Using a P-FET (2N5460)

[gls]

Hi,

Just finished building a Little Gem, and it was FUN! Now I'm looking at the Ruby.

Couldn't find a J201 or anything in that long list of substitutes in the faq at the store (I'm not in the US). Decided to try my luck and pick up a 2N5460 (for the equivalent of USD0.50).

Get back and look at the specs on Fairchild (http://www.fairchildsemi.com/ds/2N/2N5460.pdf) and it seems the specs are pretty close to the 2N5457 (http://www.fairchildsemi.com/ds/2N/2N5457.pdf). Except that it is a P-FET instead of an N-FET. Is there any easy way to substitute this into the Ruby?

Thanks!

[Brian Marshall]

just do it upside down.... remember the drain and source are backwards, and the gate has to reference to V+ not ground..... well V+ sort of is its ground.... you get what im saying.

[gls]

Hmm...so in the Ruby circuit a P-FET Gain goes to V+, Source goes to input/1M5 and Drain goes to 47n/3k9?

[Steben]

Hi,

Just finished building a Little Gem, and it was FUN! Now I'm looking at the Ruby.

Couldn't find a J201 or anything in that long list of substitutes in the faq at the store (I'm not in the US). Decided to try my luck and pick up a 2N5460 (for the equivalent of USD0.50).

Get back and look at the specs on Fairchild (http://www.fairchildsemi.com/ds/2N/2N5460.pdf) and it seems the specs are pretty close to the 2N5457 (http://www.fairchildsemi.com/ds/2N/2N5457.pdf). Except that it is a P-FET instead of an N-FET. Is there any easy way to substitute this into the Ruby?

Thanks!

Yes, 2N5457's are the best European substitutes in all j201 designs.
between the caps of the fet buffer you should just think of swapping the power source and the ground. So drain goes to ground, source (with resistor...) goes to power, and gate goes to power with 1M5.

Don't forget that the 386 chip is back to normal! Be carefull with the connection on electrolytic caps!

[gls]

Hi, thanks for the replies. I've been having trouble posting for some reason...ok so to change from NPN to PNP we just reverse the polarity (making sure that the caps are reversed too)?

[gls]

Like so?

[OG]

"Yes, 2N5457's are the best European substitutes in all j201 designs".

Hi Steben,
why not simply use a bf 245? (easily available here, cheap, N-fet)
Regards from "Bergen"
Olivier

[Steben]

"Yes, 2N5457's are the best European substitutes in all j201 designs".

Hi Steben,
why not simply use a bf 245? (easily available here, cheap, N-fet)
Regards from "Bergen"
Olivier

I guess BF245"A"s, no? Yes it' a possibility...
Are they much cheaper than the 2N5457's? The 2N's are easily available in my shop too though. ;-)