# Weird Question 1: Transformer Heat



## Hammerhands (Dec 19, 2016)

How hot does a 100W transformer get?

If it was in a small box?


----------



## greco (Jul 15, 2007)

I'm going to bet that it is a very complicated question to answer.

It might depend on the load on the transformer, the electronic efficiency of the transformer, the materials the transformer was made form, the typical ambient temperature(s) around the transformer, the size of the box (enclosure) and the air flow/ventilation within the enclosure. 

It is extremely likely that I don't know enough to include possibly several other important factors ...including the present cost of Corn Flakes in Borneo.

*What is the application? (someone is bound to ask this)*

I await the responses from out many electronics gurus.

Interesting thread...if, like me, watching paint dry is exciting stuff.


----------



## zdogma (Mar 21, 2006)

Modern amps with good ventilation get a bit warm, some of those old Fenders (like the Showman) the chassis can get too hot to touch. Not sure how much of the heat is from transformer vs tubes etc


----------



## cboutilier (Jan 12, 2016)

zdogma said:


> Modern amps with good ventilation get a bit warm, some of those old Fenders (like the Showman) the chassis can get too hot to touch. Not sure how much of the heat is from transformer vs tubes etc


My Twin and Super both get fooking hot


----------



## greco (Jul 15, 2007)

cboutilier said:


> My Twin and Super both get fooking hot


We now have the subjective answer covered.


----------



## Hammerhands (Dec 19, 2016)

The exact application is, I’m going to make something like the Weber Z-Matcher, but lookimg more like the Box of Matches with no line-out. The box I bought for it is about the same size, the transformer has much more power. 

BM30 construction guide

1454F

Although I’m probably only going to use it with 50W amps and quietly, I should make it work as best as I can.

The exact transformer is a Weber WZC100. It’s an autotransformer, which are very efficient.

WZC-100 Transformer

I have the 100W Weber Z-Matcher that uses this transformer. It comes in a chassis that isn’t too much larger. It is ventilated, a bit, but I expect that may just be the way the chassis comes.

Z-Matcher 100w Impedance Matcher


----------



## Hammerhands (Dec 19, 2016)

I haven’t used the Z-Matcher very much, time for an experiment.


----------



## cboutilier (Jan 12, 2016)

My 50W Z-Matcher makes precisely zero heat. The case doesn't even get warm.


----------



## jb welder (Sep 14, 2010)

cboutilier said:


> My 50W Z-Matcher makes precisely zero heat. The case doesn't even get warm.


This should be how it goes. If the transformer is just used to match, the load should still be where the heat is at.
You still need a load when using the line out, correct?


----------



## cboutilier (Jan 12, 2016)

jb welder said:


> This should be how it goes. If the transformer is just used to match, the load should still be where the heat is at.
> You still need a load when using the line out, correct?


I believe so. I've never used it.


----------



## tomee2 (Feb 27, 2017)

If you know the primary and secondary resistances and the current draw and current supplied, you can calculate the power dissipated in the transformer as P=I×IxR
The temperature it gets to depends on heat transfer. If it's totally sealed off it can get very hot even with a little power. 
For example the rear brake lights in my old Chev van were like 6 watt bulbs yet they melted the housing because there was no airflow to them. 

Or, plug it in and see...


----------



## Hammerhands (Dec 19, 2016)

jb welder said:


> You still need a load when using the line out, correct?


In the Z-Matcher, the line-out is independent of the matching transformer.

[The wires go from the input to the pot with the resistor, to the unbalanced output jack then to the little transformer and then the balanced output XLR. I’m not going to put that in.]


----------



## jb welder (Sep 14, 2010)

Yes, the unit still needs a load attached at all times. So it should not soak up any appreciable power and run fairly cool. The heat gets dissipated in the load, not the matcher.
I just wanted to make sure it could not also function as an load emulator or attenuator. That would make heat.


----------

