Chassis Mount Power Resistor

As part of the page covering How to Dearte a MIL-PRF-39009 Resistor, a new page was added to cover mounting area. The original MIL-39009 resistor page covered power dissipation vs ambient temperature, which is what most of the Component Dearting pages cover. More specifically output power by temperature is normally How Resistors are Derated.

This new page covers Derating MIL-PRF-39009 Resistors by Mounting Area. Or available power dissipation in watts compared to the area of the chassis the resistor is mounted to. This style of resistor is designed to be mounted to a metal surface to aid in dissipating power. So this is one of the few styles of resistors that shows a dearting chart that uses something other than ambient temperature. Although the original page does provide power dissipation vs temperature, the chart covering chassis mounting area is not related ~ use one chart or the other for derating purposes.

For reference here is another chart for Dearting a Variable Wire-Wound Resistor, and another for Derating Resistor Networks. But visiting any of these page links will show all the other styles or package options used and their derating charts. Most of the pages in this section have all the same page-to-page links.

Graphic: 

MIL-PRF-39009 Chassis-Mount Power Resistor

Derating an IC

Added a page to cover Derating Integrated Circuits. I think the page only has two sentences. The new page is linked off the main Component Derating page.

As time goes on, I'll add more information. I also up-dated some of the terms on the Transistor Derating page.

The entire derating section is increasing in page views, but not by the amount of time I've been putting into them..

555 Projects

A few weeks back I added a few more pages related to the 555 timer. One circuit uses additional passive components to compensate for the tolerance of the external capacitor; 555 Timer Tolerance Compensation. The second page covers a Reducing Frequency 555 Oscillator. Both circuits are connected as Astable Multivibrator circuits.

Both pages were added to the engineering site map, but it does not appear that either page ever made it to this blog. I only noticed because both of those 555 pages have only received 2 visits in the last two months. It's almost like neither page has been index by Google? However I think the pages were only added 3 weeks ago.


For what ever reason my computer is slowing down to a crawl so I'll end this post and re-boot. Although I think the connection with the internet is going south. But I don't really want to reset the modem because a few of the open pages won't like it, including this blog as it auto saves about once a minute.

-- Ok that work, must have just been a memory leak.
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Resistor Networks

I went a head and added another page for a 20-pin Resistor Network. I added the link  to a number of pages in that section, so many of those pages got updated. A 20 pin through-hole DIP seems like a pretty big package for the termination the package offers, but I guess if you have the board space.... Seems like the BGA package added the other day would be a better alternative. But of course the resistor arrangement is different, at least for the example provided.

I don't know what the application is for because the resistors seem like odd values, but there must be some common usage otherwise they wouldn't make it.

So any way it looks to be about 17 pages in this section, at least with the page address starting with resistor-network. All together they bring in a few visitors to the site, and most of the pages have a 50% bounce rate.

Resistor Array BGA Package

A new page was just added to cover a BGA Resistor Array. The new Resistor Array is linked off the main Resistor Network page, which really covers a resistor network in a 16-pin DIP. I also added a link off the page covering Resistor Array Manufacturers, cause it seems like many of the other resistor network links are on that page.

I also added the page link to the SiteMap for the web site too.

None of these pages covering this topic are doing well. It could just be there is not a lot of search traffic for resistor network packages.

Looks like the last time I added a page to this topic was on Jan 12, as Resistor Networks. Then on Dec 3 as a DLCC Resistor Array. I've been slowly been added to this topic over the last few months.

I also up-dated the new Google search bar, if you happen to be following the other blog. The site search should work the same but the search bar looks a little different.