Bob Cordell Interview: BJT vs. MOSFET

anatech said:

I really ought to order some bulk to pass down to my children. Maybe some belleville washers while I'm at it.

-Chris


Look up a company called Small Parts Inc. and get on there mailing list. Facinating assortment of hardware, metals, plastics, tools, glues, etc.; including metric, and their stock includes the tiny end of the spectrum as well.

Great for anyone who prototypes mechanical stuff. I order from them regularly and they are and excellent company to deal with. The reason to get the catalog is that there website is a bit of a challenge.

Highly recommended.
 
anatech said:
Hi Bob,
Convert it to a jpg or something (the box has a list of file types). Either that or host the file on a server and link to it. This might be better.

You could also "zip it" and attach the file.

-Chris


Hi Chris,

Thanks. I know I'm a dufus when it comes to computers. I made it into a JPEG and tried to post it, and it still seems not to have worked, as it did not show up when I previewed the post. I must be missing something obvious here. After I put in the text, I go to the box below for attaching a file, just browse to the file and then double click on it. The file path shows in the adjacent window. But when I then preview the post, there is nothing there but the text. This is just what happened when I tried to post the png version. I must be missing a step.

Thanks,
Bob
 
Hi Bob,
I must be missing a step.
Don't worry, this caused me some trouble early on as well.

I'll bet the file is too large. There is a size limit of 100 KB I think. Try right clicking it and choose "resize pictures", if you are not running XP, I don't know. If the original file size is less than 100 KB, then just change the suffix and tell us when you post it.

-Chris
 
Hmmm.........have a look at the 10V-Vce fT vs IC for these devices............


http://www.onsemi.com/pub/Collateral/MJE15028-D.PDF

I will redesign my low-V rail tracking 16A-Iq class-A core with 25 parallel pairs of these instead. 16A Iq/25 = 0.64A. That will put my average class A operating right near the fT peak – 85MHz for the PNP devices and about 70MHz for the NPN’s!
And the low-Ic fT droop is heaps less severe too!

These “driver” transistors are rather cheap and would be great for a conventional low power (<100W) design. They have low Cob and Cib, so you can parallel heaps of devices for SOA headroom without disadvantage.

Cheers,
Glen
 
G.Kleinschmidt said:
These “driver” transistors are rather cheap and would be great for a conventional low power (<100W) design.

My thoughts exactly for the 250V MJE15032/33 devices when the hurd was still getting them en masse as 25-rail samples from On.(Ft data is not on the sheet, but can be found on diyA with a search)

Example from overhere, with 64 SMT 120MHz ringemitter devices per channel, 32/ch. for the stereo model.
www.arrayaudio.nl/abssnd.html
(trust me, i nagged the head of the vdh coilwinder too)
 

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Hi Bob,
when you preview your posting the Forum software automatically removes the attachment from the dialogue box.
You have to re-insert after each preview.

If it's the wrong type or too big or more than 1000pixels (even way under 100k limit) the reply tells you.
 
AndrewT said:
Hi Bob,
when you preview your posting the Forum software automatically removes the attachment from the dialogue box.
You have to re-insert after each preview.

If it's the wrong type or too big or more than 1000pixels (even way under 100k limit) the reply tells you.


Hi Andrew,

Thanks. Does this mean that I will never see the attachment when I preview the post? Or does it mean that I should see it in the preview, but that I have to just re-attach it before I submit?

I have never seen evidence of the attachment in the preview, even when I tried last night to just attach a zip file.

Thanks,
Bob
 
anatech said:
Hi Pooge,

The power is in your hands to make this idea come to life. Simply wish it and follow the steps to start a new thread.

I think there is value in your idea. Please, cast the first stone!

-Chris 😉


I have started a new thread about biasing/temperature compensation of Thermal Traks here:

Moderator, please move Bob's related posts to the new thread.