1.5 Volt Tracking Transmitter

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The instructions say to make the coil "close wound". The turns on your coil are much too far apart which causes the frequency to be too high. The wire for the coil is supposed to be insulated with enamel so that when the close turns are touching then they do not short together.

My FM transmitter has "close wound" turns.
 

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How to insulate the coil with enamel? do you mind explaining how to do that?
That means if the coil is further apart will get higher frequency?
My coil is not over frequency but not enought frequency, is it cause of there is no insulation?

Roff said:
Which circuit diagram?
You need to build HF oscillators on a board with ground plane on one side, short leads on all components, and good power supply decoupling.
Click to expand...

erm, I am sorry do you mind explaining more or do you have a link that i can refer to about HF oscillators? I am new to electronics. Thanks
 
yuanong said:
erm, I am sorry do you mind explaining more or do you have a link that i can refer to about HF oscillators? I am new to electronics. Thanks
Click to expand...
I buy Twin 8100 board. You can get it directly from **broken link removed**, or from **broken link removed**. I buy the 10 inch x 20 inch board, and cut off pieces for my little prototypes. You can buy whatever size you need. Use the plane as ground plane. I use 0.1" square grid graph paper to lay out my circuit before I build it.
I have also used single-sided copperclad board and drilled holes and cut pads with a **broken link removed** (I can't believe they cost US $64 ).You can also use the dead bug method (scroll down).
You can also use Veroboard for small circuits that don't need a ground plane.
 
Last edited:

Thanks for the info. But i have already soldered on a veroboard.
I just don't know how to insulate the coil with enamel.
 
I used wire that is made with an enamel insulating coating. I got it from a speaker's crossover coil. A transformer also has enamel insulated wire.

The frequency of your transmitter is too high because the turns on the coil are too far apart. The turns are supposed to be tight together and the wire is supposed to have enamel insulation.

My FM transmitter is made on Veroboard that is also called stripboard because it has parallel copper strips.
 
Now i get what is enamel insulation.
The coil wire i am using are already enamel insulation.
I bought those copper cable from a shop that make transformers and motor.
Thanks for the infomation=D
 
yuanong - wrap it around a pencil and put nail polish on it to hold it together.
 
I used wire that is 1mm in diameter so it is very strong and does not need anything to hold it together.
 
WTF? If you do that you won't have an excuse to buy nail polish! Get with the program.
 
This doesn't look like Veroboard. Is it?
 
Anyway going out 88-108 MHz range not good idea, first if simple oscillator run over 108 MHz this is violation of law(in USA violation FCC rules)
108-135 MHz are airplane frequency , 121.5 MHz are homing distress frequency.
So if somebody live near airport and make a "trip out frequency" unexpected visit from governments are nothing new. Be sure that oscillator not running too long time.(If you not sure exact frequency)
 
hi, i have follow all of the steps that is mention above but the frequency i got from an oscilloscope indicating the frequency is not stable.
Is it the frequency i get from the oscilopscope is incorrect or
Is there anyway to make the frequency stable or have i done any mistake that make the frequency not stable?
 
You can't measure it with a scope, and your layout (although far too blurred to see much detail) looks unlikely to work.
 
May i know what can measure the frequency that it produce?
here is a image that i have redo.
Can please pin point out the mistake that i have made?
is the coil still to far apart?
**broken link removed**
Thanks
 
AG, I don't understand how you build your boards. This one has no solder showing, no cut tracks, and apparently bare jumpers across tracks. How does that work? What's on the back side?
 

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this is whats under it. And sorry my soldering skills is reali bad
those burn parts is at 1st i can solder in the coil.
After i scarpe of the enamel then it only can
but those burn parts i did't use those places
**broken link removed**
or should i just redo the whole thing over?
 
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