oneTesla

I added a thermometer to the heatsink.
It must be useful for safe running.

Nice addition, but you might want to put the thermal sensor closer to the IGBTs. If there is a sudden rise in the temperature of the IGBTs, it takes a while for that heat to transfer all the way to the top of the sink. Also, the temperature is significantly lower at the top of the heat sink than at the bottom. Your temperature sensor is still useful to keep an eye out for problems, but it will show a lower temperature than the actual IGBT temerature, and it will also show a rather slowly changing average over the past few seconds. Therefore, you may not notice in time if the bridge suddenly starts to run too hot.

Hello stegu. Thank you to your comment.

stegu wrote:you might want to put the thermal sensor closer to the IGBTs.

Sure.

The place I fixed the sensor was selected by the reason that it was easy, without detatching the heatsink from the board.
If my IGBTs would blow again, I am going to fix the sensor nearer to the IGBTs.

Blue gives it a little kick.

What components are you guys using? I found a temp display on DigiKey but it was $48.

viewtopic.php?f=16&t=858&start=10

8 dollars US on ebay.

Has the thermometer shown any drastic temperature increase of the heatsink?

Yes. See link below.
viewtopic.php?f=16&t=858&start=10#p2138

I usually run at full power. If the temp gets above 120F I drop the power down slightly and the temp drops within seconds.

So I got two of those thermometers. I just got them installed, and got my coil running again after blowing out my transistors on the Final Fantasy fight theme song. I put one sensor on the heat sink near the IGBTs, and the other at the primary coil. In the past it seems like if my primary saw a +10F change over the ambient temp. then catastrophe would strike. I'd like to build in some more protections since my coil still seems very fragile, and I'm really getting tired of buying new IGBTs.

Hey gang!

So for those who have done this, what temp do you look for? East Texas said 120F, which would be about 48C. I bought a thermometer rated up to 70C thinking that would be fine. I've got the sensor right between the two IGBTs, and even on lowest power it almost always hits 45C in the course of one song. If I turn it up louder, it'll easily get up to 80 within a minute or two without any damage.

I've been using the coil for a while now, and have never had a problem running at higher levels for entire songs as long as I give it a break in between songs, so I'm thinking 120F is definitely too conservative for my setup.

What temp have others noticed the IGBTs will actually go at? I checked the spec sheet for them online and it says they're rated up to 175C!!! I think that's an internal temp though, so what I'd read from the probe near them would be lower than that. But, I don't know by how much. I'm thinking about ordering another thermo that will give me a better idea of their temp, but after 110C it looks like they all have larger metal probes, and I'm not sure that would work as easily as the smaller wire ones. Does anyone else have one hooked up this way? Is 110C a reasonable top end or should I go for the 125 and just wrap the probe in electrical tape or something? I don't see any of the little ones that go higher that.

Or, I could just move the probe further from the IGBTs, or move it up to the primary coil. It sounds like others measure it that way, but I would ideally like to know the actual temp of the IGBTs since those are the parts that fail first.

Thanks for any advice!