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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56 views

How to find RPM from the square wave of a MSD box

I am trying to make a tachometer for my car. I am using a MSD6Al-2. The box outputs a 12 volt square wave at a 20 % duty cycle I talked to someone at MSD and they said you'll get a signal every time ...
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57 views

Approach to prevent Replay and spoofing attack on CAN protocol

I want to make an authentication system between 2 buses. In order to achieve that I use counter to avoid replay and hash to avoid spoof. The message must be sent in two phases. Is there any proper way ...
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1answer
34 views

How can I add a raspberry to a touchscreen car dvd unit? [closed]

I am working on converting a Toyota 2-din touch screen dvd stereo unit into a car computer. I would like to add a raspberry to it and be able to have the raspberry display a browser on the touch ...
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72 views

Automotive 3.3 volt supply that can survive engine start

I am powering a PIC32MX microchip using a 3.3V Linear Regulator (LM2937), supplied from an RBO40 which I fitted in an effort to protect against adverse conditions such as load dump. As an aside, I've ...
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1answer
37 views

15A 125V smart plug being used to slow charge electric car [closed]

So my car is using a charger that from what I'm told is both level 1 and level 2 capable. What I'm getting from the car is that its slowly drawing 8A continuously untill charged. The plug I have in ...
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74 views

How to power bulbs expecting 24V AC from a car's “cigarrete” socket?

I'm turning the trunk of my car into a UV-sanitizer chamber -- so that, by the time I return from the supermarket, the bags and the packages handled by strangers there are sterile. To this end I ...
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22 views

Charging Electric car battery from solar panels using PV cells and Zappi charger

In the UK there is an ev car charger made by myenergi which uses solar panels to charge your car. The link to the product is below https://myenergi.com/product/zappi/ This product allows you to ...
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1answer
36 views

Transient Voltage Suppression Diode with no current limiting component

BATT= 16V 27V Rated TVS Diode spec - TVS Diode Datasheet The circuit : My questions: I want to understand what happens when the BATT voltage goes above the TVS diode clamping voltage. For both ...
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2answers
46 views

Measuring a 2-pin active wheel speed sensor without having it connected to a vehicle

I'm trying to measure/test the square wave output of an active wheel speed sensor from a jeep wrangler for a project I'm working on. I do not have access to the actual vehicle just the sensor itself ...
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1answer
94 views

12V PWM to Analog DC converter for car cooling fan

I’m installing two 12V 80W cooling fans in an old BMW which originally uses a PWM electric fan. This original fan has a three pin connector (constant 12v, ground and PWM signal from the ECU). I ...
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1answer
65 views

Can I wire these automotive peltier heating/cooling devices as on/off without a temperature controller?

I have an seat removed from a Lincoln MKX that I mounted using scrap wood and heavy casters to use as an office chair that has power adjustment as well as Peltier heating/cooling components in the ...
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37 views

ISO 7637 Supply Transient pulses - Explanation

I am trying to design an input power supply filter circuit inorder to protect from ISO 7637 pulses. I am referring this Little fuse app note There seem to be different pulses. Pulse 1, 2a, 2b and so ...
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3answers
192 views

Why would one mount components above the PCB?

Inside of an automotive ECU I noticed that all three crystals are mounted about 1/4" above the PCB. What is the advantage of doing this versus mounting the case flush with the board? This seems like ...
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2answers
65 views

Thevenin Equivalence Problem

So I have this question that I'm struggling to understand and solve, it goes like this: I want to determine the Thevenin equivalent of my car battery. You measure a voltage of 12.2V across the ...
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3answers
121 views

Turning on an automotive relay when enough voltage is avaialble

I'm trying to drive a relay off a dome light in a car, where the dome light fades in smoothly. That is, say, I have a constant ground and the other wire goes from 0 to 12V (up to 14V) over a couple ...
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2answers
310 views

Why can one pour water on a car battery's terminals (12 Vdc) and not have shorting

When cleaning a standard 12 Vdc car battery's terminals, it's a common practice to pour a mixture of baking soda + hot water all over the terminals. The water can spread and effectively short out the ...
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3answers
509 views

Disconnect car battery with receiver [closed]

I have no clue what I'm doing but I want to prevent anything down the line of my car battery draining it, so I was thinking of somehow disconnecting everything down line while it is off. Pretty sure I ...
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2answers
52 views

Wire hangers under connector

I have noticed small hangers under the Rosenberg HSD connector: What is the purpose of these? I can only guess it's solder paste storage for pin-in-paste technology but on the other hand, it's quite ...
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3answers
50 views

Operate car lights using microprocessor and simplified wiring loom [closed]

I'm in the process of converting an old car from petrol to electric. Looking at the wiring loom (it's a mess!) each thing in the rear of the car has a +ve and -ve cable running from front to back. ...
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3answers
94 views

Are optocouplers enough of a protection to sensitive electronics

There are certain lines in my car which I want to detect when hot. My initial thought was to hook a voltage divider to drop from 12v (or ~14 rather) to 3.3 and feed it to my pi but I soon realized ...
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1answer
28 views

Stable dc voltage for raspberry pi connected with Truck power outlet

I have an IoT project with the raspberry pi as the microcontroller. Now my device connects with the power supply of a truck i.e. via the 24-volt cigarette lightning adapter. The device has few push ...
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1answer
73 views

LM393 output flickering?

simulate this circuit – Schematic created using CircuitLab I'm using this circuit to detect if a car engine is running. I tested it and it is working however there is some kind of a problem ...
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1answer
76 views

Need help sizing zener diodes and varistor for 12v automotive power supply protection

I have built an astable 555 timer circuit to control a MAC valve that will allow me to change the turbo charger boost levels on my S10. The circuit works great as is but I skimped out on the circuit ...
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1answer
39 views

Can I run 12V camper van fridge whilst 'trickle charging' the battery in van?

I am running the following setup in my camper van and would like to know if there is a simple solution or device that would be effective in allowing me to run my 12V fridge whilst the leisure battery ...
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0answers
50 views

Basic Question: Why does this Short cause Blown Fuse?

I recently re-did some wiring connections for the horns in my car and accidentally shorted the wires out at the green wire in the picture below. This causes the 20 Amp fuse to blow, but I do not ...
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2answers
226 views

Why does my transistor get hot?

I'm continuing development from this question. The schematic given by Jasen worked as a charm but little did I know that was with the connector plugged out, as soon as I plugged the connector in I ...
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1answer
55 views

Feedback on astable 555 timer circuit to control MAC valve for turbo control

I have some questions and wanted to get feedback on this circuit I have put together. Basically to see if there is something I missed or obvious that I should change or should have designed ...
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1answer
49 views

Fitting home made circuit on petrol scooter

I have an old honda scooter which has bulbs in all lights. Also, they are driven by AC voltage. I made sequential led indicator circuits(four of them) using 74HC595. The working voltage of the circuit ...
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3answers
184 views

Using very low voltage from dimmer switch to trigger 12 volt supply

I have a new stereo head unit in my car that auto dims when the headlights are on. The head unit does not have a variable dimmer, it is either on or off. I have a dimmer switch in my car that is ...
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1answer
41 views

Necessity of an Inductor at CAN Transceiver end

Basically 120 ohm of resistor needs to be connected as terminator resistor at the end of the physical CAN channel. My question is that here, what is the necessity of an inductor (L310) between CAN ...
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1answer
58 views

Driving car electrical vacuum pump

I am trying to drive an electrical vacuum pump from a car directly from 12 VDC. Earlier, I succeeded with a different pump just by connecting them to DC power, the other pump (different brand) used ...
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1answer
48 views

Sniffing lowspeed CAN bus with highspeed device

Is it possible to use a highspeed (HS) CAN interface for listening to a lowspeed (LS) CAN bus? If so - Is it in any way questionable to do so in a real world car or moped? As far as I know, LS CAN ...
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1answer
152 views

Confusion in transistor circuit

I'm hacking my car's locking system, I want to be able to lock/unlock using a MC and ultimately my phone. I've spliced the connector and after a quick inspection I located the 3 pins that do just that,...
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0answers
160 views

LIN bus sniffing with Arduino

I'm trying to do a simple LIN bus sniffing in my car with an Arduino. This should be possible with a simple voltage divider if I'm not wrong. Would this schematic work? ...
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1answer
53 views

Which cell balancing method is best to use and implement for low-voltage (48V battery stack) battery management system for E-bike application? [duplicate]

I would like to design a battery management system for low voltage systems. I am developing a BMS for a 48V, 20Ah battery pack system. When it comes to battery balancing, I am confused in between ...
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1answer
129 views

PNP transistor switching and inductive load

I am designing a circuit to control a motorcycle horn (its operating frequency is 490 Hz, its resistance is 3 Ohm, and it consumes 1A on average as indicated by the power supply), and LED lights. The ...
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1answer
74 views

Defect LED detection for car lights

The schematic beneath is a new project of me. The theory behind this is: My car has a very fool proof bulb failure detection and warning system. CANbus proof LED bulbs can't fool the car and just a ...
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3answers
235 views

Latching Relay That Follows +12VDC Trigger and Uses No Power Unless Switching

I have an application where I have a +12VDC circuit that I need to use as a trigger for a latching relay. So, when +12VDC is present, the relay would SET. When +12VDC is not present, the relay would ...
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63 views

reversing behavior oh NC switch (for dummies)

i'm wondering if i can use a NC switch for courtesy light of my toyota, At the same time as NO switch for a device called "sterring auto tilt" when you enter the key you clik a switch that allow the ...
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1answer
56 views

Which cell balancing method (active or passive) is best for low-voltage BMS (Battery Management System)?

As a beginner, I am going to design and develop a BMS (Battery Management System) for low-voltage applications (electric bike). So I would like to know which cell balancing method is perfect for low-...
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2answers
82 views

Measuring continuity on a car battery while connected - damage?

If you were to put both leads on negative and positive terminals on car battery while connected and have the meter on continuity (the one which beeps), what happens and can it fry/ruin the electronics ...
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1answer
226 views

Car battery voltage readings different with no load - normal?

Typical car battery, 12V. While connected to the car, It read 12.38V on my multimeter. Using the absolutely same multimeter, I measured it once I disconnected it from the car - voltage went to 12.56V. ...
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3answers
1k views

What does it mean when my car inverter's labeling says “Neutral Floating”? Is it safe to use?

I recently came across a fairly old car inverter. It plugs into a 12v DC lighter socket, and outputs 115 Vac at 60 Hz, and has a normal American outlet on the side of it (with a ground pin, which ...
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0answers
25 views

Is it risky to use a non-isolated step-up CV/CC controller as a battery charger in a van?

I want to use my van's 14V alternator output to charge the 24V lithium (LTO) house battery. Commercially available devices come with bells and whistles for all kinds of lead batteries that I don't ...
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2answers
1k views

Electronic Controller Unit (ECU) Vs. MCU

Isn't the Electronic Controller Unit (which are used in automotive applications) a Microcontroller it self? What is the difference between them in architectural point of view?
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1answer
61 views

Interfacing LIN bus with CAN

On the following figure, LIN is used to build subnetworks from a CAN bus: Is there any standardized way to interface these two buses (e.g. for addressing a LIN node from a CAN node)? I read an ...
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0answers
112 views

Radio static caused by windscreen wipers

I was driving past a radio station transmitter of the radio station I was listening to. I turned on my windscreen wipers, which caused a noticeable static to be emitted through the speakers for the ...
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3answers
247 views

Can I replace a 12a fuse with a 15a fuse on a 12v - 120v automobile inverter?

I'm hard wiring an inverter into my automobile. Tapping into a 15a fuse in the fuse box. To hard wire it I had to remove the "cigarette plug" and in so doing removed a 12a fuse. I have an inline fuse ...
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0answers
49 views

Switchable Pullup (Automotive)

We are looking to add to a product software-controllable pullups on sensor signal lines. Currently the signal lines we hardwire to a pullup of 5V via a 2K7 resistor, but other systems allow software-...
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2answers
133 views

A question about practical use of ignition

As far as I understand, if I'm not wrong there is capacitor discharge ignition and inductive discharge ignition. Is the difference between two in one of them the current spike is drawn from battery ...

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