74244 Octal Buffer

Added a new page to show some details regarding the 74244 Octal Buffer. I was adding the page to have a link of one of the interface bus pages, but now I can't remember which interface uses the 74244 buffer. This particular buffer is a 74HCT244 which comes in a 20-pin PSOP, so a link from that page points to it too.

A link also points in from the main Functional IC Schematics page, and the individual page that covers 16-bit Buffer ICs. Like all other new pages I also added a link to the Engineering Sitemap for the Engineering Web Portal.

The link text used for the last two links are used so the search engine sees something other than a link to 'home' or 'sitemap'.

Logic True Tables

I added a new page to hold a Glue Logic Truth Table covering each of the standard logic functions. The graphic already resided on the web site but was accessed by link to a graphic stored out on Picasa. So no new data was added, just moved onto a new page to hold the graphic. So far the new page is linked from the two other pages that had already pointed to the graphic; Definition of Triac [first term on the page], and the page on Glue Logic Timing.

So the Engineering Portal gets a new page, but at the same time it should be a page that will see little if any visitors. It's a common search term with no page text so maybe it will get some internal traffic, but should not see any from a search engine.

The point was not to generate a page which will never been seen. The original graphic was a 100k bit-map file stored out on Picasa, while the new file is stored on my server and only takes up 30k bits. So my server will see a 30k hit each time the page is viewed, it was zero while the pic file was stored off-site.

It's Google's view that a file on another server requires another DNS look-up [to find it] which slows the site down, and of course the new file is 70k smaller. Google started to also rate web sites on speed in addition to all the other things Google rates a site on. So this change makes the site appear faster to Google [a computer], but a visitor would never notice.

It's also better to have a picture embedded within the site and not just use a pointer out to some other server that holds pic files. The attached graphic is a pic of an AND gate and the true table for that AND gate.

Composite Video Connection

I added a new page to cover Composite Video. The video interface was always listed on the Video Buses page, but because there were to many graphics associated with Composite Video I moved the topic to a new page. The link was also added to the Cable Buses page, Interface Buses 'C' and the list of all Interface Buses.

Except for the graphic no new information was added, this is an out of date interface. I still use it to connect to my older VHS tape decks, but I really stopped using the VHS stuff years ago.

I didn't check for any other page to page links pointing to the Composite Video topic, because the links on that page still work, or point to the new page. The attached graphic is one of the Sony Stereo AV receivers I have, I think this one is a 6.1 channel amplifier. I also have another 7.1 Sony receiver which is just about the same.

The receiver has 6 video channels using the Red/White/Yellow Composite video, including; TV/SAT, DVD, Video 1 and Video 2 and a single Yellow composite video connection for a monitor. Three channels of component video are also shown [Green/Blue/Red].

Low Profile BGA packages.

I added a new page to cover a Low-Profile Ball Grid Array or LBGA. For some of these pages I provide package dimensions, but I didn't bother this time. I'm not even sure if the exact height of an LBGA is set or if it's more of an industry standard.

A related page covers a normal Ball Grid Array. Right now the page is a changed copy of the BGA page so I still may need to make some changes. But the important thing is that I got the new page added tonight before I got side track with fixing some other page. The new page is linked off the page that covers Surface Mount IC Packages.

Although BGA style packages are not used for processors in PCs they are used for a number of other components within a PC. Pin Grid Arrays are used for PC processors, while BGA style devices are used for memory and chip sets.

However BGA devices are used to great extend in industry, not because they always have more pins than a PGA but because BGAs are surface mount devices. Normally it's preferred to have all surface mount devices or all through hole devices during board construction.

High Power Transistor Packages

Transistor packages usually use the nomenclature TO-xx, where TO stands for Transistor Outline.  There are a number of transistor packages that will handle high power or high current, but it also depends on the semiconductor inside the packages.

A number of different transistor packages have been added over the last month, several can handle higher power loads. One package style is the TO-3 flange mount body. The TO-3 style dissipates a lot of heat because of the large metal package and because the metal flange is normally mounted to an even larger metal plate to dissipate even more heat. The most common TO-3 package holds two leads, with the case acting as the third terminal. Two additional new TO-3 related pages were added; the first a 4-lead TO-3 package, and the second an 8-lead TO-3 package.

Another through hole style high power package is the TO-220, although this one has a metal tab to dissipate heat. The 3 terminal package already resided on the site; however a 5-terminal TO-220 and a 7-Lead TO-220 package were added. The 7-leaded package has staggered leads, and there's an additional 5-Staggered Terminal TO-220 package to compliment it. Either of the new packages are designed to hold more than just a single transistor or FET; operational amplifiers in the case of the TO-3 package or regulators in the case of the TO-220 packages.

The other high power transistor case is the TO-263, or the surface mount version of the TO-220. There's a 3-terminal version, a 5-Terminal TO-263 package and a 7-Terminal TO-263 package.

It's easy to determine the number of pins required for a particular package, normally the function will dictate the number of leads. However it's a bit harder to pick the correct package style. So these are a few of the transistor package styles designed to dissipate high heat on the site.