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Belkin Tunecast Il FM Transmitter Mod
by The Corrugator on January 18, 2007
Table of Contents
License: Attribution Non-commercial Share Alike (by-nc-sa) .. 1.0... hh hh hh hh hh hh hs 2
Intro: Belkin Tunecast II FM Transmitter Mod 1. usui k poe eee ac Ramo @ a aw: RC RR RE RC c c Od Qo Roa RR KORG NERO IR RR doo Roe 0C REOR URL o eR ee 2
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step 2: The anatomy of a Belkin TuneCastll ... 2.2... 6. suse o RR x eee RES E eee eee dea eee eee wee eee es 3
step 3: What you would see in your brandnew TuneCast, the 'Before’ ...... llis hh hs hh s s a ss 3
step 4: How to boost the FM Transmission power .. 2er nr bee Cbd eed eee UR eee be ORA OR RR ee RR RA KR OX BOR ee eee R A X RO RO RR an 4
step5: Hmm... How about a longer audio cable? « iseasasesusxkesxak swa HR RES AREY eS Ok eR go SO OR m b FU ey ede ew RW EU E DG dee V URL CA Rn 4
step 6: Now to remove the TuneCast auto-power down ............... selle ehh his s he hi s ass 5
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step 8: Just to prove that everything still works and fits snugly! 2... ems s ass 6
step 9: Finaly The finished DEOCUGI. usus d ered aon aia C378 netos SOR ERO Odo des EORR E Bog See anre Roda p dios dio a od dores eWay eee are Gre olog a doe AE qos dieto ege 7
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Attribution Non-commercial Share Alike (by-nc-sa (&) & (9)
Belkin Tunecast Il FM Transmitter Mod
Belkin is a popular manufacturer of cheap and cheerful computer accessories, having singlehandedly made the USB hub sexy! One of their more popular product
hitching the iPod popularity ride, is the Tunecast Il FM Transmitter.
It is only earlier this year (2007) that FM transmitters like these became legal in the UK, ignoring the fact that savvy netizens have already brought theirs from eBay.
This modification improves the transmission range and remove the ‘feature’ of auto-power down when no audio signal is present. It certainly sets you up as resident
pirate radio DJ of your block and allows you to jam the loud radio listener on a bus or train!
Please note that this is a rehash of something that was done before 'instructable' came along. No more the delay now for the good stuff!
Product link:
How to gut the TuneCast
Those ever efficient Taiwanese manufacturer manage to secure this piece of gadget with just a single screw, if you're handy with a screwdriver, that's the job done!
The first image shows the location of the screw (ignore the switch for the moment, that comes later), the second one shows where to a gentle pry will open it, note the
plastic latch.
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The anatomy of a Belkin TuneCast Il
Here's the back of the TuneCast, the IC is a FM transmitter from Rohm, a Japanese semiconductor company.
Image Notes
1. BH1451F FM Transmitter IC
2. Battery power inputs
3. 5V linear regulator and reverse voltage diode protectionn
What you would see in your brandnew TuneCast, the 'Before'
Here's a series of photos of the same TuneCast, thankfully with everything still attached.
Image Notes
1. Wire Identification Blue: Antenna White: Audio Left Channel, 'Tip' Yellow: Audio
Right Channel, 'Ring' Black: Ground, 'Sleeve'
2. Here's where the transistor to keep the TuneCast on without the presence of a
audio signal
3. The pesky inductor that attenuates the transmission power output
step 4: How to boost the FM Transmission power
Well... Not to boost the power, more like removing the attenuation.
This step involves a bit of handy soldering which may be a bit tricky.
Should you dare proceed, the procedure is easy enough, simply bypass the tiny inductor. If you refer to the previous step, you would have notice a blue wire soldered to
the PCB via hole, conveniently labeled 'ANT', remove this and stick it directly to where the black wire is on the photo below, the inductor can be left connected to one end,
just in case you wish to revert the changes.
An adequate length of this black wire for the antenna can be a quarter of the transmission wavelength, in this case, a minimum of 3e8/10866 * 4 (c = f * lamda), about
70cm.
Now if you wish to take it further, get a telescopic antenna! | have devised a neat way of attaching the antenna, see second photo.
If you live in the UK, Maplin Electronics (www.maplin.co.uk) has a selection of antenna for CB radio
Image Notes Image Notes
1. Inductor to bypass 1. A screw-on fitting for telescopic antenna
2. Reattached antenna wire here
3. Unsolder blue wire from here
step 5: Hmm... How about a longer audio cable?
Yup, the TuneCast has a really weedy short audio cable, not very nice if you decide to place the FM transmitter by the window, so your neighbor 4 floors down can listen
to your collection of the latest break-beats!
The solution is to replace the stereo plug with a plug that is small enough to still fit the TuneCast package.
The photo below shows the new stereo plug add-on feature, if you're doing the modification, do note the correct channel, refer to the photo in step 3 for the correct
connections.
A brief description:
The white wire is the 'tip' of the plug, which is the left channel, the yellow wire connects to the 'ring' or middle bit of the plug, which is the right channel, the black wire is
the ground.
Suitable stereo socket can also be found in Maplin Electronics.
step 6: Now to remove the TuneCast auto-power down
Basically the TuneCast automatically power down when there's no audio signal for about a minute, this is great since the number of transmission channel is limited, not
so great when you are flipping through your 60GB of music selection looking for right song and then a blast of static comes on! Ouch!
This step is a bit trickier, it involve adding a switch, a resistor and some wiring.
The idea works by biasing up the bit that turns on the TuneCast when a audio signal is present. Although the transmitter is battery powered, many of the ICs on the
device requires a higher operating supply voltage, this is done with a boost converter, boosting its internal supply to around 5V, where it is kept permanently 'on', which
partly explain why your TuneCast is dead after a few days even if you're not using it, pretty dismal, but great for this modification!
Note on the photo below, the two point in which the wires are attached is where you need to modify ( incidentally, this is at the top right end of the PCB, on the LCD side)
. | choose to use enamel wire, which has a coat of thin insulating enamel/plastic, simply scrape the ends to allow soldering.
The second image is a drawing of the circuit connection.
As promised, with this feature allows you to 'swamp-out' a typical commercial FM station within 2 to 3 meters of the transmitter and enjoy the peace and quiet. Not
dramatic but enough to convulse the listener into fiddling with the radio tuner. ;)
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Image Notes
1. Point A, top left 'leg' of SMD transistor
2. Point B, boosted supply voltage
Modding the case to fit the switch
Now that you have done the tricky bit, here's the horrible bit! Wedging a tiny switch into the TuneCast casing. Any kind of on/off bistable switch is suitable, except for
momentary monostable push switch, of course the smaller the better, the one I use is massive, but you do with what you have.
With a fair bit of filing and drilling, the end result is show in the photos below.
Just to prove that everything still works and fits snugly !
What you would have done if you had dare ventured! It's alive!
Finally! The finished product!
To take it further, you can make a plastic clip mount with a mini-camera tripod and you have your own FM base station!
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Comments
|50 comments Add Comment view all 134 comments
Joby1664 says: Nov 7, 2009. 3:38 PM REPLY
My Tunecast was different to the one in the example when | opened it. | couldn't find the inductor so | soldered the antenna to one of the legs of the
transmitter chip which seemed to be producing the signal. Will this produce the same result or have | made a mistake?
| can't see the equivalent components to bypass the auto shut down either.
gprix1 says: Nov 6, 2009. 3:03 PM REPLY
What did you use for the plastic piece on top of the tripod? How is it holding the transmitter?
MairseyDotes says: Mar 9, 2009. 10:56 AM REPLY
Replacing the cable seems like a lot of unnecessary work; just use a 3.5mm stereo headphone extension cord.
thx0138 says: Mar 13, 2009. 7:35 AM REPLY
Agreed. The antenna mod is great, but it's not much more money and a lot less work to just use a headphone extension cord for this part.
Sep 16, 2009. 5:12 AM REPLY
wquoyle says:
i Trouble is the audio cable/plug is awful quality, l've had to solder on a new plug three times so far on my Tunecast due to the cable wearing and
shorting out. Dumping the cable and installing a socket is the best mod you can do.
elantrix says: Aug 30, 2009. 6:14 AM REPLY
Can you also add a way to solder a DC plug into it.
Last Liberal says: Jul 18, 2009. 5:51 AM REPLY
(I apologize for the repeated posts, but I'm not getting any feedback.)
Other then that, it's a pretty nice mod.
| was able to complete the mod and it did dramatically improve the output of my Tunecast (great), but for some reason, l'm only getting the Left channel (no
sound from my Right speaker) even thought the "stereo" light is lit on my receiver noting it detects a stereo signal. And yes, the speaker plays fine when
switched to regular radio.
I'm also getting enough "hiss" to be annoying (no matter what station | choose).
Anyone have any ideas?
Jul 17, 2009. 3:11 PM REPLY
italodisco71 says:
P d See this video my friend.
http://www.youtube.com/watch?v-LsZw youJAo
Last Liberal says: Jul 11, 2009. 8:15 PM REPLY
| am seriously confused here. You are connecting BOTH the blue antenna wire AND a separate external antenna to the transistor (?) in the middle of the
photo (does it matter what end you solder the wire to? Both ends? And how is the inductor "bypassed"? Do you cut one of the leads or run a wire around it?
(or both?)
Please help.
Last Liberal says: Jul 13, 2009. 9:48 AM REPLY
Okay, | think | have it now. After blowing up the photos, it appears you soldered a bridge between where the inductor was connected to the left 'L6'
= contact (the two L6 contacts do not appear to have been bridged), where you also connected the external antenna (the internal antenna does not appear
to have been reattached).
If I'm mistaken, someone please let me know. Thx.
italodisco71 says: Jul 13, 2009. 7:07 AM REPLY
"d This belkin fm transmitter haves 2 chips. One, Amtel Eprom and one Toshiba with programm and up down 88 - 108. See the youtube video how to convert
this transmitter! http://www.youtube.com/watch?v=LsZw_youJAo
dj Kostas http://myitalodisco.blogspot.com
graveyardskank says: Jun 9, 2009. 3:51 PM REPLY
really good plans, simple and effective. took me about 10 minutes to do this and the audio quality is perfect over 5 meters, have yet to take the radio further
away to asses the range but i am very impressed.
transmitter broadcast is strangely directional from the telescopic rod and needs to be angled straight up, gonna be looking for a better shape for omni-
directional transmission but its awesome just as you described.
Last Liberal says: Jul 11, 2009. 9:49 AM REPLY
10 minutes? Yeesh!
I'm having a little difficulty seeing *exactly* where the new antenna wire is being attached or how the inductor was bypassed. Can anyone clarify? Thx.
robot+more says: Jun 29, 2009. 10:51 AM REPLY
i don't want to mess with the signal so can i put a power antina from a car on the antena of the radio
Biotele says: Jun 12, 2009. 4:58 AM REPLY
What is the farthest you can transmit with this mod?
pigmeat says: Apr 18, 2008. 7:01 AM REPLY
| have a Belkin copy, by a company called Sansai (see image) and it works great, but I'd like to modify it with guidance from your instructable post. My only
problem so far is getting the damn thing open. Unlike the Belkin this thing has no screw and | had a hell of a time trying to pry it open (without success). Has
anyone here managed to open one of these? If so, how did you go about it?
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mdphoenix says: May 26, 2009. 2:31 PM REPLY
| know this is a year old but:
| have a similar unit. Mine is made by iWave though. The gray bezel around the front comes off and the screws are under there. My board was different
but | could still locate the attenuating inductor just above the antenna solder joint.
Good luck.
richms says: May 28, 2008. 4:10 AM REPLY
| don't know if you have got anywhere with this, but the one pictured is a hugetide c-007B - the black cover with the « O and » buttons will come off (held
on with tape) and there's 3 screws under it. | am still playing with defeating the auto power off on mine, when | have some luck | will post an instructable
here.
lo
pigmeat says: May 30, 2008. 1:23 AM REPLY
Thanks for this. | have since got another model with a screw and have opened it up. Yet to do any mods as other projects are more urgent.
mdphoenix says: May 27, 2009. 6:51 AM REPLY
Out of curiosity, what DO the « o > buttons do on yours? | don't have them, but the spaces for them are under my bezel.
danielelspeet says: May 5, 2009. 6:10 AM REPLY
Can you also make the signal better, by making the blue wire longer?
emherrma says: Apr 28, 2009. 10:26 AM REPLY
Great mod!. | see a 29dB improvement
ferralll says: Apr 8, 2009. 4:37 PM REPLY
| did this on my wife's Tunecast, and now it works great. (or atleast part of it)
Before, if you were around a city, you would need a lot of luck to find a good station. Now, | can beat out most of the non major (local) stations! Thatsk.
What | did (if any one wants to know) | used a good soldering iron, and some VERY thin gold wire (did at work under a microscope) and just made a shunt
around the Inductor that you ripped out (ripped up).
It works great, and turned it from almost useless, to very effective.
| am now trying to do it to my brother in-laws Belkin TuneFM.
(this one is much more difficult to open, and the components are much smaller and closer space. If | get the chance, | will post pictures.
thatsmyfox says: Apr 1, 2009. 5:15 AM REPLY
| have a diferent version again!
The unit really does need this hack though because the range is pants.(UK)
Wish | had smaller fingers - | would do this one....
JakeFrost says: Mar 25, 2009. 7:31 AM REPLY
' Just finished my upgrade of the Tunecast original, and | am amazed. Where | live there is a station on all four of the presets, now | can use it on any of them.
| get about five to ten feet around the transmitter. This is my first upgrade using instructables, but not my last. Thanks
marcward66 says: Mar 23, 2009. 7:35 AM REPLY
your efforts are appreciated!
i had a tunecast original, and it used to suck, but now it's awesome!!!
testoffer says: Mar 8, 2009. 10:58 AM REPLY
Nice instructable. Your one limitation now would be battery life. You can solve this by getting one of those cheap AC converters that outputs 3 volts DC. Cut
the plug off at the end of the output line, strip the end of the wires, and hook up the + and - to the appropriate terminals of the battery connectors of the
transmitter.
brian2012 says: Mar 8, 2009. 8:31 PM REPLY
actualy modding that part would be pointless, i have one of these and even notice on the first picture on the bottom that little hole, its for an AC adapter.
But good idea tho.
remork says: Aug 20, 2008. 6:34 AM REPLY
Hey, | have the same Belkin as the first commentator on this page (called Lappy).
| have included a picture of it.
But as my German is superrusty, | don't really understand where to solder the antenna. Is the black element with R18 on it the inductor? On what side of it
should | solder de antenna? thanks :-)
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h4d32z says: Feb 19, 2009. 6:25 AM REPLY
Having the same problem
E The board has a H18 thing
How do i mod it ??
acer5050 says: Feb 2, 2009. 2:14 PM REPLY
| did a similar mod to the same unit... | live in a small trailer and its range is about half the length.. its not good for a pirate radio station lol but it'll get music to
ur radio...
acer5050 says: Feb 1, 2009. 11:22 AM REPLY
| had the black tunecast 2 and the stereo wouldn't pick it up at all/very little. | had to put it on the antenna and still got tons of static..
| soldered a 1ft wire onto the black thing described in your instructable and now I can use it clear acrossed the house! thanks man :)
turbomod says: Dec 27, 2007. 8:00 AM REPLY
have a completely cheap and nasty virgin megastores version worth £8. have bypassed the attenuation with some 50 ohm coax got about 15feet of it
stripped about 2 foot back and pulled the screen down over the insulation. hung this in my attic and was capable of receiving my signal quite clearly up to
1km away whilst stationary, this is down hill from the antenna, up hill there were too many houses blocking the signal, if i could get it higher i think I'm on to a
winner, when it finally went out of signal there was another station their so i was very shocked
SeVy says: Jan 4, 2009. 5:09 PM REPLY
Is the tunecast's power still the same,even when transmitting for a kilometre with a decent antenna? as turbomod.
Would | be legally able to do this in the uk?
X. | ReCreate says: Jan 27, 2009. 8:40 PM REPLY
/ | of course you can do it in the uk
SeVy says: Jan 29, 2009. 5:10 PM REPLY
Im not sure you can do it in the uk.From what lve read,bypassing the attenuator would take its transmit power over the legal limit.
Am | wrong??
||
| 4$ | ReCreate says: Jan 29, 2009. 8:09 PM REPLY
i dint think so
SeVy says: Jan 30, 2009. 11:50 AM REPLY
, The legal power limit in the uk is 50nanowatts.
Can anyone tell me for sure whether bypassing the attenuator will increase its power past 50nw??:)
| «x | ReCreate says: Jan 30, 2009. 1:30 PM REPLY
f | probably such a tiny thing is not capable of broadcasting more than that
| you could however modify a signal booster or a rf booster to to increase the nanowatts
who knows?
SeVy says: Jan 30, 2009. 2:41 PM REPLY
, Eggs act lee,who knows.
| have http://www.amazon.co.uk/LUPO-Portable-Transmitter-Modulator-
Channels/dp/BOOOSOXBE4/ref=sr_1_3?ie=UTF8&s=electronics&qid=1 23335451 2&sr=8-3
| can attach an external aerial anywhere on the circuitboard and | get about 300metres distance.Im looking to get around 1
kilometer (so my friend can tune to my internet station,he doesnt have internet).
My objective is to copy what turbomod did but to keep within 50nw,if possible;)
| dont want to increase the nanowatts but get the most out of 50
krunal800 says: Mar 26, 2008. 6:46 AM REPLY
hey awesome instructable........ i opened up my psp fm transmitter and connected an rc remote antenna as the aerial and the range has increased to about 5
times the original range....... once again awesome instructable dude!!!!
here r some pics:
ReCreate says: Jan 27, 2009. 8:50 PM REPLY
hey where did you get that transmiter?
btw i have a psp except its the silver one
krunal800 says: Jan 28, 2009. 12:09 AM REPLY
i cant remember exactly but i think it was from argos in uk
jb23rdmc says: Jul 17, 2007. 3:04 PM REPLY
Hi what do i do with the blue wire? do i need to connect it any where plz answer my question|@!@'!@!@
Strikah says: Nov 7, 2007. 1:28 PM REPLY
My thoughts are that the blue wire is removed and the black wire is now being used as the wire to the antenna. This is just my speculation.
Strikah says: Nov 7, 2007. 1:35 PM REPLY
Sorry for double post, but if you look closely at the inductor and compare it to step 3, it has been taken out on one side
amzzzziohi says: Dec 25, 2007. 8:59 PM REPLY
Soz but l'm still confused. Could you plz explain in a lil more detail what exactly you do with the black and blue wires? Thx I'm trying to figure it
out but I'm not sure and | wanna be before | do this.
connected to an external antenna and is therefore connected back to the FM transmitter. If | look even closer, you see that the Inductor has
been removed on one side. On that side you'll have to solder the Antenna. BUT then again, | haven't tested it yet. So if you want to do it, it's
at your own risk!
amzzzziohi says: Dec 26, 2007. 4:37 AM REPLY
Ok thank you. | started to study all the pics closely and | came to that conclusion. | hope urs works lol if you did it. I'm gunna try it on my
Belkin Tunebase (the one that plugs into the base instead of the earphone jack). | have a basic understanding of circuits, | made a circuit
for a flashing LED for a school project lol. I'll get some help from the 'techno' guy at school. He once made these awesome speakers and
bought 'em to a carnival.
Strikah says: Dec 26, 2007. 3:33 AM REPLY
It's not like | have done this, but when | look at the pic. The blue wire has been removed and is thus no more used. The black wire, is now
shaunp says: Jan 13, 2009. 12:39 AM REPLY
Cheers Buddy, OK well | bought two of the Belkin Tuncast Il, and performed the Above on one of them. Now What | found is that on
mine above the inductor (which is black and more cube shaped) is a small resistor were the black antenna is soldered in the above
pic. So for testing i just used a small 10cm piece of braided wire and by hand put it on the (LCD Bottom Down Side) leg...and it
improved the signal to quite a bit. Now After trying this is decided to get the solder iron out and after try to attach the new Ant to the
spot basically the same as above but on the left leg of the resistor. In the end i basic shorted the resistor. So imagine the above
picture were the new (black) ANT goes is actual covering up the Resistor...Now the Inductor is still in the same place and has not be
moved at all and the main (blue ant) is still intact and attached. Now this works better than the other unit.( Non Mode) But still can't get
than 3 meters away without signal Degradation. Should | remove the old ANT? (Was going to anyway). when you say remove the
inductor do you mean just lift one leg off the board a slight. And in your above picture did you have a small Resistor under the Solder
of the Black Wire(ANT)? If not what exactly are you soldering on two is there a Silk on the board at all list say R16??.
the above steps that i took seem to work to my Satisfaction as i just wanted it to be in the backseat of the car or Glovebox...But on the
other belkin that i have not even opened yet. | wish to perform the same mod but hopefully would be better Transmitting
Distance...hence this time i will run the wire out of the device to see how much improvement it will make...Any help would be
great....Basically just need to know whether i was suppose to solder the new ANT over the resistor above the inductor(Can't bee seen
well enough in PIC above...but were the Black wire is attached | have a small resistor(l think it's a resistor)..Will take Pic's when have
CAM Hangy...
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