An application field of electronics that requires high reliability and fail-safe systems. Application can vary widely in temperature ranges and a wide voltage range, typically 12v (or 24v) while off and higher when on.

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Vintage electric car circuit problems

This circuit is in a vintage electric car. The 12 volt circuit works perfectly alone. The 36 volt circuit works perfectly alone. When both circuits are activated the contactor points bounce open and ...
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1answer
54 views

PIC operating temperature… “industrial” vs. “extended”

I am shopping for a PIC micro-controller for use in an automotive application. I noticed that PICs are offered in both "industrial" and "extended" temperature ranges ([-40C to +85C] vs [-40 to +125]). ...
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1answer
46 views

Car electronic accessories [on hold]

I want to design a computer vision device that will act as a "driving assistant". The device will improve driving safety by acoustically or visually alerting the driver of certain hazardous situations ...
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1answer
45 views

Arduino in Ground-Chassis (Vehicle): Activate by grounding

I am working with an Arduino as a controller for an Aftermarket Heated Seats Kit and interface for the stock A/C Auto Control Panel (the car did not come with heated seats, and I acquired an A/C Panel ...
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1answer
43 views

Single wire CAN // Saab 9-3 I-Bus // GMLAN

I'm trying to control an instrument cluster from a 2008 Saab 9-3. It has 2 pins marked for I-Bus (both wires are green, continuity test shows they are tied together as shown here: Some sites also ...
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1answer
39 views

LEDs not lighting up with reverse bulbs on my truck

Recently purchased the WSFS-NW180-BK LED Light strip from superbrightleds.com, but the LEDs are not lighting up in conjunction with my reverse bulbs. I spliced the LED positive wire with the Reverse ...
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2answers
48 views

Ignore voltage below threshold

I am trying to detect the presence of +12v on V2 to trigger a digital pin on a micro controller. I am using an opto isolator as I am under the impression that it is the best way to isolate my ...
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2answers
84 views

Using LiFePO4 battery as car battery

I've had an idea of using LiFePO4 battery as replacement for car battery, since 4 of those in series make nominal 12.8V which is very close to standard 12V voltage. And depending on the cell we can ...
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97 views

PNP BJT as a 'switchable' flyback diode?

I have an automotive ignition coil which I'm using as an ignition source for a project I'm working on. During normal operation, the primary coil current will be interrupted periodically to induce ...
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1answer
71 views

Grounding for car stereo adapter PCB

I've built an audio adapter for car stereo system. It contains microcontroller, a connector to stereo system (a few data pins and line-level audio output), Bluetooth audio module (RN52) and power ...
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1answer
75 views

Bipolar stepper motor (Alfa Romeo 156 speedo) w/ L293D

I would like to use my Alfa Romeo speedo in my simrig, I have got the cluster pinout and the speed signal is coming from the ABS (Just like any other car, my BMW cluster works like charm). The only ...
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0answers
47 views

Why does ignition coil have polarity markings?

I know about one reasonable answer to this. The electron emission is easier from a hotter surface, which in a spark plug happens to be the central electrode. So we should connect this electrode to be ...
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1answer
71 views

Sequential Taillight Modification

I am interested in almost duplicating the functionality of the new Mustangs. When the rear tail lights are activated (there are 3 in a row on each side), I'd like the first one, then the second one, ...
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1answer
85 views

LED strip segments Parallel vs Serial

I have 5050 RGB LED Strip and an RGB controller (Something like this ...
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1answer
147 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 ...
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6answers
1k views

Why is the chassis used as ground in automotive electrical circuits

Automotive electronics generally use the metal chassis as the negative ground connector for the DC circuits. Obviously this saves something on wiring. Is there an electrical reason for this approach? ...
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0answers
46 views

How to measure RF receiver

I am trying to check how electric devices such as Sunroof could affect the remote key performance range (meter) for cars. I am thinking of measuring relative antenna gain of RF receiver of one test ...
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0answers
83 views

Why are AC induction engines for electric cars so expensive?

I was reading about electric car engines and from what I've read there are 2 types available, DC brussless or AC induction ones. Each has its advantages and disadvantages but it seems the AC induction ...
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2answers
945 views

Why don't we get shocked when we touch a car?

According to this answer to a question about car batteries: [...] so the entire chassis is an extension of the minus terminal of the battery. If this is the case, I would expect that you'd get ...
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1answer
56 views

Simulating a load dump circuit [duplicate]

I am trying to build automotive load dump circuitry to bench test my inverter design. I would like to know if anyone has any experience building something like this. I need to create a 172V spike that ...
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2answers
88 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 ...
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1answer
60 views

Trigger Relay Only from one specific grounding path?

I have a car wireless door lock system I want to modify. The basic operation is that when the key fob's button is pressed, a light relay is triggered, to flash some of the car's lights, to indicate ...
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1answer
38 views

Precise Measurement of Noisy Voltage

I'm working on a circuit that will have a current shunt before a device connected to a truck's 12V system. This system can have voltage drift, and large transients during operation. The connected ...
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1answer
82 views

Automotive Sensor - Excessive Ripple Noise

I'm designing an automotive oil temperature sensor based around a 3-wire RTD. This is my analog circuitry: U1 and U2 provide a 1mA bias on the RTD which is measured by U3 and gained up by U4. R5, ...
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2answers
143 views

Slowing Down Capacitor Circuit discharge rate

I am currently trying to use a 5 Pin relay on a Motorcycle indicator circuit. The concept is I have a Daytime Running Light (DRL) that is in the same housing as the indicator. When the indicator is ...
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1answer
76 views

electrical fridge running on car battery [closed]

I'll be out of grid for some days and I'm planning to have a small electrical fridge with me. It's a 12V 4A small fridge with a cigar lighter plug, but I won't have a car with me, so I think I could ...
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1answer
50 views

Taking power from two different feeds

Probably a silly question I know but I'm not all that good when it comes to wiring but at the same time don't want to blow myself, or my car up! I have a set of sidelights/ daytime lights that take a ...
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2answers
91 views

Control automotive AC switch via TPS voltage

The A/C compressor is engaged via a single wire that comes from the 'A/C' button on the dash board. I want the A/C button to disengage when the throttle is at 50%. The throttle position sensor (TPS) ...
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1answer
121 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 ...
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2answers
388 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 ...
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1answer
64 views

Sense existing vehicle TPS with AVR ADC

I have an issue sensing the throttle position sensor voltage if the sensor is already being used by the vehicle's own ECM. Namely, the vehicle ECM stops responding to the throttle input after a period ...
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1answer
64 views

Automotive IO input protection design for ESD, transients, and reverse polarity compatible with ISO 7637

I want to accept an signal that could have any of the transients defined in ISO 7637-3 on it. It is a reset signal that could be tied to 24V in the case of a wiring harness meltdown but typically ...
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1answer
90 views

Connect two-function brake light to three-function car circuit

I need to replace my 12VDC (bulb based) brake lights but I am unable to find a three-function light (Running/Brake/Off) with the same specs. I did however find a two-function light LED fixture ...
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4answers
324 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, ...
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1answer
54 views

Is there any way to control a 12Vdc relay using 60Vdc line

I have a 60V li-ion battery back with PCM board attached to it for protection. According to the PCM datasheet, under fault condition the PCM cuts off the load and thus isolates the battery bank. The ...
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2answers
101 views

How should I understand this twin coil relay pinout? (Screenshot)

I'm currently looking on an automotive twin coil relay. The Datasheet gives me following schematic: My Question is: How could I test this relay? In other cases I put the corresponding Voltage on ...
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3answers
89 views

RGB LEDs in automotive environment with fluctuating voltage

I'm hooking up an Arduino to an automotive power supply which fluctuates between 12 and 14.4 volts. I'm also hooking up RGB LED light strips in this circuit as well, now I'm not afraid of the 14V ...
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1answer
112 views

Does it matter if I shield the antenna wire or the interference source

I have a problem. My car radio is picking up interference when ever I plug a device into the power outlet/ cig lighter. I know that the solution would be to put shielding around the antenna wire, but ...
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303 views

Does AEC-Q101 Certification mean a part has some ESD protection?

I'm working on picking out some FETs and would like to use some with ESD protection. While picking some parts out on Digikey I keep coming across datasheets that say AEC-Q101 compliant or sometimes ...
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0answers
303 views

Android CAN bus connectivity via Bluetooth (or USB) [closed]

I'd like to read sensor data from existing CAN buses using a bluetooth (preferably, though USB would also work) device of some sort. Trouble is, I've never done CAN bus, bluetooth or android ...
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3answers
1k views

How do the streetcars in Toronto draw power from the lines?

I've tried googling this but to no avail. I've been trying to figure out how streetcars can draw power from a short circuit. For reference: If I imagine the power lines simplified as a shorted ...
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2answers
157 views

12v capacitor / UPS system [duplicate]

I am looking to make a capacitor/UPS system for a few different electrical components in my car. I want to power the rear view camera, headrest monitors, and possibly the head unit for about 30 ...
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1answer
202 views

Detecting vehicle on parking spot

For a project we're working on we need to detect if a car is standing on a parking spot. We're using an ultrasonic sensor for this, SRF05. While using the correct timings we can only sense for about a ...
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0answers
26 views

Troubleshooting my antenna power delay

Awhile ago I build a circuit to fool my power antenna into sensing a constant voltage while I started my car. enter link description here It worked great. So installed a new power antenna and ...
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2answers
102 views

Automotive Logic Signal Switching and ESD/transient susceptibility

Sorry...can't think of a succinct question for the subject line! I am working on a project on my car. The car's existing ECU is connected to a pressure switch, which opens when the A/C refrigerant ...
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1answer
832 views

What do chips like ELM327 and STN1110 do?

What problems are the chips ELM327 and STN1110 solving? If I connect the necessary interface ICs (I mean dumb ICs, like level shifters, inverters, etc., not pre-programmed devices like ELM327) ...
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2answers
260 views

Combine two audio signals

I'm currently building an in-car alert system using a Raspberry Pi. My car has an AUX port (3.5mm jack) which I currently use with my phone - to play music. I wish to be able to play music, and play ...
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1answer
118 views

What are the components used for the iPhone-sized car hack? [closed]

Recently two security researchers hacked a car with iPhone-sized gadget according to this link. They didn't release any technical details, but I think we can guess from the picture of the gadget: ...
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1answer
84 views

How Do Vehicle Backup Sensors Work?

How do the backup sensors on vehicles work? There are 4 round sensors in the rear bumper of many vehicles to provide a backup alarm. Are they optical or ultrasonic? And what measurement principles ...
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2answers
406 views

12V Battery Backup Supply for GPRS Tracker

I have little knowledge on electronics apart from following a few guides. I have made a few 7 segment displays, nothing complicated. Recently my girlfriends car was stolen and she has an insurance ...