Transistor exchange?

[letimagesbefree]

Hi all,

I am attempting to build a "Soul Preacher Compressor" today. I have made the pcb and I have the components except for the transistors that they ask for.
The ask for 2n3904 but I was hoping to use 2n5098's is that OK??
Thanks for any help??

[letimagesbefree]

Actually the Transistor I have is a 2n5088

Apologies!

[kevinkr]

Take a look at the data sheets for the 2N3904 and the 2N5088 and see what matches and what doesn't. Probably the most important thing is the beta/hfe.. Note that the 2N3904 is readily and very cheaply available in a variety of packages for the off chance that the 2N5088 does not work satisfactorily. Noting that the hfe of the '88 is a great deal higher, were it me I would stick to the 3904....

http://www.fairchildsemi.com/ds/2N/2N5088.pdf

http://www.fairchildsemi.com/ds/2N/2N3904.pdf

[dchisholm]

According to the schematic at < http://www.montagar.com/~patj/soulprch.gif >, it looks like 2 of those transistors are being used as capacitor-multiplier power rail filter, and rail splitter. Those are potentially places where the higher current rating of the '3904 is required. (Just eyeballing the schematic for 10 seconds it looks like your '5088 will be OK, but a good SPICE simulation will give you a better idea of what is actually required.)

Nothing in the rest of the circuit looks especially stressful.

If the '5088's don't blow up, and don't run too hot, they're probably quite acceptable.

But, like Kevin says, since you can get '3904's for a few pennies each . . . why would you want to use your '5088's?

Dale

[letimagesbefree]

Hey thanks mate, I'll take your advice!

Can you or someone else answer me this?? Is a jrc4558 the same as a cd4558???

[letimagesbefree]

I also have been reading that a opa2228 is a much better option audiowise than a 4558
Is it possible for me to just swap out a 4558 for a opa2228?

Sorry for all the questions!!

[Stormrider]

Layout and power supply quality come into effect with some of the faster opamps like the OPA. You can run into oscillation and noise problems if everything is up to snuff.

For an effects unit I'd probably just use the 4580, TL072 (jfet), or a regular NE5532. No reason to use an expensive OPA for these types of circuits.