Trying to burn out a 2N3055 NPN Silicon transistor: does it work? Setup test schematic and demo

[@roncaruso931]

Some You Tubers said the 2N3055 is obsolete. That is true but I still have a few and have made circuits using them in the past. I think the pulse current to the base is a maximum of several hundred milliamps. Always enjoy your videos.

[@radiofun232]

Thanks Ron. And about that pulse current to the base of a 2N3055: it needs serious tests to get to clear conclusions, especially about the maximum current/voltage that can/could be pushed in (not damaging that 2N3055, of course...).

[@Ignazio-ez8zs]

Now THAT is a breadboard!

[@charlesdorval394]

Thamks for the video! I have a couple of them and 2 pairs of complimentary parts in TO-3, There's a future power supply on the todo list :)

[@radiofun232]

You are welcome. Don't burn them out...😁

[@billharris6886]

The 2N3055 has a maximum junction temperature rating of 200 degrees Celsius. This transistor also has a copper heat spreader between the junction die and the steel case, which greatly improves the heat dissipation capability for a steel cased part. If you look at the datasheet for this part, take note of the Total Power Dissipation parameter, which uses a "perfect heatsink", that always stays at +25 degrees C, no matter how much heat is pumped into it. This parameter shows that with the perfect heatsink, the transistor will have a junction temperature of 200 degrees C when it is dissipating 115 watts. Also note in the Maximum Power Dissipation column the W/C figure. This is the transistors thermal resistance, of 0.657. This means for every watt the transistor dissipates, the junction will rise 0.657 degree Celsius. Trying to remove heat from a device involves getting the heat through several thermal resistance barriers. Here are the typical thermal resistance barriers when heat sinking a power transistor: (1) Junction to case, (2) Case to heat sink compound, (3) Heat sink compound to electrical insulator, (4) Insulator to heat sink compound, (5) Heat sink compound to heat sink, and (6) Heat sink to air. You can calculate the junction temperature in whatever project you are making, by measuring the case temperature after your heat sink has equalized in temperature (this takes about 30 minutes). Measure the case temperature, measure the transistor collector current, measure the voltage from collector to emitter to determine transistor dissipation, then multiply the wattage by 0.657, then add this figure to the case temperature, which gives the junction temperature. As an example, say your transistor is dissipating 25 watts and the case temperature measures 55 degrees Celsius. Case temp times junction-to-case thermal resistance plus case temperature = junction temperature. (25W X 0.657) + 55C = 71.4 Degrees Celsius Junction Temperature. We are well under the maximum junction temperature rating for this particular example. The cooler you keep the transistor, the longer it's lifetime will be. This example also shows that it is best to mount the heat sink on the outside of the chassis to eliminate additional thermal resistance barriers.

[@radiofun232]

Thanks for your very valuable comment. Good to know and important for everyone! 9 dec. 2024

[@bblod4896]

I've seen older analog power supplies with large iron core transformers and a regulation circuit using ten 2N3055 transistors in parallel mounted on a large heatsink. The old supplies may be heavy but they put out a clean DC source unlike today's switching supplies. Although obsolete, Digikey still has 2N3055G available for $8.25 each.

[@radiofun232]

Thanks Barry, true! In the past they used them in that way. And they surely had that clean DC out! Without any "noise" (in the broadest sense of the word....could be "everything".....🤐) on the supply leads.

[@generalingwer4341]

That's called operating a transistor out of its "safe area" of operation.collector current vs collector voltage vs junction temp....electronics is fun🙂the 3055 is a iconic trn.work horse for sure,well put.

[@radiofun232]

This mishandling is indeed out of order. You have an interesting YT channel and I have subscribed.

[@generalingwer4341]

@radiofun232 thanku.😀

[@johnwynne-qx6br]

Thumbs 👍 i suppose like a fuse there can be slight differences. Interesting test.

[@radiofun232]

Yes, John, and (say) the idea is: always mount such a fuse at the front of the device. For easy replacement. An automotive lamp of 55 Watt (12 Volt type, incandescent type) can give the circuit absolute good shortcut protection, also 2 automotive lamps of 21 Watt (12 Volt types) in series can do that job. It surely will hamper the max. output current somewhat, but for a workbench Power Supply that is no problem. Because the more important thing is this: during electronics experiments, using it as a workbench supply, always (!) shortcuts are made and, when the shortcut-time is very small, the classical transistor shortcut protection circuits often do not work. They are in general not quick enough....sorry to say. Thus even with these HQ shortcut protection circuits, the series transistor can burn out (combined with worse effects). Such a car lamp always (!) works in that situation to safeguard . NB: reverring to my earlier video's, links in the description. Thanks. 10 dec. 2024.

[@Whatmyoldname]

Good come old School 🎉

[@Dazzwidd]

I would have put it on a medium heat sink so you can really give it an extended thrashing

[@radiofun232]

Even with a small heatsink in the order of a 10 cm. x 10 cm. aluminum plate of 1 mm thick, it can take days before that 2N3055 is properly (...) destructed..Anyway: a good idea. 14 dec. 2024.

[@Dazzwidd]

@radiofun232 drill holes in a small saucepan and mount it to that. See if you can boil water 😅