how to start with power transistors?

[001]

how to start with power transistors?
voltage and surrent sources, darlingtons etc
thanx

[Zero999]

how to start with power transistors?
voltage and surrent sources, darlingtons etc
thanx

Be more specific.

What project are to trying to build?

A power transistor needs to have a good enough heatsink to avoid overheating. The key to thermal design is understanding the thermal resistance specified in ^oC/W, i.e. a heatsink with a thermal resistance of 1^oC/W, will raise its temperature by 1^oC above ambient, for every Watt of power produced by the power device attached to it. Transistors also have a thermal resistance specified between the junction and case, which works on the same principle and the same goes for thermal pads. The thermal resistances of the heatsink, transistor's junction to case and thermal pad all add together. For example, if a transistor has 10V across it, the current is 1A, the power dissipation will be 10W. If it has a maximum junction temperature rating of 120^oC and the maximum temperature of the environment, where the circuit will work is 40^oC, then the maximum permittable temperature rise is 120-40 = 80^oC. The maximum thermal resistance between the transistor's junction and ambient is 80/10 = 8^oC/W. If the transistor has a thermal resistance of 3^oC/W between the junction and case, the maximum permissible thermal resistance of the heatsink and thermal pad is 8-3 = 5^oC/W.

Another issue is the device's safe operating area, which greatly reduces the device's maximum power rating, at higher voltages, especially with BJTs.
https://en.wikipedia.org/wiki/Safe_operating_area

[001]

Yea
Thanx

Where I can read some tutorial specially for power electronix?

[Sceadwian]

Your question is too vague, Hero999's general suggestion to learn how to interpret thermal considerations is probably the most important thing to learn. You're going to have to be more specific then that as all the consideration of general electronics apply to power electronics.

There are device and application specific problems that could occur such as DV/DT latching of power Mosfets as one example. It depends too heavily on your specific usage.

https://www.ixys.com/Documents/AppNotes/IXAN0061.pdf

[Zero999]

Yea
Thanx

Where I can read some tutorial specially for power electronix?

Far too vague. What aspects of power electronics are you talking about?

My previous post dealt with thermal design, especially of a linear device, because it's where most newcomers start. A switching element is a bit more complex, especially if it's working at a high frequency, where the switching losses will be significant.

[xavier60]

how to start with power transistors?
voltage and surrent sources, darlingtons etc
thanx

Do you want to do some experiments? You could start with a simple zenner and series pass transistor regulator
Do you have a safe unregulated power source?

[xavier60]

 Rs can then be replaced with a constant current source to improve the performance.

[GeoffreyF]

I would suggest that you start with low power ones.  The principles are all the same.  All the types of circuits you mentioned can be explored with low voltages and currents.  The costs of projects, of mistakes are less.  If you are exploring higher power, there are also more issues with heat dissipation and even with fire.