i have this circuit that oscillate around 104Mhz ..
i want to know how does it oscillate
and how i can calculate the frequency

 

Applying 3.5V across the base-emitter of a transistor is surely going to blow the transistor. Are you sure there isn't a resistor in there somewhere?

 

[QUOTI'm soryAlbertHall, post: 1269000, member: 240904"]Applying 3.5V across the base-emitter of a transistor is surely going to blow the transistor. Are you sure there isn't a resistor in there somewhere?[/QUOTE]
Oh!? i'm sory i did a mestake I forgot to draw the 7 kohm risistor

 

 

Applying 3.5V across the base-emitter of a transistor is surely going to blow the transistor. Are you sure there isn't a resistor in there somewhere?

I think there's some trick oscillator using reverse biased B/E junction - that could be a messed up representation of it.

 

What is the transistor? What does an upside down V mean? S G O something 8? What is an inverted V6 uH?

Have you built this? Can you show us on a scope?

 

What is the transistor? What does an upside down V mean? S G O something 8? What is an inverted V6 uH?

Have you built this? Can you show us on a scope?

the transistor is npn S9018
the coil is 1.16uH

 

The output cap of transistor is about 1.3 pF. With 1.6 uH....that should resonate around 110 MHz. If you are seeing 104 MHz......that is reasonable.

The coil will separate base phase with collector phase ~90. The capacitance between the base and collector must supply the other 90....to get 180 needed for oscillation.

Most old people would call it parasitic. But hey....why not put it to work? Talk about efficiency!

Have you tried acquiring any power from it? It would seem finicky....might make a good sensor.

Just guessing....not a transistor expert.

 

[QI OTE="BR-549, post: 1269064, member: 218447"]The output cap of transistor is about 1.3 pF. With 1.6 uH....that should resonate around 110 MHz. If you are seeing 104 MHz......that is reasonable.

The coil will separate base phase with collector phase ~90. The capacitance between the base and collector must supply the other 90....to get 180 needed for oscillation.

Most old people would call it parasitic. But hey....why not put it to work? Talk about efficiency!

Have you tried acquiring any power from it? It would seem finicky....might make a good sensor.

Just guessing....not a transistor expert.[/QUOTE]

i built this circuit and i tested it with an FM radio it was oscillate at 104 MHz ... i made this circuit by accident ... that why i don't know how does it oscillate ... i want to know how it oscillate and how I can calculate the frequency i tested it without antenna the range was 10 meters ...


i

 

i built this circuit and i tested it with an FM radio it was oscillate at 104 MHz .... I made this circuit by accident that why I don't know how does it oscillate ... I want to know how does it oscillate and how I can calculate the frequency ... I tested it it without antenna the range was 10 meters

 

Have you ever studied electronics?

 

Yes i'm electronic engineering student

 

Most old people would call it parasitic.
Just guessing....not a transistor expert.

Not an old people expert either.

ak

 

"What does an upside down V mean?"
Ein.

That is a common way for Germans to write "1" - which is why "7" typically has a cross stroke to clearly distinguish it. I presume it is not exclusive to Germany. Commas and periods in numbers are used opposite of how they are many places. 1.000 is one thousand. 1,000 is one, to four significant digits.