Been playing with this a bit using my scope i can see the modulation.
Got find a FM radio lol.


Here what it looks like

 

hi burt,
I like that unusual way of mounting components and at the same time having a 0V/Ground plane.

Eric

 

How well does it work? In particular, is it stable frequency-wise?

That technique is an early form of Manhattan style circuit construction.
Manhattan Style Circuit Construction

 

Well it looks to work I looked at it with my scope you can see the modulation
But I think I have to find a better transistor I didn't have a 2SC2001.

But with the scope I can see the modulation when I talk.

I was thinking I have a SDR maybe i can figure where it at on the FM band with it I don't have a FM radio no more lol.

 

Well it looks to work I looked at it with my scope you can see the modulation
But I think I have to find a better transistor I didn't have a 2SC2001.

But with the scope I can see the modulation when I talk.

I was thinking I have a SDR maybe i can figure where it at on the FM band with it I don't have a FM radio no more lol.

Have you got an FM radio on your mobile phone?

 

Here a short video of what the scope showing on the output with me tapping on the mic i think i'm nowhere near the FM band tho.

 

Hey Burt! Haven't I seen the circuit somewhere before!! Ah yes Back to the future ( on Doc's head LOL!! )

Last one I built was AudioGuru's FM transmitter... ( Shown somewhere on another forum ).... It worked great.. I used it for the kids to talk through the radio!!

 

Hello,

Here posted Audioguru his FM transmitter:
https://forum.allaboutcircuits.com/threads/fm-transmitter-help.76738/#post-541536

Bertus

 

Cheers for that! If its Audio's, you know its going to work!!

 

The bandwidth of your scope is 25 MHz which might mean it is insensitive to signals around 100 MHz. What you see is the baseband microphone signal because the transistor is an emitter follower that passes the microphone signal through at near unity gain.

It will be interesting to see what you get with your SDR tuner.

 

Some square pads -

https://aa7ee.wordpress.com/2011/07...ystal-oscillator-and-a-peaked-lowpass-filter/

Some background -

https://www.google.com/url?sa=t&rct.../8505023.pdf&usg=AOvVaw2IwC1OqcPoORGdXaJoor1w

https://www.google.com/url?sa=t&rct.../8411040.pdf&usg=AOvVaw0BL_9WE11Ewc3SHoi6nXvD

Regards, Dana.

Regards, Dana.

 

I'm thinking this thing is more like 3 to 5 mhz LOL

 

It will not work with a condenser mic that needs a 48V power supply. But it will work with an electret mic that has the needed 48V embedded in its electret material.
It will have these problems that I fixed when I designed my FM transmitter:
1) Its radio frequency changes when something moves towards or away from it or its antenna. Therefore I added a buffer transistor at its output to isolate its radio oscillator from capacitance changes at its antenna.
2) Its audio level and radio frequency change as its battery runs down. Therefore I added a low dropout voltage regulator.
3) Its audio level is faint because it needs a preamp that mine has.
It sounds muffled because it is missing the pre-emphasis that mine has and all FM radio stations have.

You will not be able to see FM modulation on a 'scope because the frequency change is extremely small. This transmitter transmits AM and FM at the same time. You will see loud amplitude changes (AM).