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I often lose reception on the car radio when I plug my smartphone into
the USB charger in the power socket provided.
Any workarounds? It's a nuisance on a long trip when I've got the
smartphone satnav on.
I often lose reception on the car radio when I plug my smartphone into
the USB charger in the power socket provided.
Any workarounds? It's a nuisance on a long trip when I've got the
smartphone satnav on.
I often lose reception on the car radio when I plug my smartphone into
the USB charger in the power socket provided.
Any workarounds? It's a nuisance on a long trip when I've got the
smartphone satnav on.
I often lose reception on the car radio when I plug my smartphone into
the USB charger in the power socket provided.
Any workarounds? It's a nuisance on a long trip when I've got the
smartphone satnav on.
On 10/10/2025 12:34, AnthonyL wrote:
I often lose reception on the car radio when I plug my smartphone into
the USB charger in the power socket provided.
Any workarounds?-a It's a nuisance on a long trip when I've got the
smartphone satnav on.
This is clearly atypical behaviour, so it may be specific to yourRF is a crazy bitch. All sorts of things affect reception especially if
particular car or phone.-a You may get non-generic responses if you
mention those.
On Fri, 10 Oct 2025 11:34:32 GMT, nospam@please.invalid (AnthonyL)
wrote:
I often lose reception on the car radio when I plug my smartphone into
the USB charger in the power socket provided.
Any workarounds? It's a nuisance on a long trip when I've got the
smartphone satnav on.
What about using a powerbank instead?
On 10/10/2025 12:54, Scott wrote:
On Fri, 10 Oct 2025 11:34:32 GMT, nospam@please.invalid (AnthonyL)
wrote:
I often lose reception on the car radio when I plug my smartphone into
the USB charger in the power socket provided.
Any workarounds? It's a nuisance on a long trip when I've got the
smartphone satnav on.
What about using a powerbank instead?
+1. Probably the simplest approach & not too expensive.
Sam Plusnet <not@home.com> wrote:
On 10/10/2025 12:54, Scott wrote:
On Fri, 10 Oct 2025 11:34:32 GMT, nospam@please.invalid (AnthonyL)
wrote:
I often lose reception on the car radio when I plug my smartphone into >>>> the USB charger in the power socket provided.
Any workarounds? It's a nuisance on a long trip when I've got the
smartphone satnav on.
What about using a powerbank instead?
+1. Probably the simplest approach & not too expensive.
A powerbank will rule out the car, but it won't rule out the phone or the charging cable. It's possible the SMPSU in the phone is the source of the noise, potentially radiated by the cable. It's a good test nonetheless.
On 10/10/2025 20:39, Theo wrote:
Sam Plusnet <not@home.com> wrote:
On 10/10/2025 12:54, Scott wrote:
On Fri, 10 Oct 2025 11:34:32 GMT, nospam@please.invalid (AnthonyL)
wrote:
I often lose reception on the car radio when I plug my smartphone into >>>> the USB charger in the power socket provided.
Any workarounds? It's a nuisance on a long trip when I've got the
smartphone satnav on.
What about using a powerbank instead?
+1. Probably the simplest approach & not too expensive.
A powerbank will rule out the car, but it won't rule out the phone or the charging cable. It's possible the SMPSU in the phone is the source of the noise, potentially radiated by the cable. It's a good test nonetheless.
The phone has an internal SMPS? What is its purpose?
Jeff Layman <Jeff@invalid.invalid> wrote:
On 10/10/2025 20:39, Theo wrote:
Sam Plusnet <not@home.com> wrote:
On 10/10/2025 12:54, Scott wrote:
On Fri, 10 Oct 2025 11:34:32 GMT, nospam@please.invalid (AnthonyL)
wrote:
I often lose reception on the car radio when I plug my smartphone into >>>>>> the USB charger in the power socket provided.
Any workarounds? It's a nuisance on a long trip when I've got the >>>>>> smartphone satnav on.
What about using a powerbank instead?
+1. Probably the simplest approach & not too expensive.
A powerbank will rule out the car, but it won't rule out the phone or the >>> charging cable. It's possible the SMPSU in the phone is the source of the >>> noise, potentially radiated by the cable. It's a good test nonetheless.
The phone has an internal SMPS? What is its purpose?
Many SMPSes. It charges the lithium cell from the USB input (which could be 5/9/12/15/20V based on the USB power delivery standard). There are also multiple voltage rails inside the phone that are all generated by SMPSes
from the battery voltage.
They're all switching so potential sources of RF interference. Additionally touch screens use RF to detect fingers, which can be another source of--
noise.
The phone has an internal SMPS? What is its purpose?
I thought they were just transformerless regulator circuits, and
didn't know there were such things as surface-mount transformers (<https://www.coilcraft.com/en-us/products/transformers/power-transformers/isolation/mini/>).
Couldn't find any specific refs to internal cellphone SMPSs, though.
Do you know of any?
On 11/10/2025 08:32, Jeff Layman wrote:
I thought they were just transformerless regulator circuits, and
didn't know there were such things as surface-mount transformers
(<https://www.coilcraft.com/en-us/products/transformers/power-transformers/isolation/mini/>).
Need not be a transformer. A simple inductor will do.
Couldn't find any specific refs to internal cellphone SMPSs, though.
Do you know of any?
Not specific to cellphones. All electronics today uses them
e.g. https://www.ti.com/lit/ds/symlink/tps61322.pdf
A typical laptop will have half a dozen
E.g. A raspberry Pi RP2040 chip requires 1.8v and 3.3V and the power
source is typically up to 5,5V
On 11/10/2025 10:44, The Natural Philosopher wrote:
On 11/10/2025 08:32, Jeff Layman wrote:
I thought they were just transformerless regulator circuits, and
didn't know there were such things as surface-mount transformers
(<https://www.coilcraft.com/en-us/products/transformers/power-transformers/isolation/mini/>).
Need not be a transformer. A simple inductor will do.
Couldn't find any specific refs to internal cellphone SMPSs, though.
Do you know of any?
Not specific to cellphones. All electronics today uses them
e.g. https://www.ti.com/lit/ds/symlink/tps61322.pdf
A typical laptop will have half a dozen
E.g. A raspberry Pi RP2040 chip requires 1.8v and 3.3V and the power
source is typically up to 5,5V
It was more the size of the transformer or inductor which was the issue
for a mobile phone. The smallest one in the ref I gave had a height of
5.46 mm. Add that to the board it's fixed to, the LCD screen thickness,
and the back of the phone case thickness, and with many phones only
around 9mm in height, it doesn't leave much room.
I often lose reception on the car radio when I plug my smartphone into
the USB charger in the power socket provided.
Any workarounds? It's a nuisance on a long trip when I've got the
smartphone satnav on.
On Fri, 10/10/2025 7:34 AM, AnthonyL wrote:
I often lose reception on the car radio when I plug my smartphone into
the USB charger in the power socket provided.
Any workarounds? It's a nuisance on a long trip when I've got the
smartphone satnav on.
There are a couple kinds of sockets in cars.
Legacy Battery ---- 25A ---------- Lighter --- Spring-loaded
Fuse Socket Lighter Element
Modern Battery --- fuse --- SMPS ---------- Precise voltage outlet #1 >(Accessory ---------- Precise voltage outlet #2
outlet)
The SMPS, if you draw current from it, is likely to make some
RF interference while doing so.
If you were doing this, and had an external buck converter
feeding the phone
14.4v 5V
Legacy Battery ---- 25A ---------- Lighter ------ Buck Converter ------- Phone
Fuse Socket
then the Buck Converter (a type of SMPS) could be making the
electrical interference.
*******
One test you can try:
12.000V
Modern Battery --- fuse --- SMPS ---------- Halogen 12V 1A bulb ---- GND >(Accessory
outlet)
If every time you plug in a halogen bulb into the accessory outlet,
the radio is suppressed, then it is the in-car SMPS doing that. When
the halogen bulb is cold, it can draw more than 2 amps, but once it
heats up, the power drawn will drop to the "rated current value",
like 1 ampere. You would not want to use a 12V LED bulb, because
the bulb might have an SMPS inside it. The Halogen bulb does not
generate interference.
The reason we are starting with this part of the analysis, is
to determine whether there is any *easy* way to fix this.
If the in-car SMPS is buried somewhere, or it powers other
parts of the car, you can't be playing with it.
If you determine you have a legacy design, and the socket has
14.4V while you are driving, then you might consider a two stage
linear regulator. It wastes power like crazy (10W loss first
stage, 8W loss second stage, 18W total heat), but a linear
regulator is quiet and won't upset the radio. But if the
linear regulator is drawing power from the in-car SMPS,
then the SMPS will continue to pollute the airwaves with
RF noises.
There are SMPS all over the place, and we have to make sure
the noisy ones are not being used.
If you place an auxiliary automotive battery on the floor of
the car, next to you while driving, that battery can be a
source of quiet power. You can then experiment with various
converter types, and see if it is possible to make something
work. The battery may last for some short trips, but might
not be good enough for a 16 hour drive. And your converter
should have a low-batt feature, so it does not drain the
auxiliary battery below about 11V. Automotive batteries
(not Leisure batteries), do not like being discharged
all that much. You can't be draining them to 6V on each
trip, and expect to get a lot of charge cycles from the
thing.