Choosing a transistor

[The Master]

Usually when i have the need for transistors i also have the need to dot them around the PCB so they can be squeezed into small areas. Having an array of them in a DIL package may be smaller in all but it cant be split up to fit into the little spaces i have spare. As it happens ive redesigned this circuit and all the transistors are in a line but i do only need 4 of them.

Normally a TO220 package wouldnt be a problem especially if i need a lot of current but this time i only need 200mA and i dont have the vertical space for them. There will be 2 PCBs that are only 10mm apart. One of the voltage regulators will be soldered to the underside of the PCB and both of them will be folded over to be parallel with the PCB.

There will be a bigger version of this light with more LEDs but for this one im limited with space. Ive redesigned the circuit to use 4 of those transistors Luciano recommended and they all fit on fine

[The Master]

I just noticed something. Do you mean MPSA14 or MPSA13? The datasheet you posted is for MPSA13 and thats what ive been reading. The order code you posted is for MPSA14 though. In the datasheet for the MPSA14 it says Ic is 1.2A. The datasheet ive been looking at says that Ic means collector current and that one is only 500mA. Both look suitable to me except the MPSA13 is a little cheaper.

[Luciano]

The datasheet you posted is for MPSA13 and thats what ive been reading.
The order code you posted is for MPSA14 though.

Hi,

The datasheet I have posted is the datasheet of the MPSA13 and the MPSA14.
http://www.rapidonline.com/netalogue/specs/81-0142.pdf

The first page of the datasheet is added by Rapid. If you scroll to page 2
you will see the real page 1 of the datasheet and on the top right corner
you can read MPSA13 and MPSA14.

The collector current for the MPSA13 and the MPSA14 is 500mA.
The difference is the current gain.

Time to build a prototype, try both transistors.

Best regards,

Luciano

[The Master]

Im not sure which link im looking at then. The one i got using the order code from your schematic looks completely different. It has chinese in it. http://www.rapidonline.com/netalogue/specs/47-5512.pdf. Thats the one i got the 1.2A from. I guess getting both cant hurt because the bigger versions of these lights will have more LEDs so i guess its worth testing both

[Luciano]

Hi,

Will be the transitor better than the baby milk?

Best regards,

Luciano

[The Master]

Whats that mean?

[Luciano]

Bitter taste over China baby milk
http://news.bbc.co.uk/2/hi/asia-pacific/7620812.stm

[skimask]

It has chinese in it.

Are you sure that's chinese? Or is it a manufacturer's logo?

[The Master]

Im not sure exactly. It could be japanese kanji. The datasheet Luciano linked to didnt have any of that. It says its for both but the second one has a completely different datasheet. Now the datasheets from www.fairchildsemi.com are completely different to both of them :O

[Luciano]

Hi,

If the quality of the datasheet reflects the quality of the product....
http://www.rapidonline.com/netalogue/specs/47-5512.pdf

Compare the above datasheet with the datasheet of the MPSA14 made by Philips Semiconductors.
http://www.nxp.com/acrobat_download/...s/MPSA14_7.pdf

* * *

Make sure you know who are the makers of the components you use.

Best regards,

Luciano