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RE: [N8VEM-S100:2372] Z-80 V2 question

Probably more info than you want, V regulator heat sinks have two main functions.  For negative voltage regulators they are often used to separate the back of the regulator from the (normally) ground plane of the board.

The second use is for cases where there is a +5V trace (or rarely) other  trace running “under” the heat sink which is normally grounded.  This would lead to a disastrous situation where you would have a direct short.   Now as it happens there is often sufficient varnish on these boards to act as an insulator but the risk is as the heat sink heats up and wares with use,  it will decay.   Mica heat sink insulators last forever.  Most “electronic” component shops sell them for a few cents.   Jameco has a (rip-off) TO-3 kit, see Jameco #34139,  but shop around.    So ---  board, mica insulator, heat sink, regulator.  The screws are the regulators connection to ground.   Another way is to add a standoff washer between the two screws board and hear sink. This forms an air space between the board and heat sink.  Clearly no plastic screws!






From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of Joe Herdler
Sent: Saturday, February 8, 2014 10:50 AM
To: n8vem...@googlegroups.com
Subject: [N8VEM-S100:2372] Z-80 V2 question




Here is a truly newbee question. On the Z-80 V2 board, the LM323K requires a heat sink. I have ordered said heat sink, but am not sure how to assemble the TO-3, heatsink and board. Two pin insulators came with the LM323K unit, but no mica bottom insulator. What is the mounting sequence? Heat sink, then TO-3 or TO-3 then heat sink? Do I need a mica insulator between the heat sink and TO-3, or a second one between the board and whatever is mounted first?


Sorry about such a basic question.


Thank you in advance!




Joe H

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