I am going to replace transistor!! Please warn me if doing wrong!

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Willen

Well-Known Member
Look this one first-
www.pira.cz/entx1.htm
-Does it really produce 400mW using 12V power supply?
-I am going to replace 2N3904 instead of BFR91A, and going to replace 2n2219 instead of BFR96.
What will happen?
 
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The original circuit used good high frequency transistors but you are using ordinary "general purpose" transistors that might melt with a supply that is as high as 12V.
The 2N2219 is OK.
 
Design is working efficiently well using 2N3904 devices. There is no point, i feel, inchanging devices for the sake of changing.
 
flat5 said:
We see T1, T2, T3.
Please match your transistor types to these designators.
Click to expand...

try scrolling down and you will see the parts list with the transistor types used

T1 is an audio style BC547
T2 and T3 are BFR96 RF type

Dave
 
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audioguru said:
The original circuit used good high frequency transistors but you are using ordinary "general purpose" transistors that might melt with a supply that is as high as 12V.
The 2N2219 is OK.
Click to expand...

Then what about if I use 2n2222 as a T2? Can it face 12V?
 
An old 2N2222 is in an old metal case. I have never seen nor used one. Its maximum allowed heating is only 500mW but the max allowed heating is 625mW for a newer 2N3904.

A 2N3904 has better high frequency gain than a 2N2222 but both have much less gain than the microwave transistors in the original project.
If the original project has an output of 400mW then with the general purpose transistors its output might be only 50mW.
 
Pleasent SURPRISE, to find you back on this site Bill, after a long holiday !!!!
 
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blueroomelectronics said:
I used to have dozens of the old 2N2222 if I can find one laying around I'll mail you one AG. Now I have hundreds of PN2222 (plastic)
Click to expand...

# Can I use 2n2222 and PN2222 as equivalent of each another?
# Why transistors become old? Or why manufacturer stopped to produce 2N2222 or other old transistors?
 
I still have some old BC107 transistors in the same old metal case as an old 2N2222. I haven't used them for about 46 years but they probably still work.
 
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