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FM Transmitter w/ Optional Charging USB Port
In Stock This item should ship today (11/27/2015) if ordered within 6 hours 21 minutes

0.34 lbs

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  • 0-3lbs- $4.99

FM Transmitter w/ Optional Charging USB Port

So you love listening to your own music, but don't have an auxiliary port or tape deck in your car? What you need is this FM Transmitter with optional charging from Monoprice!

This FM transmitter can transmit the selected FM frequency to your car's radio in order to play music from your smartphone or MP3 player. Simply select an open radio frequency on the FM transmitter, and tune your radio to the same frequency. Any music played through the transmitter will play through your car's sound system.

The transmitter can be tuned to any FM frequency between 88.1 ~ 107.9 MHz at 0.1 MHz intervals. It has a frequency response of 20Hz ~ 16KHz and an effective range of about 5 meters.

The FM transmitter's 3.5mm plug can be used to connect to most smartphones and MP3 players' headphone jack. It uses your car's cigarette lighter/auxiliary power socket for power, so you don't have to worry about the battery dying during your favorite song.

The transmitter also includes a USB port that can be used to charge your devices at any time.


  • Wireless audio transmission over the entire FM frequency range
  • Works with almost any smartphone or mp3 player
  • Folding 3.5mm TRRS plug
  • Built-in microphone lets it function as a hands-free communications device
  • Rechargeable lithium battery
  • Includes car charging cable adapter with an additional USB charging port
Model 10403
Transmitter Frequency 88.1 ~ 107.9 MHz
Frequency Tuning Interval 0.1 MHz
Stability 10 ppm (+14 ~ +131°F)
Clutter & Harmonic Distortion < -60dB
Effective Range about 15 feet
Frequency Response 20 Hz ~ 16 KHz
Stereo Separation 40dB
Audio Distortion < 0.1% (F=75KHz, f=1Khz)
Signal/Noise Ratio > 45dB (1KHz 100%)
Dimensions 2.3" x 1.2" x 0.5"
Weight 0.6 oz.

39 Reviews

70.51% of the reviewers recommend this product


High powered bt short lived

  • chief0,
  •  Arlington, MA 
  • 8/3/2015 4:26:48 PM

Pros: High powered.

Cons: After about 18 months, it will no longer take a charge.

I use mine to transmit from my SanDisk mp3 player to my car radio. High powered to overwhelm weak stations so you don't have to change channels too much as you travel. Lasts more than 4 hours on a charge.

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Useful to dangerous in a matter of seconds.

  • mos6502,
  •  Saint Louis, MO 
  • 6/22/2015 10:59:54 AM

Pros: Wasn't hard to use, and I keep mine plugged into the included power adapter so I don't need to rely on the battery. Found a dead zone not used by local stations, and voila, I've got audio over FM.

Cons: Very intermittent quality/functionality. Not worth the distraction while driving. Works solidly when you're stationary and have spent some time finding clear FM space, but after you start moving... it'll start acting up and you can either continually pull over to keep fiddling with it, or give up and turn it off.

This thing works nicely when it works, but seemingly out of nowhere the audio quality to degrade, or it will cut out completely. It will also, for no apparent reason, activate Siri on the iPhone I'm connecting it to - sometimes I can do an entire drive with neither problem occurring, other drives, it's just a barrage of problems until I turn it off. People use these in their cars primarily, and I'm one of those people - I've for the most part given up on using the device, since when I do, it's downright dangerous. I've nearly caused accidents a number of times because suddenly the transmitter's signal cuts out and I'm being blasted with static, and I'm frantically reaching to turn it off or readjust, or I have to grapple with my phone to get the audio playing again. I understand that it's my responsibility to refrain from activities that distract me while driving, so with that in mind the transmitter is useless. And if you are considering buying this for a teenager, DON'T, I can't imagine how dangerous it would be in the hands of a less experienced driver.

by Monoprice Administrator
Hello mos6502,

My apologies for the inconvenient experience you have faced while using PID 10403. If I may ask, is there any difference made when the transmitter is placed in different areas of the car? Such as, does the audio clear up when the transmitter closer to the dashboard? What about when other frequencies are used? Also, has this issue been present since the transmitter was first received? Please let me know so we can best assist you with this matter. Truly sorry again for the trouble and thank you in advance!

Gabby V.
Tech Support Associate

by mos6502
I appreciate the response.

I usually have the transmitter sitting within a foot of the receiver. I've done a lot of playing around with different variables to improve performance, and this is exactly the trouble... what works one day won't work the next and I'm left having to adjust it frequently while I drive, which I've had to stop doing.

It's behaved like this since I got it, but I didn't make a fuss over it for some time simply because I thought that if I kept fiddling around with it long enough I'd find that sweet spot of location and frequency that would make it work consistently. But that just hasn't happened.

by Monoprice Administrator
I see, thank you for the additional information! Unfortunately it appears as though you have received a defective unit. I will submit a complaint regarding the audio quality issues as well as Siri turning on randomly. If you would like, we can try a replacement unit to see if it will work out any better for you. This transmitter is covered with a one year warranty and it would be of no additional cost to you to obtain the replacement. If you wish to proceed, please let me know and I will get that started right away.

Gabby V.
Tech Support Associate

by mos6502
Thank you for the response. I have been playing with it again recently in light of posting this review, and sure, if you want to send a replacement I could try that. I honestly don't know if it would solve the problem because I suspect it's just how the device was designed (not optimal for my needs and/or environment), but I will give it a shot.

by mos6502
I received the replacement, thank you. I will create a new review as soon as I get around to trying out the new one. At a bare minimum I am very happy with the customer service, as I didn't expect anything from Monoprice when I posted my original review. Much appreciated.
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Nice, compact FM transmitter

  • Colin Weiss,
  •  Chicago, IL 
  • 5/23/2015 11:49:27 AM

Pros: Very compact
Good battery life
Standard MicroUSB charging port
Strong enough signal
Good audio quality
Does not turn off randomly when volume gets low like others I've owned

Cons: So small that I lost it once, but I found it again! Yay!

This little FM transmitter is great. The plug flips out and it just sits on top of the 3.5mm headphone port on whichever device you're using. I can see this being a problem if you have a thick case around your device, but seriously, buy an extension cord or adapter if that's an issue. I'm that is the problem with most people saying that it doesn't stay in, because I have no problem with mine when it's flush with the port.

The audio quality is definitely acceptable for an FM transmitter. The signal strength is fine especially considering I live in a large city with lots of radio stations and my car is missing its FM antenna.

Every other FM transmitter I've owned has had one issue or another. Either the signal isn't strong enough, the battery life is bad, turns off when the volume of the music gets too low, etc. But this one doesn't seem to have any of those problems, and it's cheaper than most of the other ones I've had. Definitely a good purchase.

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Very poor fit

  • Trevor ,
  •  Lethbridge, Alberta 
  • 5/15/2015 2:00:46 PM

Pros: Cheap, rechargeable lithium battery is a nice idea.

Cons: very bad design. Does not stay in place when connected and falls out easily. The fact that the 3.5mm jack folds is not a useful feature, and in fact it would probably stay in place a lot better if it didn't fold.

Waste of money. Nice idea but poor implementation. Mine is probably going in the garbage. It's not even worth shipping it back for a refund.

by Monoprice Administrator
Hello Trevor,

Thank you for your review on this FM transmitter! Sorry to hear the 3.5mm jack is not staying in place. Just to verify, has this been an issue since you first received the unit? Also, does this happen with multiple devices? Please let me know so we can look into this issue further. We appreciate your feedback!

Also, if you would like, I can assist you in setting up an RMA for a replacement. It appears as though the transmitter you received has a defective plug. We cover this product with a one year warranty and obtaining the replacement would be of no additional cost to you. If you wish to proceed with the RMA, just let me know and I can get that started right away. My apologies for the trouble and I hope this helps!

Gabby V.
Tech Support Associate
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FM Transmitter w/ Optional Charging USB Port (10403)

  • Vic,
  •  Falls Church, VA 
  • 1/5/2015 3:59:49 PM

Cons: 3.5mm jack does not fit in my phone because of the phone case.

Never got to try functionality because the phone case is a show stopper.

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