Looking for P-channel equivalent of an IRF510 Power MOSFET

[Nigel Goodwin]

Got the heatsink on and the feedback capacitor in place. It works exactly as simulated. Max voltage, 11.05, min voltage 7.34 or something. The heatsink is too hot to leave your finger on it, but not hot enough to boil saliva ;-). I used silver thermal compound when attaching.

Is this too hot? It is possible to run two TIP42s in parallel, or do they need to be "load balanced"? I'm starting to see why a buck converter is the preferred method for DC to DC.

Yes it's possible, you just need to add an emitter resistor in each to balance the load - but how big is your heatsink?, a larger heatsink would probably do as well?.

Generally the cooler things run the more reliable they are!.

Finally, I have a 10-ohm 10W power resistor I could put in parallel around the TIP42. In this setup, it would take just over half the current load at the minimum voltage, which is going to be most of the time.

It's a common solution when the load has a fixed minimum current draw. Bear in mind the resistor will get hot as well! - you're still dissipating the same amount of heat (just spreading it around). A 10W resistor will run pretty hot with a couple of watts through it, if you run them at 10W you will probably need dark glasses to look at it! :lol:

 

[dinofx]

the higher spec TIP41 is listed as 2WF (that's only 2W in free air - no heatsink). I've never understood why they are listed completely differently?.

So, 4W with the standard aluminum heat sink sounds safe I guess.

 

[dinofx]

Does anyone know how I can request a sample 10-ohm in a TO-220 package. These things are like $6 plus shipping. It would look a lot cooler than the huge ceramic terd I got at radio shack.

For example:https://www.newark.com/product-details/text/catalog/48982.html