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-   -   is this really a TO-5 insulator? (http://www.diyaudio.com/forums/chip-amps/17360-really-5-insulator.html)

travis 6th July 2003 01:58 AM

is this really a TO-5 insulator?
 
http://www.daggerkill.com/images/insulator.jpg

the package says it is. LM1875 is TO-5, no? what's going on? i don't see how this is going to isolate the chip from the heatsink. sorry there's nothing in the picture for scale. i had to use the scanner. camera is with sister. the pad about 1 cm across.

li_gangyi 6th July 2003 02:32 AM

ermz I think this is used for the metal can type of transistors...you place the stuff on a PCB or small heatsink (which is rarely needed) and than the transistor OVER it...meaning only the 3 legs protude out from the rubber insulator...then you solder it in place...

AudioFreak 6th July 2003 02:47 AM

Yes that is a TO-5 insulator but no it is not the correct size insulator for LM1875. IIRC, TO-5 is a small round metal can package used for some transistors etc.

theChris 6th July 2003 03:04 AM

the lm1875 uses a pentawatt (sp?) case which looks similar to a to220 case, but with 5 staggard leads instead of 3 straight leads.

li_gangyi 6th July 2003 03:05 AM

You should try finding a rectangular mica or silicon based insulator...its about the size of the chip you are trying to isolate...slightly bigger in fact...

travis 6th July 2003 04:39 AM

oops, its 220, not 5. i swear that the 1875 pdf said TO-5 the first time i was looking at it.

li_gangyi 6th July 2003 05:38 AM

yeah..people make silly mistakes like this sometimes...you can get cheapo insulators if you look into broken or spoilt PC PSUs...they have some...just smear your own thermal grease...dun use artic silver~!

AJT 6th July 2003 06:07 AM

if i am right, that is a spacer, to give some clearance for the to5 sitting on the pcb...

li_gangyi 6th July 2003 08:06 AM

yeah...it's a spacer...sometimes it's used to insulate it from the ground plane in a double sided PCB...

AudioFreak 6th July 2003 10:57 AM

Quote:

Originally posted by travis
oops, its 220, not 5. i swear that the 1875 pdf said TO-5 the first time i was looking at it.

I think the datasheet calls the package something like TO-220-5, at any rate, whatever they call it, just bear in mind that they are somewhat larger than a standard TO-220 package so insulators meant for normal TO-220 will be of no use.


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