MUR860 Qs for P.Daniel, BrianGT

[D_GR8_1]

Hi Peter, Brian,

looking at the nigc_kit-users_guide.pdf document, I see that your rectifier boards are assembled without any heatsinks on the diodes (MUR860s).

From another one of my posts, Per-Anders states that anything higher than 3A through the MURs would require a heatsink!?

My Regulated PSU will use a LM338 regulator which is a 5A regulator. So the max through the diodes I would expect would be 5A.

Do I need a heatsink? And why arent you guys using them?

[hifi]

Peranders probobly ment that anything above 3A, continious needs heatsinking your regulator will not constitue a continious load so you will be okay.

/ micke

[peranders]

Exactly Start play music and if the rectifier gets hotter then h**l, then you need a heatsink... which I don't think you do.

Your MUR860 can take 8-10 A with good cooling and transientwise much more.

If you look around, how many Gainclones with heatsinks on thier rectifier bridges have you seen? Correctly, none.

[D_GR8_1]

Well Per-Anders dude, you are confusing me. This is what you said initially:

Location: Göteborg, Sweden Post #43 quote: Originally posted by D_GR8_1 I was told in another post that the MUR860s dont need to be placed on heatsinks!!! Heatsink is needed if you run more than 2-3 A through the diodes. 1 A => 0.7W 2 A => 1.7 W 3 A => 3 W Approximate values.

Now you say that I dont need heatsinks. I am designing a PCB, so if I dont need a heatsink I will cluster the diodes much closer together, if I need heatsinks the layout needs to be quite different.

So, which is it?

I dont have the luxury to see whether they need heatsinks or not as that will mean another PCB design!

[pinkmouse]

In normal use, at reasonable levels, the current flowing is is lower than 3A. If you were using the amp for long periods at high levels, then it makes sense to add heatsinks.

Why don't you just design a pcb with room for heatsinks, then you can add them later if required.

[Peter Daniel]

Sometimes the diodes get pretty warm, but they don't need heatsinks (when you run 2 channels only).