the Selfridge airshow this weekend and upload them. That’ll be another night, I think.

Do any of you know where I can find 8-contact jumpers / shunts (RoHS compliant, please) for sale?

I have a block of pins with 4 jumpers on it, and they all need to be either to one side or another, and I would rather not have four separate jumpers which need to be moved.

To clarify, here’s some crappy ASCII art explaining it:

The pins:
***
***
***
***

Will have jumpers / shunts in place like this:
XX*
XX*
XX*
XX*

Or this:
*XX
*XX
*XX
*XX

I can’t find them for sale, though. They must be a somewhat special order item, I guess…

Then again, I can’t remember the last time I saw jumpers like that on a commercial PCB, either.

Nine RS232_EL v1.0 Parts, Ready for Packaging
(Click for more photos (photo gallery retired)…)

There. I’ve got the rest of the first run of RS232 to Eaton Leonard Level Shifters (RS232_EL v1.0) boards completely assembled, washed, dried, tested, and packaged. They are now sitting in a box, individually bagged, ready for me to drop them off at lunch tomorrow.

Thanks to ‘s suggestions for lead-free stuffs (tip tinner, metal shaving-like dry tip cleaner, more flux) I was able to work past the problems I was having before with lead-free solder. It’s now just as easy to do as with the lead stuff. I might actually switch to making more, if not all, of my personal projects with lead free solder, just so I don’t have to handle the stuff.

Now it’s time to relax. I’m in the mood for some beer, but I both don’t have any, have been too busy to get (or even consume) any, and it’s too late to go out and get any. (Well, not really too late, but running out at 9:17pm just to get beer and hurry home and have one is not something I prefer to do.)

Maybe I’ll go read or something. Starting tomorrow or Friday it’ll be back to having lots of work to do, outside of normal work. Oh, and laundry. And dishes. Yay!

My legs and ass are sore from sitting on a stool for the last five or six hours, but I’ve finished assembling the first batch of the RS232 to Eaton Leonard Level Shifter parts. They still have to be washed and tested, but they look good. Now to go wash the soapy rosin-based flux off my hands and go to sleep. I have a meeting in seven hours.

All parts for the assembly of 11 RS232 to Eaton Leonard Level Shifters.
(Click for huuuuge….)

Well, with the Mouser order arriving, I have all the parts for the boards. The Phoenix-branded screw terminals seem to fit the footprint I drew for them, which is a good thing. Now I just need to wait for the boards to arrive. Part of me thinks that I should have spent the extra $30 or so on overnight shipping, but I don’t really think that waiting until Wednesday (when they are slated to arrive) will be a huge deal.

I’m really anxious about it, somewhat worrying that I screwed up something else in the design and that it won’t work. <frets>

We’ll see. :)

Lead-Free test of 555 Timer and Resistor
(Click for full res…)

Today my order of lead-free solder and anti-static bags arrived. That meant that was finally able to stick the new ETO tip on my iron, get out the new sponge, and set everything up for trying out lead-free (SAC: 96.5% Tin, 3% Silver, 0.5% Copper) soldering. To get started I acquired a spool of 0.025″ Kester SAC solder with 331 (water soluable) flux.

I must say, this is quite different… First off, I had to turn the temperature up to 750°F. Then, after that, it was rather like soldering with the low-flux no-clean lead solder. The joints don’t wet as much, flux still flows but it doesn’t seem to help as much, and the resulting joints just aren’t shiny. All of this is in line with what I’d read about lead free solder, so that’s at least good.

The flux came off nicely with a toothbrush and hot tap water (my normal process, followed by a rinse in distilled water and drying with an air compressor) so I’m quite happy with that.

After reading this article from Kester (PDF) I may give an 800°F tip a try next time, but for now I’m pretty happy with how things were coming out.

A few more photos of test joints, both before and after flux removal, are available here (photo gallery retired).