FM transmitter (mod4) - Page 19 - Electronic Circuits Projects Diagrams Free

bananasiong · 19th December 2006, 04:53 PM

Okay, thanks!
My field strength meter shows only 40mV maximum, when the meter antenna is very near to the transmitter antenna. Both of the antenna are around 70cm long. But you told me that yours can up to a few hundred mV isn't it?

Thanks

audioguru · 19th December 2006, 05:05 PM

My signal strength was measured nearly 2 years ago. I think it was almost 10 times more than yours.

bananasiong · 20th December 2006, 02:10 AM

Wow. But I don't think there is any problem with my transmitter, maybe the meter?

audioguru · 20th December 2006, 02:23 AM

Didn't you add an emitter resistor to the output transistor to reduce its power?

bananasiong · 20th December 2006, 03:01 AM

Oh ya, I did. So this can reduce the transmission distance isn't it? I thought it is only reducing the power dissipated by the transistor.

audioguru · 20th December 2006, 03:53 AM

The emitter resistor reduces the voltage and the current for the output transistor. Power is voltage times current so the power output and heat are both reduced a lot.

bananasiong · 20th December 2006, 04:19 AM

Yes, I got it. Thanks

MALLI · 23rd July 2008, 09:15 PM

i want to know the range of this mod4 transmitter

MALLI · 23rd July 2008, 09:35 PM

please iwant design a fm transmitter with range above 5km please help me

audioguru · 23rd July 2008, 09:45 PM

My Mod4 FM transmitter has a range of "across the street" to a cheap FM radio.
Its range is about 200m to my cheap Sony Walkman FM radio with its antenna attenuator set to "distant".
Its range is about 2km to my very sensitive home stereo and my very sensitive car radio with nothing in between.

10km range will need a very sensitive radio and enough output power to cause interference and is probably against the law without a licence. If you make it yourself then you won't be able to licence it.

Hero999 · 23rd July 2008, 10:54 PM

Don't forget that it's a squaare law so to double the distance you need quadruple the power.

You could try a high gain aerial on both the transmitter and receiver which will boost the range in one direction only.

MALLI · 28th July 2008, 06:21 PM

i want to build this fm transmitter please help me how long it can transmit

MALLI · 28th July 2008, 06:25 PM

what is maximum distance that no need to take licience

MALLI · 28th July 2008, 06:28 PM

please send working & circuit diagram of this fm transmitter

Hero999 · 28th July 2008, 07:18 PM

Use the EDIT button, it looks like this:

The distance this transmitter can cover depends on how sensitive the receiver is and if there any objects obscuring the path.

We don't know what the laws are in your country because you haven't filled your location in.

Look at the start of the thread for schematic of this transmitter.

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19th December 2006, 04:53 PM	(permalink)
bananasiong	Okay, thanks! My field strength meter shows only 40mV maximum, when the meter antenna is very near to the transmitter antenna. Both of the antenna are around 70cm long. But you told me that yours can up to a few hundred mV isn't it? Thanks __________________ Superman returns..

19th December 2006, 05:05 PM	(permalink)
audioguru	My signal strength was measured nearly 2 years ago. I think it was almost 10 times more than yours. __________________ Uncle $crooge

20th December 2006, 02:10 AM	(permalink)
bananasiong	Wow. But I don't think there is any problem with my transmitter, maybe the meter? __________________ Superman returns..

20th December 2006, 02:23 AM	(permalink)
audioguru	Didn't you add an emitter resistor to the output transistor to reduce its power? __________________ Uncle $crooge

20th December 2006, 03:01 AM	(permalink)
bananasiong	Oh ya, I did. So this can reduce the transmission distance isn't it? I thought it is only reducing the power dissipated by the transistor. __________________ Superman returns..

20th December 2006, 03:53 AM	(permalink)
audioguru	The emitter resistor reduces the voltage and the current for the output transistor. Power is voltage times current so the power output and heat are both reduced a lot. __________________ Uncle $crooge

20th December 2006, 04:19 AM	(permalink)
bananasiong	Yes, I got it. Thanks __________________ Superman returns..

23rd July 2008, 09:15 PM	(permalink)
MALLI	i want to know the range of this mod4 transmitter

23rd July 2008, 09:35 PM	(permalink)
MALLI	please iwant design a fm transmitter with range above 5km please help me Last edited by MALLI; 28th July 2008 at 06:41 PM.

23rd July 2008, 09:45 PM	(permalink)
audioguru	My Mod4 FM transmitter has a range of "across the street" to a cheap FM radio. Its range is about 200m to my cheap Sony Walkman FM radio with its antenna attenuator set to "distant". Its range is about 2km to my very sensitive home stereo and my very sensitive car radio with nothing in between. 10km range will need a very sensitive radio and enough output power to cause interference and is probably against the law without a licence. If you make it yourself then you won't be able to licence it. __________________ Uncle $crooge Last edited by audioguru; 23rd July 2008 at 09:45 PM.

23rd July 2008, 10:54 PM	(permalink)
Hero999	Don't forget that it's a squaare law so to double the distance you need quadruple the power. You could try a high gain aerial on both the transmitter and receiver which will boost the range in one direction only. __________________ I also post at the following sites: http://www.stop-microsoft.org http://www.heated-debates.com Screen name: Aloone_Jonez And http://www.silicontronics.com, same screen name as here.

28th July 2008, 06:21 PM	(permalink)
MALLI	i want to build this fm transmitter please help me how long it can transmit

28th July 2008, 06:25 PM	(permalink)
MALLI	what is maximum distance that no need to take licience

28th July 2008, 06:28 PM	(permalink)
MALLI	please send working & circuit diagram of this fm transmitter

28th July 2008, 07:18 PM	(permalink)
Hero999	Use the EDIT button, it looks like this: The distance this transmitter can cover depends on how sensitive the receiver is and if there any objects obscuring the path. We don't know what the laws are in your country because you haven't filled your location in. Look at the start of the thread for schematic of this transmitter. __________________ I also post at the following sites: http://www.stop-microsoft.org http://www.heated-debates.com Screen name: Aloone_Jonez And http://www.silicontronics.com, same screen name as here. Last edited by Hero999; 28th July 2008 at 07:19 PM.