Review on 🚗 Nulaxy Bluetooth FM Transmitter: 1.8" Display Car Charger Adapter with Hands-Free Kit, QC3.0, 5V/2.4A, USB Drive, SD Card, Aux Input & Output - KM29 Grey by Ivan Carson

NULAXY latest update if you care at all you still hear the whistle after 30 minutes of use after various things since the warranty has expired i decided to split the cigarette lighter adapter case and throw one look inside. The first thing I found was the obvious cold solder joint where the cigarette lighter ground terminal is soldered to the circuit board. It was so bad I was able to pry the clip off the circuit board with my pinky finger. This is a large piece of metal that quickly dissipates heat during the soldering process. all of this together and THAT should have been the cause of the whistling problem. NOT RIGHT! Still whistling after about 30 minutes of use. Then I thought that some component in the head unit was overheating. I didn't want to break the body of the main unit so I decided to create some vents with a small hot nail to melt some of the vents into the plastic case. NO. still whistles after about 30 minutes of use and I've noticed it's a lot worse in hot weather. I finally found that the frequency of the whistling noise changes directly with the RPM of the tachometer. I highly doubt this is related to my jeep's electrical system as the KM29 runs fine for the first 30 minutes or so. And my old KM18 showed the same whistle but to a much lesser extent. Didn't really notice until I tried using it again after my experience with the KM29. After re-soldering the cold solder joints, trying different flash drives, creating air vents and a shielded audio cable, I give up. the whistle is still there. I'll try another company's device, but they probably all use the same chipset and similar circuitry. There may be a defective or misspecified component that is heat sensitive or needs better protection or noise filtering. Too bad the KM29 has all the inputs and outputs I need, easy to use, large display, large control buttons and fantastic sound for the first 30 minutes. -------------------------------------------------- -------- ---------- ----------------------- First a little background. The car is a 2K Jeep Cherokee with an OEM radio using the audio input. I only use the USB function. , have never used or needed the FM transmitter function. Upgrade from Nulaxy KM18. First the pros. This unit is much easier to use than my smaller KM18. The large display is easier to see and I particularly appreciate the large control button for my fat fingers. The sound is as good as it can get for an older car EXCEPT. Read below. Now for the cons. A white vertical bar appeared on the display of the first device after a few days of use. At the time this wasn't a major issue as I used to have to return defective products and will likely need to return again in the future. Revain quickly sent a replacement within days. Thanks Revain for the quick fix! Now to the second and current device. When I first tried the KM29 I had high hopes for the ergonomic improvements over my KM18. The first problem is using a mini USB stick with MP3 music folders and the included audio cable. Everything seemed to work fine at first, great music quality, easy to read display and large control buttons. Then, after about half an hour of music playing, a high-pitched "whistle" could be heard coming from the speakers. Over time, the whistling got louder until listening to the music became unbearable. Here is the signal to noise ratio. It is interesting to note that high-frequency noise appeared when the engine accelerated sharply. The stronger the acceleration, the louder the noise. It's not ignition EMI because the frequency of the noise is too high, I would estimate between 2 and 4 kHz. At this point, I'm assuming the EMI noise is coming from the electronic tach, speedometer, or stock dash. OBD-II connector under the dashboard. Or it could be generator noise coming through the 12 volt cigarette lighter, but I doubt it. Don't give up, the first thing I tried was another large flash drive. This seemed to improve things by reducing noise by maybe 20%. However, the longer the device played music, the louder the acceleration noise got, but not as loud as a mini stick. The next thing I tried was ordering a shielded audio cable through Revain. With a larger USB stick and a shielded cable, the noise during acceleration was reduced by, I would say, 90%, but it was still weak in the rest between song changes, but at least tolerable. Even when the first device worked, it had the same noise problem. Without saying that this will also happen to other vehicles, your noise level may vary. But these things are designed to work with older cars. Next comes a random function. I don't know what algorithm Nulaxy uses, but it's garbage. He tends to play the same song several songs later. Update: Now that I've been using this device for some time, the shuffle feature tends to play songs in the same folder from time to time. This random function is not true shuffling as far as I can tell. up, it should be a real shuffle and not random with randomly played songs. Update: Another annoying issue: when an EQ parameter is selected, the EQ parameter is NOT saved in memory for the next power up. gooseneck. I think because of the heavier weight of the head, the gooseneck doesn't support it. My KM18 lighter had no such problem. Update: As mentioned, I used a full-size flash drive to reduce high-frequency noise during heavy acceleration. It worked a bit, but the heavier flash drive added to the sagging of the gooseneck. Improvements I would like to see. - Possibly ventilation slots in the head unit. As mentioned, the noise gets louder the longer the device is on. Perhaps a larger display consumes more power. and dissipates more heat than smaller displays. And this constantly displayed mute audio frequency does not help the heat dissipation problem. - Full EMI shielding including main unit, gooseneck and cigarette lighter adapter. - High frequency filtering of the DC power supply. - Shielded audio cable. This, combined with a large flash drive, greatly improved the noise problem. The included audio cable is rubbish, at least in my situation. - Stronger gooseneck to support a larger main unit. - Recycle this audio frequency display or at least make it an option for those who like it. Instead, display more and more lyric information about the song currently playing. Or, even if it's a small display, at least give an opportunity for album art.