Hey all

I have two swap questions:

1. can I swap a PN200 with a BC640 PNP transistor? Is it possible to swap these two or any other suggestions to an alternative swap?

2. Can I swap a LM741 with a TL071CP? Any other suggestions to an alternative swap?

Thanks in advance!

/Jacob

 

Hmm could I use a LM393N comparator instead of the LM741 or the other way around maybe, so I dont need to have both a LM393N and a LM741 (or TL071CP).

 

The BC640 datasheet shows lower minimum current gains than for the PN200, so it may not be a good replacement.
http://www12.fairchildsemi.com/ds/BC/BC640.pdf
http://www.fairchildsemi.com/ds/PN/PN200A.pdf

The TL071 is probably better than the 741 in most respects. Check the details for yourself:
http://www.national.com/ds/LM/LM741.pdf
http://focus.ti.com/lit/ds/symlink/tl071.pdf

You may be able to use an op-amp as a comparator in some situations, but note that op-amps do not usually have open-collector outputs.

Comparators can't normally be used to replace op-amps - apart from the open-collector output they are not designed for use as stable negative feedback amplifiers.

 

Would this BC557 be a better substitute for the PN200?

http://www.nxp.com/documents/data_sheet/BC556_557.pdf

I can see that it has close to the same current gain as the PN200. But is that the only factor to consider?

 

Would this BC557 be a better substitute for the PN200?

http://www.nxp.com/documents/data_sheet/BC556_557.pdf

I can see that it has close to the same current gain as the PN200. But is that the only factor to consider?

The BC557 seems to have a significantly lower ft, 100MHz compared to 250MHz for the PN200, which might or might not be a problem depending what you want the transistor for. There may of course be other differences - look at the datasheets for yourself.

I don't know what your application requires, so it's not clear what would be critical. Finding completely equivalent devices can be difficult, so it may help to know what parameters may be most important for a given circuit.