Making an FM Transmitter

[vick5821]

Hey there ! Recently I am working on a simple mini project which ia making a FM transmitter.

I get my reference from this website : http://www.minibread.com/modules/blockblog/blockblog-post.php?post_id=5

However, according to the schematic, I am not able to get S9018 transistor and 5.5T inductor. What other transistor can replaced that ? Can I use a 6.8micro inductor instead ?

Thanks for the opinion and help !


Greetings,
Vincent

 

[OLIVE2222]

Hi Vincent,

You can use a BC547 or a 2N2222 or similar for the transistor.
For the inductor 6.8µH will be to high, the BOM state 0.1µH, you can easily made the inductor yourself with a piece of rigid electrical wire of around 1mm of diameter

Olivier

 

[vick5821]

Hi Vincent,

You can use a BC547 or a 2N2222 or similar for the transistor.
For the inductor 6.8µH will be to high, the BOM state 0.1µH, you can easily made the inductor yourself with a piece of rigid electrical wire of around 1mm of diameter

Olivier

What is the reasonable range for the inductor ? possible for me to parallel a few 6.8uH inductor ?

Thanks !

 

[OLIVE2222]

it will not be practical to use paralleled 6.8uH inductors. Really it's easy to made one with a piece of laying around rigid wire turned on a 5-6mm drill bit. If you want a ready made solution you can order a free inductor sample at coilcraft.com

http://coilcraft.com/forms/files/en...essionid=8430da0eb31cb4322fa7181a165667227214

Olivier

 

[vick5821]

it will not be practical to use paralleled 6.8uH inductors. Really it's easy to made one with a piece of laying around rigid wire turned on a 5-6mm drill bit. If you want a ready made solution you can order a free inductor sample at coilcraft.com

http://coilcraft.com/forms/files/en...essionid=8430da0eb31cb4322fa7181a165667227214

Olivier

Rigid wire ? I dont have any for now. I only have single core connecting wires only. Is that possible ?

Thanks !

 

[OLIVE2222]

That's it single core wire, like this:

http://dgysdx.en.alibaba.com/produc...ower_Wire_PVC_Insulation_Electrical_Wire.html

Olivier

 

[OLIVE2222]

PS as the wire is unvarnished stretch the inductor a bit

 

[vick5821]

PS as the wire is unvarnished stretch the inductor a bit

So, I can actually used a single cored wire with the insulator coated to make one inductor ?

Thanks !

 

[OLIVE2222]

It must look like this

http://www.w0qe.com/Technical_Topics/images/1uH_10yr_outside_wire-hi.jpg

Olivier

 

[vick5821]

It must look like this

http://www.w0qe.com/Technical_Topics/images/1uH_10yr_outside_wire-hi.jpg

Olivier

Ahh, I cant find such hard core wire for now. I only have normal single core wire which is quite weak.

 

[CDRIVE]

Ahh, I cant find such hard core wire for now. I only have normal single core wire which is quite weak.

You're not going to be supporting a high rise with it. Trench soldiers worked with much less.

Chris

 

[vick5821]

Hi Vincent,

You can use a BC547 or a 2N2222 or similar for the transistor.
For the inductor 6.8µH will be to high, the BOM state 0.1µH, you can easily made the inductor yourself with a piece of rigid electrical wire of around 1mm of diameter

Olivier

Is it possible for me to use 2N3904 NPN transistor ? Thanks !

 

[OLIVE2222]

Yes you can use a 2N3904

 

[vick5821]

Yes you can use a 2N3904

Actually, how does this circuit works ?
How do I calculate for the transmitted frequency ?

http://www.buildcircuit.com/simplest-and-cheapest-fm-transmitter-do-it-yourselfdiy-kit-for-amateurs/

Thanks !

 

[CDRIVE]

Actually, how does this circuit works ?
How do I calculate for the transmitted frequency ?

http://www.buildcircuit.com/simplest-and-cheapest-fm-transmitter-do-it-yourselfdiy-kit-for-amateurs/

Thanks !

Did you read the description in your link?

Chris

 

[vick5821]

Did you read the description in your link?

Chris

Is that possible for me to measure the output frequency of my circuit ?

Thanks !

 

[CDRIVE]

Is that possible for me to measure the output frequency of my circuit ?

Thanks !

The odds are that you don't posses a frequency counter, grid or gate dip meter or a scope capable of measuring this. This leaves you with what you have, which is the FM receiver itself.

Chris

 

[vick5821]

I made a FM transmitter and the receiver able to receive it. But not stable. Any ways to make it stable and longer range ?

Thanks!

 

[OLIVE2222]

Well this is a very basic circuit, for best stability use a NPO type capacitor for C4 and build the circuit above a ground plane are probably the only possible improvement. For better stability you need a crystal or a PLL.

For longer range you can locate the transmitter in a higher position and/or use a good antenna.

Olivier

 

[vick5821]

Well this is a very basic circuit, for best stability use a NPO type capacitor for C4 and build the circuit above a ground plane are probably the only possible improvement. For better stability you need a crystal or a PLL.

For longer range you can locate the transmitter in a higher position and/or use a good antenna.

Olivier

I am building this circuit,

Thanks!