How do you mount your transistors ?

[okapi]

Hi peter, is there another thread where you discuss the amp in your photograph?

Tim

 

[Peter Daniel]

It was here: http://www.diyaudio.com/forums/showthread.php?s=&threadid=5399&highlight=

 

[megajocke]

Look at this, it thoroughly explains most things you would want to know about power transistor mounting:

"Mounting Considerations For Power Transistors"
https://www.onsemi.com/pub/Collateral/AN1040-D.PDF

 

[billybob66]

Re: Screw & Nuts

HPotter,

Where do you get your hardwares normally? I have so much frustration trying to get some screws and nuts in Toronto. I tried home depot, canadian tire, sayal, active surplus etc.. either they have the screw but out of stock with the nuts or washers. Or they do not have the right length. To make the amp look really ugly I managed to use all mix and incorrect subsituted mix bag of screws and nuts, some are pan head some are flat head, some are brass, square, cross, even wood screw had to do too sometimes. Not happy at all.

Chris

I've had the same problem procuring fasteners of the correct size/type. Electro Sonic carries 4-40 screws and the associated washers and nuts. Also, try hobby stores that sell parts for RC. Atlas Supply on Queen St. has quite an assortment of screws (they sell by the pound, 2.50, I think, instead of the "8 pack for 3 bucks scenario", as in the hardware stores.)

Likewise, I've had the same problem with board connectors. The PCB for my amp project doesn't have correct spacing for eurostyle terminal blocks. In some cases, I've used Keystone push-in terminals (Electro Sonic) Problem is, they're not quite "push-in", and I had to use a small needle file to whittle down the tapered pin. Not exactly the most elegant solution, but the only one I've found, other than soldering wires directly to the board.

 

[PH104]

originally posted by megajocke
Look at this, it thoroughly explains most things you would want to know about power transistor mounting:

"Mounting Considerations For Power Transistors"

Thanks megajocke. That's an excellent reference. I have an old copy from Motorola and glad to get a new clean electronic version.

Like Peter, I also like BeO insulators for special projects. Otherwise mica and grease or Silpads.

 

[billybob66]

Re: soldering TO-3

Hello Folks,

Is there any good advice to solder the two pins of a TO-3 transistor. My problem is such that the heatsink is so thick that the end of the pins are almost flush with the other side of the heat sink therefore I think I have to solder the wires to the pins prior to mounting it to the heat sink. So the wire has to feed through the holes before I can solder the wire to the PCB. It seems the procedure is wrong some how. Also, as I understand it that I should use the thickest wire that I can get away with, so I am using AWG#14 which is twice as thick as the pins, how do you solder the hard pin and hard wire together without end up with drilling the holes too big on the heatsink and secure so that it will not short to the heat sink metal?

Sorry for such a long wind question. I guess you guys would know my concern.

Thanks....

I would suggest using a TO-3 mounting socket, Chris. They're cheap, easily obtained, and you can solder wires to them, without the risks involved in trying to solder directly to the trans. Simply solder your (short?) wires to them, and insert thru the mounting holes. Remember to buy insulating bushings as well, as the body of the trans must not contact the heatsink!

 

[billybob66]

I used to solder them as well and it worked fine: http://www.diyaudio.com/forums/attachment.php?s=&postid=52954&stamp=1029963165

Man, you are a maniac! Those pics of your work(s) are a DIY wet dream, Peter. The rest of us can only turn Gumby-green with envy!