Having fried (i think) a component on my megasquirt, where is a good place to get spare components from? went into maplins today and was unconvinced by their staff that i'd get the right bits!

I want to re-do the fuel pump circuit so i Need a Q2 Transistor (NPN45V 1000mA to-92)
a Q19 Transistor (NPN SSGP 200mA to-92)
a D4 Diode (22V 1W 5% DO-4)

Can someone in the know let me know if these are the same.....

Q2 Tranny BC635

Q19 - Tranny BC549C

D4 Diode (Zener) BZX79C 22V

Cheers

Ash.

rs, farnell, cpc all sell what you need.

Q2 should be a Zetex ZTX450, the BC635 is a reasonable match, though hfe (gain) is a little bit lower. Shouldn't matter as it's used as a saturated switch so should be plenty of base current to switch it on. Watch out of the polarity though, they are slightly different packages and the collector and emitter are swapped on the BC635 compared to the ZTX450 (the two outside pins, the middle one is the base which is the same on both).

Q19 should be a 2N3904. This is a very, very common transistor, even Maplin sells it under code QR40T.

The Zener diode D4 should be a 1 watt part, the one you have linked to is a 1/2 watt part and is not really up to the job. Maplin sell the BZV85C which is a suitable replacement, part code N47BZ.

HTH.

[Edited on 8/9/09 by MikeRJ]

I just got Phil from extra EFI to post me the bits, arrived next day excellent service.


Regards Mark