1.5 Volt Tracking Transmitter

[forumlicker007]

That is what I'm getting from talkingelectronics. Unfortunately the website is now down!

 

[duffy]

I can just see the movie of the week for this -

Ext. Daytime - a brightly lit field. Two young men are following a signal from a tracking device. One of them holds a directional antenna, which he swaps with the other man as they pass a joint back and forth.
beep... beep... beep...
"Getting closer"
beep... beep... beep...
"Almost there..."

Int. county sheriff's office. An officer is looking through the window with binoculars. Another man sits at a desk.
"Hey Mike?"
"Yeah?"
"I swear, those two stoners are getting closer."

 

[1oskar]

Sceadwian While I'm here =) I almost forgot to ask. Since this is a thread about tracking transmitter's where is the thread about making a receiver and antenna to actually track them? 100mhz is in the neighborhood that hams use for fox hunts but I've not seen any practical receivers or antennas that a hobbyist could build and get to work.
Not much point to building one if you can't receive the signal from a directional antenna.

Good question, no point to make tracking transmitter with no receiver for tracking.I think they must work together.
I was posted transmitter for tracking , but I deal wit such this receivers and directional antenna , but I cannot open new tread, because I am new here.
And I am amateur radio operator, and ARDF or popular fox hunting is something what I know. Most easy way is directional antenna, or something maybe interested Time Difference Of Arrival (in this case FM receiver is good for tracking continues wave transmitter signal)

 

[Bogidar]

I believe colin55's "pot plant" is in fact what would be called a “potted plant” in the U.S. Regardless; I'm not looking to track people stealing from my grow-op. I need a small transmitter to help my nephew and I find our model rockets when they drift into tall grass or the woods.

I started reading this thread because of the circuit based on the IC LM3909. Weight is of course a consideration. What’s needed is a circuit that will let us know, using a regular FM receiver, whether we are in the general vicinity. Would the design that uses the flashing LED in lieu of the now obsolete IC, work for the purpose. I was hoping that the LED may also help us find our rocket at dusk.

Also, I have made an aluminum enclosure to house the circuit. What will that mean for signal strength if the antenna is allowed to trail out?

 

[Sceadwian]

Bogidar, sonic transmitters are more effective than radio onea if you have a general idea of where it landed. Cheaper simpler, more effective. Can't beat the human brain =)

 

[Bogidar]

Thanks for the very practical suggestion Sceadwian. The thought had occured to me. However, this problem has more to do with experimenting with electronics, engaging an 11 year-old boy's mind and having fun with science than it does with actually finding a lost rocket.

 

[1oskar]

Small tracking transmitters however is in use from tracking dogs Radio collars
Like this topic start. OK this is professional device, but this transmitters are not too much complex than transmitters in topic.
Receivers are expensive but not impossible to make.
Also people use professional device for tracking , model airplanes, rocket and even crossbow arrows. But receivers are new thread and I cannot open new thread.

 

[Sceadwian]

You should be able to open a new thread.

 

[woodyboy189]

LM3909 flasher for sale

Before 'PIC' chips were all the rage, tons of real world problem solvers were shipped to Asia. Now you have to look there for the so-called obsolete stuff.

Just googled LM3909...American Micro Semiconductor has it for $5.99, AND for two more weeks - NO MINIMUM purchase! Over 7000 LM3909's in stock. Time to stock up!

https://store.americanmicrosemiconductor.com

 

[Sceadwian]

Sorry woody, I'm a micro controller guy =) (AVR though not PIC, give em a chance they work wonders)

 

[Bogidar]

Could someone please tell me whether the 18p capacitor in the schematic for the second small transmitter discussed in this thread can be replaced with a 16p?

Much appreciated,

Bogidar

 

[colin55]

Any value from 10p to 22p can be used.
It just provides positive feedback to keep the transistor oscillating.
When a transistor is conencted to a low voltage, (such as 3v) the gain of the transistor (the stage) is less then when connected to 9v, and this is why the feedback capacitor needs to be increased from about 10p to about 18p.

 

[forumlicker007]

Values not at all critical. You've to get "beep,beep.." on the fm radio at any frequency. Do by experiments rather than asking simple doubts!! Always have a range of values in hand that'll make you a true electronics experimenter

 

[audioguru]

Values not at all critical. You've to get "beep,beep.." on the fm radio at any frequency. Do by experiments rather than asking simple doubts!! Always have a range of values in hand that'll make you a true electronics experimenter

No.
The Tracking transmitter does not transmitt "beeps".
Instead it transmits pulses of silence. If the FM radio does mot have muting then the background noise between stations will disappear during each pulse of silence.

 

[forumlicker007]

Thank you uncle $crooge for that interesting information. I suspect it for overloading the whole radio band and go for illegal.

 

[Bogidar]

Hello,

When I bought the transistors for this project I was given equivalents. Now like an idiot, I've forgotten which one is which and I'm having trouble finding the equivalency online. They gave me a 2N2904 which is in a round metal enclosure and another one which is black plastic with SPS 2003 M724 printed on the side. Could someone please let me know if these are the right transistors and which should replace which.

Thanks.

Bogidar

 

[Bogidar]

Oooops! Should have mentioned that I'm looking to replace transistors BC547 and BC557.

Bogidar

 

[audioguru]

Hello,

When I bought the transistors for this project I was given equivalents. Now like an idiot, I've forgotten which one is which and I'm having trouble finding the equivalency online. They gave me a 2N2904 which is in a round metal enclosure and another one which is black plastic with SPS 2003 M724 printed on the side. Could someone please let me know if these are the right transistors and which should replace which.

Thanks.

Bogidar

You got ripped off.
The very old 2N2904 is so old that a photo of which pin is which is not available.
Nobody knows about the other one that does not have a normal part number and therefore no datasheet.

Why not buy the correct transistors?
Or go to Australia and buy the kit. Maybe you can order the kit and have it sent to you.

 

[forumlicker007]

BC547 and 557 are very common twins. You may try 2N3904 and 3906 pairs without much modifications. If that one is also not available, forget the circuit.

 

[duffy]

No - use a 2N2222. I built a bunch of these when I was a kid, I know what I'm talking about. The 2N3904 kinda works sometimes, but the 2N2222 is the one you want for the BC547.