[Note:]

How do measure the Brightest White LED and see if it is damaged or not?
thanks

Note: I have tried to test in the same way as the normal LED, but did not give me any reading from both sides

What is the function R3
 If you know that the output voltage at both ends of the 220u capacitor is 9 volts DC, is not this resistance wastes 9mAh all of time
 What is the point of that?
thanks

I read in the book: RF Circuit Design, chapter 4 page 66


How can matching 1000 ohm source with 100 ohm load?
thanks alot

Another reason for using many capacitors in parallel is it gives lower impedance to higher frequencies if they're spread across the PCB traces.

I understand from your words that if I had two caps, one of them is equal to 5p and the second = 10p.
 Better to use the two in parallel to get 15p and not one 15p to make an easy path for the high-frequencies toward ground???

the caps at the right, why 10p//15p? what if use one 25p cap?
thanks

Hi Hero999
I try 4.7k and 470 ohm but the freq remain at 50 MHz
I then changed the transistor to 2N3904 but it still 50MHz
thank you

Yes, it is not Hartley it is colpitts
I have not built this circuit, but I've found it within the ready-made examples in the program
I'm not confident in the results because the frequency stops always at 50 MHz and does not exceed that value no matter how reduced the values of capacitors
Here are pictures of results




thank you Hero999

The Circuit does not respond when I reduce the values of capacitors and inductor for higher frequency, but I am confident that you are true.
Thank you and to  Mr. Hero999

Good
I've implemented Hartley oscillator using a simulation program multisim 10
the first figure was with 6v batt

the freq = 1.15MHz as shown
then i used 9 v batt:

i had the same freq.
please explain that
thank you

Yes, the frequency will go down as the battery discharges

Why scientists not put the battery voltage in the famous expression used to calculate any oscillator frequency?

Ok I get it,

"AM is produced because the transistor's gain alters as the base current is varied and FM because the capacitance between the PN junctions also alters as the voltage varies.
"

BUT: FM is alters as the voltage varies, you mean the voltage of the voice signal, not the voltage of the battery?

in the circuit above, if we omit the voice section with its preamplifier, will remain only the oscillator section
will it change its frequency with change in battery voltage?
thank you

Thank you Hero999, you helped me

To build an FM transmitter which doesn't produce much AM, you need to use a varactor diode as part of the tuned circuit, rather than altering the bias point of the base.

Like this circuit?


Another question:
Why the transmitter frequency change when the battery goes down, despite that the calculation of LC tank frequency does not doesn't take the value of the battery into account?
thank you alot

hi
please look at the following circuit, the author claim it is AM transmitter:



it is from: http://www.zen22142.zen.co.uk/Circuits/rf/amtx.htm

it is look exactly FM Transmitter, the only difference is in the values of capacitors and coils!!!
Is there another difference I did not watch?
Are both circuits were the same?
thanks alot.

The hartely oscillator has many drawbacks as do ther other simple oscillators. It could have to do with the resonant frequency of the LC and the ability to get high enough gain.

Please i didn't understand.

It may also have to do with any change in load conditions that could prevent or stop oscillation.

what if we use a buffer circuit between?

thank you KevinIV