Questions tagged [automotive]

Questions about the design of electronics for use in an automotive environment. (Questions about the installation and use of automotive electronics are unlikely to be appropriate for this site.)

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88
votes
10answers
293k views

Why does a Tesla car use an AC motor instead of a DC one?

I was just watching a mega factory video and wondered why they use an AC motor which requires a power inverter instead of DC which may be powered directly from their DC battery? Introducing an ...
15
votes
4answers
5k views

Protection against automotive power supply hazards

I'm looking for a way to protect a small circuit which is to be used inside of a car or truck (12V or 24V power system). The circuit consumes about 12-15W. I use an isolated DC/DC converter module ...
7
votes
3answers
18k views

Detect car +12V using Arduino

I am looking to detect 12+V from a car wire using an Arduino. I have found the following schematic: I know how crazy automotive voltage can get so I just want to make sure the schematic I found ...
9
votes
2answers
15k views

How do I protect against an automotive load dump?

A load dump occurs when the load to which a generator is delivering current is abruptly disconnected. In automotive electronics, this applies to disconnecting a battery while it is being charged by ...
2
votes
3answers
2k views

Car bluetooth power delay- USB capacitor? [closed]

I just bought a bluetooth adapter for my car. It's input is 5V/0.3A and is powered via a 5V/1A USB power adaptor that is plugged into the 12V/10A/120W max. socket in the center console of my 2004 ...
3
votes
4answers
6k views

Combining RFID badges

I have multiple RFID cards that I use to get into parking garages at the office, client site, home, parents place, etc, etc, etc..... I'd like to either A) combine all of these into 1 card or ...
2
votes
2answers
6k views

How to calculate bus load of CAN bus?

I have a few questions regarding CAN bus load Is there any derived equation/formula to calculate the bus load? I need transmit below frames(Assume Standard frame format) at baud rate 500 kbps on the ...
39
votes
3answers
198k views

Why do we connect a battery to ground when jumping a car?

This may seem like a very simple question, but I've searched all over the place and haven't found an answer. When jumping a car, we connect the + end of the charged battery to the + end of the dead ...
58
votes
8answers
16k views

Why are there so many relays used in a car, instead of transistors?

Recently I did some work on my car electric circuits. I see many relays are used in car circuits. These relays are used for simple switching, and I wonder why these circuits are based on relays and ...
6
votes
1answer
21k views

Why is there risk of overvoltage when jump-starting a vehicle?

Ford Focus C-Max manual describes jump-starting procedure as follows: shut off everything, connect the jump cables, start the donor vehicle engine and let it run for a while, turn the ignition key on ...
26
votes
1answer
150k views

What is the polarity of a car cigarette lighter adapter?

There is a center pin, and two outside tabs. Which are positive and negative?
4
votes
2answers
3k views

Automotive electrical system. How does everything work?

I recently grew a big interest into the electronic world. I also love auto/mechanics, and I’m trying to understand where these two wonderful areas meet. I’m trying to understand the fundamentals of ...
0
votes
1answer
1k views

current/voltage isolators in cars

When I attach something sensitive like a analog camera and LCD screen to a car battery along with a switched high amp load like a power door lock actuator, I get video problems when the load is ...
0
votes
2answers
2k views

Sense Automotive 12V Circuit from 3.3V microcontroller safely

I want to sense a circuit state in an Automotive circuit (12V nominal) from a 3.3V microcontroller (MSP430Gxxxx). The circuit is normally 12V (or VBat) until either the Wireless ECU or a Door Key ...
5
votes
2answers
7k views

Why do PTC fuses have different voltage ratings depending on package size / hold current?

I've been trying to figure out the PTC fuse I want to use in a little automotive power supply circuit and I'm a little disconcerted by the max Vdc ratings most of these things have. For instance, ...
1
vote
2answers
293 views

What would happen if I choose a connector with current rating smaller than the actual current?

I need a butt splice connector that can handle up to 150A, which is really hard to find. What would happen if I connect it to a 12-10AWG butt splice connector? Other type of connectors are not ...
80
votes
6answers
11k views

Will radar/lidar still work when every car is equipped with them?

Self driving cars rely on cameras, radar, and lidar to recognize the environment around them. Cameras of course don't interfere with each other, since they are passive sensors. Since a signal ...
18
votes
5answers
13k views

Tesla Car “maximum torque at 0 RPM” - is this correct?

Tesla Model S Wiki I've been watching youtube videos on this car, and everyone states that the crazy accelleration is due to maximum torque at 0 rpm. Doing further research, this car uses an AC ...
8
votes
2answers
3k views

Automotive power filtering, protection - feedback needed

I'm working on GPS tracker for automotive applications. Device should work in 9V-30V supply voltage range. In practice it will be fed from 12V car installation. This enforces the implementation of ...
11
votes
1answer
3k views

Simulating an automotive load dump with a bank of charged capacitors?

I've been working on a data logging device that will eventually go into my personal vehicle. I've scoured the interwebs and built what, in theory, should be a fairly stout power supply capable to ...
3
votes
2answers
6k views

Relay for Intermittent Wiper Function

I want to add an intermittent function to the wipers on my 40-year-old car without any additional switches. The details of the wipers can be found here [http://www.globalsoftware-inc.com/coolerman/...
14
votes
3answers
7k views

Arduino in car: capacitor for extra 3 sec of power

I want to install an Arduino Uno in a car, powered by a consumer 12V->5V car voltage regulator plugged into the lighter socket. The socket is switched, i.e, there's no power when the motor's off. When ...
7
votes
3answers
20k views

Splitting wires for newbies

I'm in the process of getting ready to build a car PC running Linux. One of the features I'd really like to incorporate is the ability to record car statistics from the sensors live using ODB2. Due ...
6
votes
3answers
53k views

Is it okay to keep a USB charger plugged into the cigar lighter?

I have a USB micro charging adapter for my smartphone for my car. It is basically a cigar lighter plug that turns into a USB micro plug. When I don’t have my phone connected, and as such don’t want ...
5
votes
1answer
1k views

Converting a tachometer signal into something a microprocessor can understand

I am attempting to build a digital dashboard for my car (a 1998 honda civic), I have run into a bit of trouble, wherein the tachometer signal is quite hairy. I was wondering if someone would lend me a ...
8
votes
1answer
2k views

How can I simulate and handle an automotive load dump?

Long story short, I'm designing a little device to monitor a sensor or two in my car. I'm not an EE, but I'm a stickler for knowing things will work right and that I won't have wasted my time and ...
3
votes
1answer
722 views

How can CAN transceivers ouput CANH=3.5V and CANL=1.5V?

When sending a dominant bit (0bit) on the CAN bus, I understand that CAN transceivers output CANH=3.5V and CANL=1.5V. But when looking at the schematics of a CAN transceiver, I do not understand how ...
3
votes
7answers
2k views

Opinions on what I've come up with for a 12 V-to-5 V automotive circuit?

Is this a solid solution for an automotive 12 V-to-5 V circuit to power an ATtiny? I've been trying to come up with a solution for my needs that can handle the automotive environment that is so scary ...
2
votes
1answer
5k views

Jump start car from lithium ion laptop battery

Building the actual circuits is beyond me at this point, but I'm wondering if it's technically possible to jump start a car from the power contained in a large lithium-ion laptop battery. For example,...
1
vote
1answer
1k views

Why is the CAN bus always busy (microcontroller)?

I'm trying without success to perform CAN bus communication between an microcontroller and the host (my computer). My question does not depend on the microcontroller, but on the CAN Bus (classic CAN). ...
1
vote
2answers
4k views

How to switch between two DC power sources powering a motor on an electric vehicle?

Background: For a university final project, my student group is investigating the possiblility of powering a motorcycle with two seperate batteries, each of a different chemistry (Lead-acid and ...
1
vote
2answers
143 views

First Time Using Integrated Circuits

I am building a circuit for a custom application. I have an old Toyota truck, and I keep leaving the headlights on, because there is no warning buzzer! I have designed a circuit that takes 3 inputs: *...
1
vote
2answers
146 views

Need a circuit to detect if something has gone from off-on or on-off

I'm new to circuit design but I'm trying to design a circuit for a power antenna that will send a 5 second pulse whenever it detects a a wire has gone from off-on or on-off. So far I have designed ...
0
votes
3answers
2k views

Alternator current when charging flat battery

I've found some voltage-current-rpm graphs for car alternators and did not quite understand one thing. Basically, my alternator is rated at 75A (small car), which it should output above 2000 RPM or so....
5
votes
4answers
699 views

Does anybody recognize this automotive connector?

I'm trying to repair a wiring harness, and I'd rather pin and install a connector than splice into a junkyard pigtail. Does anyone recognize this and know where to find them? There's some serious ...
5
votes
4answers
417 views

Industrial electronics layout and design

Why do industrial panels for oil and natural gas compressors or other industrial equipment use terminal blocks for wire management? I have been doing some repairs for companies and was wondering why ...
3
votes
2answers
5k views

OBD port power source [closed]

I've read on forums that OBD port can provide max 5A current at 12V. What is the source of the power? Is it coming from battery directly or is it regulated power supply from somewhere else, maybe ECU? ...
3
votes
2answers
497 views

Possible to reliably run USB over a non-standard USB cable?

I'm planning on building a device for my car that sits somewhere in the rain tray or behind the dashboard. It will use automotive connectors so that things are sealed, easily connected and ...
3
votes
1answer
892 views

Switch from electolytic to ceramic capacitors in car ECU?

I'm looking into replacing the capacitors in the vehicles ECU. I know the ratings and voltages for the three. My question though is which would be better to go with, electrolytic or ceramic. I'm not ...
2
votes
1answer
203 views

Powering Atmega, DAC and Bluetooth in Car

I'm looking for a proper power supply schematic which would fit my needs and would have all required protections (overcurrent, overvoltage, reverse current, etc) for use in car. I want to power Atmega ...
2
votes
6answers
4k views

Electronic flasher with low load detection

The circuit above is an existing flasher without low load detection. I am trying to develop electronic 2-wheeler flasher with low load detection. While Googling, I got a circuit with relay in it, one ...
2
votes
2answers
229 views

What to look in a desktop/small DC Power Supply?

I'm looking for the most adequate power supply that can go between ~0-30v and ~0-5A. These are going to be used for software development for automotive infotainment systems and the operation specs for ...
1
vote
2answers
411 views

Using a PIC to perform switch on and timed shutdowns in automotive environment

I would like to build a circuit to perform a timed shutdown, based on logic inputs from headlamp wires and ignition wires. I have decided on PIC10F200 (datasheet) to perform the logic. I also have ...
1
vote
1answer
165 views

Spec'ing an always-on alarm/tracker for a car battery

What is the specification of a standard car battery (e.g. of a 2008 Jetta)? Say, I want to connect an always-on alarm or a tracker to the electrical system of the car. Is it likely to deplete the ...
1
vote
1answer
53 views

DC1601B Demo board input line caught fire during use

I am using a DC1601B-C buck-boost converter in an automotive circuit to power some various electronics that I have added. It worked fine for a couple months, but under a less-than-normal load of 2.25A ...
1
vote
1answer
151 views

Powering a Behringer MicroMIX MX400 - Car Audio Application [closed]

I am installing a car audio system that will have TWO aux inputs; one in the dash and one in the rear passanger seat are. I decided to purchase the Behringer MicroMIX MX400 mixer. The power spec for ...
1
vote
4answers
207 views

CAN bus communication mechanism

Does every node on a CAN bus just keep transmitting data no matter what or does it only transmit data when it is "requested" to by other nodes on the same bus?
0
votes
3answers
261 views

Can I use this analog switch for CAN bus signals?

In the deutsch 9 pin obd interface for heavy trucks, some manufacturers use the pin F,G for J1939 protocol and some use it for J1708 protocol. I am trying to use a NLAS4684 analog switch with dual ...
0
votes
1answer
550 views

Mysterious Noise Issue in Automotive Ignition Coil Application, Arduino

I'm building a circuit to count RPM based on watching the negative pole of the primary coil in an old automotive ignition coil. I had no illusions this would be easy, but here I am stuck even though I ...
0
votes
0answers
131 views

Transformer Welfare

I know this circuit is dangerous, but i made it anyway (probably a mistake)-https://www.instructables.com/id/Variable-voltage-ignition-coil-power-supply/ In my circuit, I used a small ignition coil ...