I`ve tried two circuits
one from the site: http://www.aaroncake.net/circuits/fmtrans.htm
and the other:
Trouble with FM transmitters
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Alan Smith
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Trouble with FM transmitters
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Alan Smith
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Rescyou
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Pieces
Did you substitute any components? Have you tried it with different variations for the inductor? Have you checked and ensured that all components are in the right orientation?
S.
S.
The mind of a man is the man himself.
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Alan Smith
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Rescyou
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Parts
Is there any markings in the vari-caps and/or manufacturer so you can look up the exact specs?
Sometimes these things have a very small range on the radio, much less than a radio station so when your testing, do it with the volume cranked on the radio and move the dial real slow and then adjust the vari-cap a small amount and go through the full range on the radio again. You also should generate a test tone with any available means you can, I'd suggest something on the computer if you have that capability. Record a wave file on the computer of you humming a note and then have it repeat in the player and put your mic to the speaker and test the transmitter.. But the speaker may give you interference... FM transmistters are a pain.
I've never had much luck with FM transmitters from custom circuits. I use infrared/laser for transmission as most of my stuff is "line-of sight".
If you go here and post the same questions, these guys will be able to help you out a lot better:
http://www.electro-tech-online.com/
S.
Sometimes these things have a very small range on the radio, much less than a radio station so when your testing, do it with the volume cranked on the radio and move the dial real slow and then adjust the vari-cap a small amount and go through the full range on the radio again. You also should generate a test tone with any available means you can, I'd suggest something on the computer if you have that capability. Record a wave file on the computer of you humming a note and then have it repeat in the player and put your mic to the speaker and test the transmitter.. But the speaker may give you interference... FM transmistters are a pain.
I've never had much luck with FM transmitters from custom circuits. I use infrared/laser for transmission as most of my stuff is "line-of sight".
If you go here and post the same questions, these guys will be able to help you out a lot better:
http://www.electro-tech-online.com/
S.
The mind of a man is the man himself.
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Pieter van Boven
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Alan Smith
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I`ve already tried everything using the computer. The variable caps i have don`t have any markings on them whatsoever.
About the "line of sight" circuits, i`ve always wanted to make one of those, but they have restrictions. I need the circuit to communicate over a distance of about 200-400 meters (656-1312 feet) and it`s not in sight range due to trees, buildings... I have no possibility of placing signal relay circuits around the place. I`m thinking of just abandonning this project, or sending the cicuit to a profesional.
AM transmitters whould work betted maybe. The AM band isn`t as much crouded as the FM band, it`s actually empty. But static would have a lot of interference on the signal...
I got the site but i`m not gonna post this topic, it`s better to post about high-tech stuff when i get to them.
About the "line of sight" circuits, i`ve always wanted to make one of those, but they have restrictions. I need the circuit to communicate over a distance of about 200-400 meters (656-1312 feet) and it`s not in sight range due to trees, buildings... I have no possibility of placing signal relay circuits around the place. I`m thinking of just abandonning this project, or sending the cicuit to a profesional.
AM transmitters whould work betted maybe. The AM band isn`t as much crouded as the FM band, it`s actually empty. But static would have a lot of interference on the signal...
I got the site but i`m not gonna post this topic, it`s better to post about high-tech stuff when i get to them.
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Rescyou
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QKits
If you are thinking of going the way of AM I've use some of these devices from this place before:
http://www.qkits.com/serv/qkits/qkitsca ... =4&ccat=RF
Check out the RX433 + TX433 kits. Cheap too but I can't recall the range.
They actually have quite a bit of goodies on the site, have a look through the RF section as they have many transmitter/receiver type kits.
S.
http://www.qkits.com/serv/qkits/qkitsca ... =4&ccat=RF
Check out the RX433 + TX433 kits. Cheap too but I can't recall the range.
They actually have quite a bit of goodies on the site, have a look through the RF section as they have many transmitter/receiver type kits.
S.
The mind of a man is the man himself.
A simple RF-voltmeter is very useful to see if the oscillator really oscillates or not.
Just solder together two diodes like 1N4148 or similar this way: ->I-->I- and connect the cathode (left side) to negative terminal and anode to positive on a analog multimeter (use the DC lowscale).
Oh one more thing, a short piece of hookupwire between the diodes to act as "probe".
Use the probe to touch transistorcases and souch when in doubt if you have any RF or not, might bend the needle on the mV scale, better use the 0,5-2 or something.
You can also just get rid of everything to the left of C2, it´s just a mike amp you dont really need with electretmicrophones.
the resistor feeding the electret (+) must be included of course.
Just solder together two diodes like 1N4148 or similar this way: ->I-->I- and connect the cathode (left side) to negative terminal and anode to positive on a analog multimeter (use the DC lowscale).
Oh one more thing, a short piece of hookupwire between the diodes to act as "probe".
Use the probe to touch transistorcases and souch when in doubt if you have any RF or not, might bend the needle on the mV scale, better use the 0,5-2 or something.
You can also just get rid of everything to the left of C2, it´s just a mike amp you dont really need with electretmicrophones.
the resistor feeding the electret (+) must be included of course.