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profgoop
06-30-2010, 03:02 PM
Has anyone built their own FM transmitter? I have attempted to build my own and have had very little luck. I have built all types of circuits from guitar effects pedals to guitar amplifiers with a lot of success! Not so much with the FM transmitter. Any tips would be truly appreciated! I have built one small transmitter that worked however it was very weak so I scrapped it. I have attempted to build this transmitter:
http://www.cie-wc.edu/fmtransmitter.asp

I think, that i am having major issues with making the coil. I have used 22 guage wire wrapped around a 1/4 bolt for spacing, aorund a pen, around a McDonald's straw etc... and just cant even get a station to come in.

Trying not to ramble on here but any help would be great!!!
Thanks!!

dirknerkle
06-30-2010, 03:32 PM
While it's fun to DIY various pieces of equipment, sometimes it's just easier to buy it. Many of us use gear bought off eBay for $20-$50, and it's just a lot easier to do that than try to recreate the wheel.

Wombat
06-30-2010, 06:00 PM
Hi Profgoop,

Unfortunately as Dirknerkle said there are somethings easier to buy. When it comes to transmitters especially as they are often unstable. The circuit that you showed there even if you got it to work would be very unstable and often would drift in frequency you wouldn't be able to keep it on the frequency you have put on your sign out the front easily. Little only the power output of this transmitter wouldnt be enough to reach past your house. Most of the commercial ones you buy are PLL locked and boosted by an amplifier, in other words the frequency is determined by a crystal oscillator. This gives very good stability and at least you will be on the frequency you say you will be on.

Go buy a reasonable >500mW PLL locked one from Ebay

Wombat

profgoop
07-01-2010, 12:39 AM
Thanks guys, I appreciate the help. I had just about thrown in the towel on this project but thought I would reach out the experts here! I think that my time would be better spent searching for the best deal on ebay rather than tinkering around with something that may never work....
Thanks again!!
-Chris

budude
07-01-2010, 01:02 AM
Look around for the Vastelec transmitters - a lot folks have them and they're pretty cheap and easy to find.

N7XG
07-01-2010, 10:23 AM
As a person who builds his own radio equipment I would also suggest that if you are planning on using a transmitter for your display that it be rock solid. Starting at around 30 bucks you can purchase a transmitter off of ebay that included a PLL lock feature that will insure that your transmitter will not drift (that is a bad thing).

On the other hand taking on a DIY project like this transmitter is a great experience.

Dean

JP90
07-01-2010, 11:10 AM
I purchased the Whole House Transmitter two years ago and it works great where I live. If you have unused channels at the hi end of the FM band. I added wire to the antenna and ran it outside and got about 250 feet on a free channel, the price is about twice as much as some of the kits on e-bay. They now have a new model 2.0 that will tune the entire FM band in 100KHZ steps and the added a ton of new features, the price is a bit on the high side again but if you do not want to assemble your own case and antenna this unit works right out of the box. I ordered the new unit because of the increased frequency's and because if you bought the old unit from them you can buy this one for $75.00. I called them when I received this new unit because the range was less then the old one and was told by the tech. that there is a small switch in the battery compartment under a sticker and to slide the switch to the other position and in doing so with a tuned ant, just cut the supplied antenna to the proper size, I increased the range to over 350 feet solid signal and it complies with FCC’s part 15 rules (FCC ID: XOAWH-FMT and for Canada it's IC.8728A-WHFMT) well the with the external ant. is says it MAY not comply in the US....... Here is a link to there site. Again the price my be a little high but judge for yourself. These ranges were checked with a car radio not a hand held radio I found that a hand held radio had some drop outs at about 75 feet that may be caused by the wire in the head phones that some of these units use as an antenna.

http://www.wholehousefmtransmitter.com/affiliate-referrals.php

tweist
07-01-2010, 04:26 PM
If you have a transmitter that you can tune or even set a fixed freq on, this web site may help you find a good one for your neighborhood

http://www.radio-locator.com/cgi-bin/vacant

I worked great for me, and I never had any interference.

Good luck.

dmcole
07-02-2010, 12:50 PM
Has anyone built their own FM transmitter? I have attempted to build my own and have had very little luck.

Have you seen this site:

http://www.mikeyancey.com/FM-Stereo-Broadcaster.php

This is going to be a 2011 project for me ...

\dmc

dirknerkle
07-02-2010, 01:25 PM
I keep wondering why there's so much interest in spending the time and money to build a good FM transmitter when for $50 delivered cost, you can get a very good and powerful one with antenna and power supply.

http://cgi.ebay.com/50mW-Digital-PLL-stereo-power-FM-transmitter-ant-power-/260592002285?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item3cac7e64ed

ErnieHorning
07-02-2010, 01:38 PM
... when for $50 delivered cost, you can get a very good and powerful one with antenna and power supply.You know for sure that this is a good one? I looked at one that looked just like it for someone about a year ago. It transmitted almost dead on frequency but it also splattered across the entire FM band. Then I found out that it was wiping out my cable TV too.

He sent it back. Maybe it was just a bad one but unless someone else has had a good experience, its made me steer away from taking a chance on something made in China.

dirknerkle
07-02-2010, 02:46 PM
I used one last year and had zero problems with it -- connected to my dipole antenna it worked just like a dream.

I also have one of the Vastelecs, but that went goofy on me last year in mid-season, I plugged this in and bingo, back up with a clear, solid signal.

tweist
07-02-2010, 05:23 PM
That because you used the correct antenna
With the supplied telescoping antenna you are going to get noise. It is very hard to tune a telescoping antenna, but if you use the Dipole, the quality of the signal is CD quality. Again, its all in the antenna. Transmitters are transmitter, but to get that signal out, unless you know how to tune the SWR perfect, you really need to spend the few extra $ and get the Dipole.

Jrd
07-03-2010, 11:11 PM
I used one last year and had zero problems with it -- connected to my dipole antenna it worked just like a dream.

I also have one of the Vastelecs, but that went goofy on me last year in mid-season, I plugged this in and bingo, back up with a clear, solid signal.

Could you recommend a good inexpensive dipole antenna? I looked on Wikipedia for more information and then looked on eBay for antennas but was unsure which antennas would be good for our uses.

dirknerkle
07-03-2010, 11:20 PM
Could you recommend a good inexpensive dipole antenna? I looked on Wikipedia for more information and then looked on eBay for antennas but was unsure which antennas would be good for our uses.

I made my own for the frequency I was planning to use. It's essentially just a stiff wire taken from some romex cable, cut to the proper lengths and mounted inside some PVC pipe. Lots of designs out there -- but this was a takeoff on the one you can buy from Ramsey Electronics for about $70. I saved about $65 by building it myself.

fathead45
07-04-2010, 12:42 AM
http://cgi.ebay.com/30mW-FM-RADIO-STATION-TRANSMITTER-Circuit-Board-NEW-Ver_W0QQitemZ400091895128QQcategoryZ0QQcmdZViewIte mQQ_trksidZp4012.m506QQ_trkparmsZalgo%3DNGRI%26its %3DI%26itu%3DUA%26otn%3D20%26pmod%3D400075162925%2 6ps%3D63%26clkid%3D7369104562667429126

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=400075162925&ssPageName=STRK:MEWAX:IT

i ordered the 2nd link. i know alot of people have these. seem to work good. cant go wrong for the price.

ukewarrior
07-04-2010, 11:25 AM
i have 'gotten' over a hundred of these to board members and they seem to work very well.
It's what I use in my show. It gives you rock solid 'guts' for a transmitter, yet leaves some room for DIY in terms of connectivity.

Is it time again for me to get some more of these to group buy?


http://cgi.ebay.com/30mW-FM-RADIO-STATION-TRANSMITTER-Circuit-Board-NEW-Ver_W0QQitemZ400091895128QQcategoryZ0QQcmdZViewIte mQQ_trksidZp4012.m506QQ_trkparmsZalgo%3DNGRI%26its %3DI%26itu%3DUA%26otn%3D20%26pmod%3D400075162925%2 6ps%3D63%26clkid%3D7369104562667429126

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=400075162925&ssPageName=STRK:MEWAX:IT

i ordered the 2nd link. i know alot of people have these. seem to work good. cant go wrong for the price.

barnettd
07-04-2010, 01:10 PM
Yes
I would buy one on a group buy!!
Thanks

Jrd
07-05-2010, 12:11 AM
I made my own for the frequency I was planning to use. It's essentially just a stiff wire taken from some romex cable, cut to the proper lengths and mounted inside some PVC pipe. Lots of designs out there -- but this was a takeoff on the one you can buy from Ramsey Electronics for about $70. I saved about $65 by building it myself.

So a dipole antenna could be something as simple as a solid copper 12 awg wire? Is the PVC pipe just for protection and to keep the wire in the same shape or does it actually help with the signal? Is there any reason a WiFi dipole could not be used as an FM dipole?


i have 'gotten' over a hundred of these to board members and they seem to work very well.
It's what I use in my show. It gives you rock solid 'guts' for a transmitter, yet leaves some room for DIY in terms of connectivity.

Is it time again for me to get some more of these to group buy?

So here we have a two board style (http://cgi.ebay.com/30mW-FM-RADIO-STATION-TRANSMITTER-Circuit-Board-NEW-Ver_W0QQitemZ400091895128QQcategoryZ0QQcmdZViewIte mQQ_trksidZp4012.m506QQ_trkparmsZalgo%3DNGRI%26its %3DI%26itu%3DUA%26otn%3D20%26pmod%3D400075162925%2 6ps%3D63%26clkid%3D7369104562667429126) and a one board style (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=400075162925&ssPageName=STRK:MEWAX:IT). These two transmitters appear to have the same specifications and on the one board model there is a buyer question asking how far the signal will be transmitted and the sellers response is 20m which equals 65.6ft. Is this the most that you guys have noticed or can these transmitters transmit the signal farther than that?

dirknerkle
07-05-2010, 12:17 AM
A wi-fi dipole is tuned for a completely different frequency spectrum so I doubt it would be very efficient -- and could conceivably damage an FM transmitter down in the normal FM range.

The PVC pipe is of course for weather protection but also to keep the wire straight and insulated from physically touching anything metal. It also provides a convenient way to mount it.

I was curious last year about whether a copper wire would work -- I had the crazy notion that it should be steel or some ferrous material. So I built one out of the ground wire from Romex cable. Solid copper. Works like a charm.

I posted a PDF tonite in how I built mine -- including the calculation to determine in inches the length of a leg of the dipole.

budude
07-05-2010, 02:59 AM
Great timing - I'm planning to build mine into my LEDTriks panel enclosure.

LabRat
07-05-2010, 09:01 AM
These two transmitters appear to have the same specifications and on the one board model there is a buyer question asking how far the signal will be transmitted and the sellers response is 20m which equals 65.6ft. Is this the most that you guys have noticed or can these transmitters transmit the signal farther than that?

*Significantly Farther*

I have the single board version, and built a dipole antenna using the PVC electrical conduit as the frame. When running in my basement the signal covered the entire street without issue. I then moved the antenna into the garage.

One day while picking up one of my kids from dance, I realized I had the radio in the car turned on, and tuned in to my station at home. The shock was that I was picking up the signal over a KM (~4000 ft according to google maps) away from the house. This year I plan to put the antenna *BACK* in the basement. :oops:

plasmata
07-05-2010, 11:16 PM
I'd be interested in a group buy. Which of the two (single or dual board) is easier to use with a home made dipole antenna? It looks like the single only has solder terminals and the two board has a screw mount.

BTW, Dirknerkle where is your PDF posted?

dirknerkle
07-05-2010, 11:33 PM
The dipole PDF is in the wiki as well as in a current thread for "FM Antenna..."

ncc1701mda
07-06-2010, 01:43 PM
Is it time again for me to get some more of these to group buy?

I too would be interested in a group buy of these.

Mike

Hogfather
07-06-2010, 02:27 PM
I'd be interested in a group buy. Which of the two (single or dual board) is easier to use with a home made dipole antenna? It looks like the single only has solder terminals and the two board has a screw mount.

BTW, Dirknerkle where is your PDF posted?

I noticed that too and have the same question. Looks like to me that it's worth the couple of extra bucks to get the 2 board version just for the mounts alone. I'll be building a dipole as well.

frankv
07-06-2010, 03:37 PM
Are those little in-car FM transmitters any use for this? Or wouldn't they have the power / range? What about if they were connected to a good antenna?

profgoop
07-06-2010, 06:29 PM
I'm in on a group buy. How soon will we know if there will be one?

dirknerkle
07-06-2010, 06:41 PM
Are those little in-car FM transmitters any use for this? Or wouldn't they have the power / range? What about if they were connected to a good antenna?

If you're talking about the kind of thing that connects to an iPod and broadcasts to your radio, they can usually work quite well with a better antenna. All you really need is coverage out in front of your house anyway. There is a lot of information on the webbyweb for modifications to those things, but you have to be willing to take it apart and do a little soldering inside.

ukewarrior
07-07-2010, 10:46 AM
For those interested, I am getting some more FM01's in and the for sale link is here:
http://doityourselfchristmas.com/forums/showthread.php?p=119663#post119663

yosemite
07-07-2010, 12:46 PM
I just bought a whole house FM transmitter but I'm not sure if its the same one your refering to. This one is supposedly "new" version 2.0.
I received it about two weeks ago and have been trying to put it through its paces before I start getting everthing ready. It comes with a USB power cord, battery, and 120 vac adapters and some other accessories. I've only used it with the USB and it seems pretty decent so far. You can dial it to transmit to almost any frequency, It seems to get out to about 125ft from my front window to the street, but only after using the "International antenna extender" that comes with it. Its a piece of 20ga wire about a hundred inches long that you can tune to a full wave antenna. They give you the calculations to do it with.
I have several trees in my front yard that seem to weaken the channel some on a drive by. I just played a few CD's from the Laptop and it did pretty good .Hope this helps.

Yosemite