[telephone transmitter again not working??]

If you are far from the telephone exchange then your off-hook voltage will be low enough to operate a single telephone. If the phone draws a high current and you are far from the exchange then your voltage will be too low to also power the bug transmitter.

if that is the case then i can use a 9V battery to power the transmitter while connected to the phone line,

what do you think about this battery thing, will it work?

[telephone transmitter again not working??]

But the telephone line's voltage might not be high enough for the telephone and this transmitter drawing current plus some overhead voltage for the regulator and series resistor.

this means that it cannot be done successfully, not a problem,

i will measure the different p.d's around the phone line and post 'em here, and then the circuit can be modified accordingly, is this possible?

[telephone transmitter again not working??]

\
Everty phone line has a different voltage so you won't know what RF frequency it transmits on.
That is probably what your problem is.

hmmmm, that is very interesting, is there a way i can stabilise the voltage using an LM317, or that wont help?

[telephone transmitter again not working??]

thanks a lot for the circuit, i will surely try it adn let you know, i hope it works as i am not sure whether LM2931 is available here, and then later try the phone transmitter, and i will try to post a better pic as i am at takin pictures

i dont know if this is a stupid question or not but i'll ask as i have already asked naive ones before: is there any way your circuit can be converted into a phone transmitter? ::)

[telephone transmitter again not working??]

sorry, the thing is still not working, reversed the pin connections, i dont know what is wrong, please help me, someone, if anyone /?
has time i can even post my circuit to someone interesed so that you can help me out when you have time?????????

[telephone transmitter again not working??]

The pins layout on European transistors like the BC547 are reversed from American transistors like all the ones shown.

yeah even i noticed them in the datasheets, i'll reverse the connections and try, but what if it doesnt work again????? :(

[telephone transmitter again not working??]

yes i made it agian and failed again in this fm transmitter, this time i corrected most of my previuos KNOWN mistakes but nothin on the radio. just cannot figure out why, my friends say i need someone to teach me!

this time i replaced Q2(2N3563) with BC547 and the other transistor is the same, didn't have 5.6pF so replaced it with 5.8pF, i dont think that is the problem though.

i calculated the inductance of the coils according to the instructions given, and they wre not at all close to those mentioned in the instructions[at the bottom of the page http://www.uoguelph.ca/~antoon/circ/FMTelTx/telephon.html ], so i just made the coils as it was given  and not the values given,

can someone help me in this thing i am very frustated with this phone transmitter, i tried them about 10 times but to no avail, someone please help me out here,

[cannot download rapidshare files?]

thanks 'esp1' that worked exactly as you said. the problem was that when i clicked on the FREE button Flashget started to downaload it(a 5KB page i guess), so i had to turn it off to get the job done, thanks,

[cannot download rapidshare files?]

i cannot download the files from the rapidshare site.
the files are in the following thread
http://www.electronics-lab.com/forum/index.php?topic=10085.msg55612#msg55612
i am totally new to rapidshare and dont have a clue how to use it

[crystal oscillator transmitter]

but how do i know which particular crystal is oscillating at fundamental mode or not?

[crystal oscillator transmitter]

the circuits you have linked are really good but i do not think i can construct them. most of the vital parts are not available here, like the FET and ZMV833ATA, and most probably not even the BH1417 ic,

so cant i jsut replace the oscillator part of a regular FM transmitter and replace it with the crystal oscillator?

[555 LED flasher circuit?]

just that simple, and why did'nt i think of that? that's cause i do not know electronics, thanks

[crystal oscillator transmitter]

you mean we can even increase the frequency of an oscillator, that's nice.

but can't i just use a 27MHz crystal and do not get it in the FM band, because i do not want other people to tune into my frequency,  :-\

[555 LED flasher circuit?]

does anyone have 555IC led flasher circuits with atleast 2 LEDs? i had one but i guess i lost it.

[crystal oscillator transmitter]

after having a very unsuccessful time with FM transmitters using "wire" inductors and tunning capacitors, i am turning to crystal oscillators,

so can any one tell me whether a crystal oscillator can be used for audio transmission like an FM transmitter? i have 2 crystal oscillators of 27.xxxMHz from an R/C toy, so is frequency the only difference or there are other draw backs?? and why are there not many audio transmissions on low frequency?

too many question ehh, can you help out???
thanks

[telephone transmitter again not working??]

Two coils have their turns tight together and their wire must be enamel insulated. The other coil has its turns spread apart so it doesn't need insulation. Tinned wire is easier to solder but the circuit doesn't need tinned wire.

exactly, i thought of the same thing and did not worry much about the tinned copper coil,

[telephone transmitter again not working??]

i soldered the replacements with the correct PINs i kept that in mind had their datasheets while soldering them. i also didnot use "tinned copper" wire as the site told[i thought that it will not make a lot of difference] ami correct??

I think the parts are too far apart on your PCB which causes high stray capacitance and inductance.

The project has a PCB that is much smaller than yours. Why not make it exactly the same?

sure i will make it like the original nice and small, i made mine in a hurry,

[telephone transmitter again not working??]

made this fm telephone transmitter and it doesnt work. :'(
cant pick-up anyhtin on the radio, can anyone explain to  me why? ???

replaced Q1 with BC547, and Q2 with KN2222, rest all components unchanged.

[transformer getting too hot.]

AC current through wire that passes through a unknown flux field gives you the frequency based on the number of loops you see?? I've never heard of such a thing... please explain further!!

Are you sure your just not seeing the resonant frequency of the wire... like a guitar string?

here the below files may espolain what i was trying to do, the site does not allow .swf files so i put em in a zip folder,

[transformer getting too hot.]

If you short circuit a voltage supply without something to limit the current then it gets too hot. Hopefully it is a fuse that gets too hot and it blows to prevent a fire.
Keep away from electrical things until you learn the basics.

The mains frequency in my country is 60Hz. It is 50Hz in some other countries. You can't change it. It is easily measured with a frequency counter. My multimeter has a very accurate frequency counter.

The harmonics are caused by distortion, not by length and not by weight.

i knew these methods as well, but wanted to implement my theory stuff.

and the harmonics[or loops] in  the stationary wave were caused by keeping a horse shoe magnet at the middle of the wire, so that the wire was inside a perpendicular magnetic field. and when i passed the current from the transformer it vibrated with 3 loops or harmonics.

the loops which are formed in the stationary wave are linked to the length of the wire and the tension in it[hanged mass from a pulley], the equation for the  frequency of the fundamental mode in a stretched wire is below:

T=tension in wire

[transformer getting too hot.]

i was trying to determine the frequency of the a.c[ i know it is about 50-60Hz] but wanted to find it myself, and also to find the number of harmonics in a fixed length and mass[i got upto the 3rd harmonic at max. with .9m and .15kg]so i simply shorted it out, the thing got so hot that the plastic on which the windings were made melted, even though the room temperature was close to 0` Celcius.

[IC replacment for transistor tester]

i have a CD4047 and also a 4020 IC, which one is a beeter replacement for 4027?

[IC replacment for transistor tester]

what is a good replacement[if at all] for IC 4027 for the transistor tester on this site?

[transformer getting too hot.]

i was using a 1500mA, 12V transformer to find the resonance frequency of a copper wire. but the transformer was getting hot too quickly, within 15mins of its running it was too hot to touch. is it because the circuit was short circuited by directly connecting to the copper wire with nothing else? or is there a problem with the transformer?

[Urgent help for a transmitter]

i did not use a breadboard, i made a PCB from a copper sheet, it measures 3cm x 4cm, the parts are close enough and most of the wires short. but still it is not working. i just dont get it.