PStwo + car

[cambre]

I'm trying to put a PStwo (slim ps2) in the car and I would like to avoid the use of an inverter if possible. The PStwo uses an external power supply that provide 8.5V and around 5.3A. I have a few questions as to the feasibility of using linear regulators or something similar to acheive this instead of going the inverter route.

This guy uses a LM138. From what I remember, LM138/338s are good for around 5A. Will there be a problem with the PStwo drawing a little more? Also, if my math is correct, the regulator will need to take care of ~5V. At 5A, this would be 25W of heat? Will a heatsink like this be sufficient or would active cooling be necessary?

Or, would something like this with a LM317 or something instead of the 78XX be better?

If nothing else, this would probably work and for the price, it may not be worth the hassle. Thanks for the help.

 

[Mohonri]

For $12.90, that third option seems pretty hard to pass up. It sounds like it's a switching regulator (from the 4A in, 5A out), which means it'll be pretty efficient, so less heat to worry about. Between the cost of parts and all the time you'd have to invest, making your own doesn't sound economical. The parts list from the first link would be close to $20 by itself.

The heatsink you linked would not be anywhere close to enough, even for the ~17.5W you'd be dissipating.

The second solution you linked would work just as well--it just requires more parts, but at a potentially lower cost: Instead of a big, expensive regulator, you have a cheaper power transistor and a very cheap regulator (cheap in cost, not quality).

 

[tex1138]

If you decide to roll your own, you should check out this datasheet from Linear which has some really good information on the characteristics of automotive electrical systems (page 12). It's also something to think about before you decide to trust your shiny new PS2 to a third-party power converter of unknown quality.

BTW, if you do decide to go with the commercially-manufactured unit, feel free to cut it open and take pictures to show us

 

[t_andrews]

I agree that that third option is pretty tempting due to the price and the fact that it was specifically designed with the PS2 in mind.

That datasheet from Linear was pretty funny at page 12, I didn't realize that the writer could get away with that. There is some good information on what can go wrong with a car supply, I just built a small (1W) stereo amplifier using two LM386s and am still a little worried that I did not put any protection in the power side (besides a on/off switch).