Help Please

[Sceadwian]

I didn't abbreviate high frequency for a reason I meant high frequency relative to modern standards not classic RF terminology. HF in the classic sense is 3-30mhz. High frequency nowadays is in the 2ghz range. Although according to the last U.S. 'frequency allocation chart' I downloaded they have allocations all the way into the 300ghz range, mostly for radio location and satellite applications as at frequencies that high signals are essentially line of site.

I have no experience or idea of the practicality of creating a spark gap style oscillator using a capacitor discharged through an inductor with an antenna tap, especially at that frequency range. I only know it's possible with an amplitude detector and a yagi antenna in the 2ghz range you could create a full wavelength antenna that's only 6 inches long, at that wavelength double or quadruple wavelength antennas are even practicle, given the size you could even print them and use the toner transfer method for etching a very detailed yagi onto PCB.

 

[audioguru]

The very simple FM transmitters you found on the web might be received across a street. Doesn't an arrow go farther than that?

I think you need a transmitter that is better than a simple cheap toy.

 

[Sceadwian]

The transmitter referenced works on pulsed currents through essentially passive analog circuits (a capacitor and inductor), the voltage can be pretty well as high as you have the ability to purchase safe capacitors for (figure a photoflash charged to 300 volts at 80uF through an inductor calculated to resonate at 2ghz) all you have to do is seperate the capacitor and inductor the right distance and the circuit wiring itself will act as an antenna, and the transmit power is incredibly high for the pulses, many miles. The higher the frequency the more directional a yagi becomes with a high number of elements, at those frequencies you could even partially shield the yagi as waveguides are practical.

 

[cyb0rg777]

It just generates a bunch of noise.
I made the coil 30 turns of wire wrap wire and tapped it at 10 .
It just made a buzzing noise all the way across the fm radio and it only worked at about ten feet.

I think it needs more tuning.And more power.My scanner only goes up to 950mhz . Anything higher and I would need a different receiver. I will have to use different transistors anyway because the 2n2222a is only good to 300mhz according to my data .

Anyone have any more ideas?

 

[Sceadwian]

With only 30 turns I'm surprised it worked that well! The noise is exactly what you're looking for, you just need to tune it. I've never done anything like this. (Keep in mind you might be trying to receive on the wrong frequency parasistics and environmental conditions play a lot in this kind of transmitter. EXACTLY how did you construct your ciruit? Pictures would be nice as well as the type and rateings of the components you used.

 

[cyb0rg777]

I wish I could get pictures of my projects with my digital camera.It won't take them that close .Every time I try they end up blurry. I even tried taking them through a 5" magnifying glass but they where still bad.

I took a piece of empty telephone cable jacket since it was about 1/8" and I poked a hole in it and wound it ten times.Then I poked another hole and looped the wiretogether and poked it through that hole and wound it twenty times.then poked it through a hole at the end. I used an 1uf electrolytic capacitor because I wanted a larger one and I don't have anything else that big. Then I wired it together on perfboard and soldered the back. I used a button cell for power.to92 2n2222a transistor, 1/4 watt resistor ,50v capacitor.

wired just like the diagram
**broken link removed**

 

[sam2]

It does not seem pratical, arrows get very beat up when hunting, and more often than not, fall out or are broken off.
There is alot of energy in an arrow, and I just cant see the electronics surviving impact with bone, or a "through and through" into rocks.

Then there is the consideration of the arrows weight and balance, very important if you want to hit your target.

I have used dog tracking set ups and they work good , but the transmitter was large, about 6oz. They were around 200mhz and about 10 miles line of site, but much less in hilly and rocky terrain( 1-2 miles).
sam

 

[HarveyH42]

I'd guess the man's marksmanship isn't great, if he has to do so much wounded deer chasing. Isn't chasing the dee and finding your kill the "hunting" part? Figured there must be more to it then sitting up in a tree stand with a cooler full of beer...

 

[mramos1]

Maybe his cooler is too large and that explains his shots?

Anyway an arrow is to small. It does not seem like a good idea and if the arrow is only $5.

I did by a couple X-bee pro modules, and they are cool. To big for an arrow.

 

[HarveyH42]

It would be kind of cool to make some sort of guidance system. I read something about a model rocket that turns away from the sun (thought sunglasses were a simpler/cheaper solution).

 

[Sceadwian]

Just dont let the FED's find out It's illegal to put guidance systems in model rockets.

 

[mramos1]

Leave it to the feds to wreck all the fun. I can not imagine what it would take to be that small and guide an arrow. A model rocket would be slick though.