Yup, seriously. I hate not finding it before. This guy has so many "uncommon" things I love. megaAVR-0 uC, Linear Regulators and its internal implementation, etc. FesZ Electronics is very good too. They should make a few videos together.
Im upgrading to a heat sink with a new SSR i had to replace in an infrared conveyor belt dryer. The new dryers come with heat sinks, mine failed after 19 years so i dont think i need the heat sink but after your video i realize a 50A 3-35vdc input and 24-280vac output probably needs it. Thank you
Picking the best mosfet when we get quotes for insurance we go to comparison sites, it would be handy to have one comparing specs of components save trolling through loads of data sheets.
It is very nice explanation on all calculation and useful. do you have a template to do all calculations by inputs all necessary parameters? I like to get a copy if possible
This is truly a clear-cut video on this subject, and I love it. However, in my situation, I seem to have run into a bit of a snag with the equation. I'm using a high-power BJT that allows a maximum current of 30 amps. In my circuit, I've measured that it absorbs about 91 watts of power (I've rounded up to 100), and the datasheet shows a maximum operating temperature of 150C. Rjc is 0.5, and I follow your rule-of-thumb value of 1.6 for Rcs. When I plug these numbers into the equation, and attempt to solve for Rsa, the value is negative. Does this just mean that there is no heat sink, on the market, that could ever be used to cool this transistor at 100 watts? Or, perhaps, does this equation only pertain to a certain range of power components? The datasheet, for the transistor, claims that it has a total power dissipation of 250 watts. This is in the "maximum ratings" section. Because I'm only considering a usage of 100 watts, shouldn't I be able to keep it cool with a heat sink? I agree, with many others, that you, easily, have the best video on this topic. Keep up the great work!
If the equation yields a negative number for Rsa, then it's physically impossible to pick a heatsink that keeps the transistor within the temperature rating. At this point the only way to solve the problem would be to choose another transistor with a lower Rjc value, lower your ambient temperature, lower your power dissipation, or raise your maximum temperature. It might help to know what exactly the transistor will be doing. 91 watts is A LOT of power. This could potentially be OK if the load is pulsed and isn't continuous since there wouldn't be enough time to heat the transistor up. Depending on what you had in mind, some sort of switching solution may be more appropriate.
I wasn't going to tell you that your calculations need work, but.. At least what about the 5 Watts the regulator drives to the load? So your 7 Watts is actually 12 Watts plus.
The entire system has 12 watts. The regulator drops the 12 volt input down to 5 volts, resulting in a 7 volt drop. In order to lose those 7 volts, the regulator dissipates it in the form of heat. In this case there is 1 amp so 7 watts. The load itself has to deal with those extra 5 watts, because it is the one with 5v on its input.
@@SineLab Yes, so your power supply will see 12 Watts and the total dissipation on the 317 is also 12 Watts of heat on it. The transistor inside the 317 does get hot with the output load not just from collector to emitter voltage.
Just don't stop! THANK YOU!
Very underrated Channel
Thank you!
Yup, seriously. I hate not finding it before. This guy has so many "uncommon" things I love. megaAVR-0 uC, Linear Regulators and its internal implementation, etc.
FesZ Electronics is very good too.
They should make a few videos together.
Im upgrading to a heat sink with a new SSR i had to replace in an infrared conveyor belt dryer. The new dryers come with heat sinks, mine failed after 19 years so i dont think i need the heat sink but after your video i realize a 50A 3-35vdc input and 24-280vac output probably needs it.
Thank you
Picking the best mosfet when we get quotes for insurance we go to comparison sites, it would be handy to have one comparing specs of components save trolling through loads of data sheets.
Best video thus far on this topic!
I'm glad that you were able to find it helpful! :)
Excellent info. Very helpful, thank you!
It is very nice explanation on all calculation and useful. do you have a template to do all calculations by inputs all necessary parameters? I like to get a copy if possible
This is truly a clear-cut video on this subject, and I love it. However, in my situation, I seem to have run into a bit of a snag with the equation.
I'm using a high-power BJT that allows a maximum current of 30 amps. In my circuit, I've measured that it absorbs about 91 watts of power (I've rounded up to 100), and the datasheet shows a maximum operating temperature of 150C. Rjc is 0.5, and I follow your rule-of-thumb value of 1.6 for Rcs. When I plug these numbers into the equation, and attempt to solve for Rsa, the value is negative. Does this just mean that there is no heat sink, on the market, that could ever be used to cool this transistor at 100 watts? Or, perhaps, does this equation only pertain to a certain range of power components?
The datasheet, for the transistor, claims that it has a total power dissipation of 250 watts. This is in the "maximum ratings" section. Because I'm only considering a usage of 100 watts, shouldn't I be able to keep it cool with a heat sink?
I agree, with many others, that you, easily, have the best video on this topic. Keep up the great work!
If the equation yields a negative number for Rsa, then it's physically impossible to pick a heatsink that keeps the transistor within the temperature rating. At this point the only way to solve the problem would be to choose another transistor with a lower Rjc value, lower your ambient temperature, lower your power dissipation, or raise your maximum temperature.
It might help to know what exactly the transistor will be doing. 91 watts is A LOT of power. This could potentially be OK if the load is pulsed and isn't continuous since there wouldn't be enough time to heat the transistor up. Depending on what you had in mind, some sort of switching solution may be more appropriate.
Nder if a form of a heat sink could be used for siding on a house to reduce heat.
Great stuff! Thanks so much
Glad it was helpful!
This issue has cost Sony and Microsoft millions. It's cool to see the calculations but the real world is messy.
Heat sinks are tricky to get exactly right. :)
Where's the TO-3 example!?
Where did you obtain the TO-3 heatsink?
From DigiKey
Very good video! I subsribed to you
Thank you very much!
Tekrar seyret
Cute video but you screwed up the mounting of the To-3 transistor. Not too good. I have seen worse though.
I wasn't going to tell you that your calculations need work, but.. At least what about the 5 Watts the regulator drives to the load? So your 7 Watts is actually 12 Watts plus.
The entire system has 12 watts. The regulator drops the 12 volt input down to 5 volts, resulting in a 7 volt drop. In order to lose those 7 volts, the regulator dissipates it in the form of heat. In this case there is 1 amp so 7 watts. The load itself has to deal with those extra 5 watts, because it is the one with 5v on its input.
@@SineLab Yes, so your power supply will see 12 Watts and the total dissipation on the 317 is also 12 Watts of heat on it. The transistor inside the 317 does get hot with the output load not just from collector to emitter voltage.
P = I * V
@@davestech6357 so what you're saying is that the load dissipates no power at all?
@@anonymouseniller6688 yes *the load will* away from the lm713.
All the music does is distract from the information you are presenting. just because you can add music doesn't always mean it's a good idea
It's interesting how he doesn't give hearts to the negative comments. It's like he doesn't want to test and improve.