Transistor type not working....

[JimRayden]

I needed a bunch of J201's but the local store didn't have them. They also didn't have MPF102, but they found a replacement for it. BF245A.

Now, I breadboarded a Fetzer to test it out. The J201 works great in it, but I can't get the new one to work, no matter how hard I try. The wierdest thing is, it lets sound through even if the battery isn't connected. Plus, if I want to bias it to 4.5V, I'll have to use over 4.5V drain resistor. I DID check the pinout.

I tried quite a few of them and came to a conclusion that they can't be faulty. Do they work differently? What is this?

-----------
Jimbo

[MartyMart]

Jim I did some checking and found this :
MPF102 replacement is a BFW61
The BF245A that they gave you seems to have a replacement
called BFW56, I can't find out if thats close enough to a J201
or an MPF102 .. !
Perhaps they were wrong ? or it's close but way too little gain
compared to both the MPF102 and j201

Hope that helps some ?
Marty.

[JimRayden]

Just when you think you've checked EVERYthing and the thing isn't still working, check once more. Then you discover it was still the pinout  you were misreading. 

I feel good about it working but embarrassed for it taking so long to figure out. Just when you think that you have learnt by experience, it slams you right in the face.

---------
Jimbo

[MartyMart]

Glad you got it working, pinout will always "bite you in the ass" when you're
not looking !!!

Marty.