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Sensors / Detectors: Automotive Circuits
Sensors / Detectors -- Main Page

Automotive: 
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Last Updated: December 31, 2017 09:54 AM
Circuits Designed by Dave Johnson, P.E. :

125khz Wireless Smart Key Detector - This circuit will turn on an indicator light whenever it detects a smart car key containing an RFID chip. . . Circuit by David A. Johnson P.E.-July, 2006

12v DC Motor with Logic Controlled Automatic Brake - There are times when you would like to control a DC motor using a simple +5v logic swing signal.  The circuit below performs this feat and also includes an automatic motor braking circuit.  When the input logic signal swings from 0v to +5v, the n-channel . . . Hobby Circuit designed by Dave Johnson P.E.-February, 2010

Capacitance Proximity Switch
Draws very low power - Ideal for battery-powered applications
6 Models Available - Call 806-368-7747




Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

10A car battery charger -  The charger is suitable for lead-acid car batteries and it is assembled in two units: a metal box with the toroidal transformer, instrument, lights, etc, and a small plastic box housing the voltage and temperature circuit.  Connection between main box and sensor is realized with a standard 3 core x 1mm, electric cable, 4m long.  its resistance is factored in the circuit calculations and it is the limiting resistor against__ 

12 Volt to 9 Volt DC Converter -  To get a more precise output voltage, replace zener diode Z1 with 10V and R1 with a 1Kilo ohm potentiometer.  A Coolrib for Q1 is optional but highly recommended.  You can replace Q1 for a more robust type to get more output amps depending on your requirements.  Simple circuit to power your 9 volt cassette recorder and other stuff __ Designed by Tony van Roon  VA3AVR

125khz Wireless Smart Key Detector -  This circuit will turn on an indicator light whenever it detects a smart car key containing an RFID chip. . . Circuit by David A. Johnson P.E.-July, 2006

12V 300W 4 channel car Amplifier -  Schematic only, no circuit description__ 

12V battery level indicator for car batteries -  This kit measures battery voltage.  The red LED (closest to the IC ) indicates a low status - 11.5Volts or less.  The yellow LED indicates 50% charge - 12.0V.  The green LED indicates 12.6V or full charge.  This kit also measures the charging status.  Turn the charging system on - or start the vehicle.  The red LED (at the extreme end from IC ) indicates overcharge - 15.5V.  The green LED indicates maximum charge voltage - 14.5V.  The yellow LED indicates normal charging voltage - 13.2V.  __ CdS Electronic

12v DC Motor with Logic Controlled Automatic Brake -  There are times when you would like to control a DC motor using a simple +5v logic swing signal.  The circuit below performs this feat and also includes an automatic motor braking circuit.  When the input logic signal swings from 0v to +5v, the n-channel . . . Hobby Circuit designed by Dave Johnson P.E.-February, 2010

12V to +/-30V DC to DC Converter -  This is a DC to DC converter for car power amplifier.12V input generates +30V and -30V output for preamp or power amplifiers.  Circuit uses SG3525 IC , MOSFETs and switching power supply__ 

13.8V Power Supply/ Charger -  A supply for testing and working on car amplifiers, up to about 500 Amps!  __ Designed by Rod Elliott  ESP

1558VIN to 33.3V 3A LED Automotive Headlight Driver with Up to 98.5% Efficiency -  Airplanes and big trucks with 24V batteries need powerful, efficient and robust headlights and spotlights.  This circuit shows a 33.3 V, 3A (nine Luminus SSR-90 LEDs) buck-boost LED driver that runs from 15V to 58V input with up to 98.5% efficiency.  The 4-switch synchronous topology drives high power LEDs with minimal switch power loss (and minimal temperature rise) __ Linear Technology/Analog Devices App Note, Mar 9th 2012

15W Mono car Amplifier using TA7227P -  Schematic only, no circuit description included__ 

160 Baud ALDL Hardware Interface -  This interface allows vehicle's ALDL data stream to be displayed in real time on a PC using simple software.  hardware is designed to be able to be constructed by average hobbyist who has a temperature controlled soldering iron and basic skills in constructing simple electronics.  it uses a minimum of (readily available) components consistent with good electronics design.  __ 

2 CMOS Based Vehicle Anti-Hijack Alarms -  Automobile Alarm Circuits:  The first circuit is designed for the situation where a hijacker forces the driver from the vehicle.  if a door is opened while the ignition is switched on - the circuit will trip.  After a few minutes delay - when the thief is at a safe distance - the alarm will sound and the engine will fail.  The second circuit is a modification of the first - offering enhanced protection in many more situations.  __ Designed by Ron J.

2 LED trouble light system -  No circuit description, schematic only__ CdS Electronic

2 More Stable Car Loop Detector -  A Better Circuit, And it is Very Stable.  Bury the coil in your driveway and it will detect any vehicle there.   __ Designed by G.L. Chemelec

2 Simple Circuit Relay Based Motorcycle Alarms -  Motorcycle Alarm Circuits:  These are two - easy to build - relay-based alarms.  You can use them to protect your motorcycle - but they have many more applications.  if you use relays with 6-volt coils - they'll protect your "Classic Bike".  Both alarms are very small.  The completed boards occupy about half a cubic-inch - 8 cc.  The standby current is zero - so they won't drain your battery.  __ Designed by Ron J.

2 Watt Switching Power Supply -  in this small switching power supply, a Schmitt trigger oscillator is used to drive a switching transistor that supplies current to a small inductor.  Energy is stored in the inductor while the transistor is on, and released into the load circuit when the transistor switches off.  The output voltage is dependent on the load resistance and is limited by a zener diode that stops the oscillator when the voltage reaches about 14 volts.  Higher or lower voltages can be obtained by adjusting the voltage divider that feeds the zener diode.  The efficiency is about 80% using a high Q inductor.   __ Designed by Bill Bowden

2-Zone Burglar Alarm -  Multi-Zone Burglar Alarm Circuits:  This two-zone alarm has automatic exit, entry and siren cut-off timers. So it has a particularly detailed circuit description.  There's an optional One-Time-Only module.  it will force the siren to switch off after the first ten minutes - and prevent the alarm from activating a second time.  __ Designed by Ron J.

30W White LED Automotive Headlamp Driver with Thermal Derating -  The LT3756, LT3756-1 and LT3756-2 are DC/DC controllers designed to operate as a constant-current source for driving high current LEDs.  They drive a low side external N-channel power MOSFET from an internal regulated 7.15V supply.  The fixed frequency, current-mode architecture results in stable operation over a wide range of __ Linear Technology/Analog Devices App Note, Jul 20th 2010

3rd Brake Light -  This circuit is NOT a pulser or flasher!  What's so special about this circuit? Well, the first third-brake light I installed I had to pull a wire from the Third Brake Light all the way underneath the carpet to the brake-pedal-switch and I thought it would be easier to pluck the signal of both brakelights via the trunk.  Bench-test your circuit first and apply power to the circuit,  __ Designed by Tony van Roon  VA3AVR

3rd Brake Light Pulser -  Several years ago these flashers were introduced in the automotive industry as part of the third brake light and contained strobe lights (and strobing continuously for the duration of pressing the break pedal) but got abandoned almost immediately sometime later because of the 'strobe' effect it has on some people.  This circuit has become obsolet since much better circuits are available these days without the 'lag' in between brakes caused by R4 and C3.  One of the circuits is listed below __ Designed by Tony van Roon  VA3AVR

50W White LED Automotive Headlamp Driver -  The LT3755, LT3755-1 and LT3755-2 are DC/DC controllers designed to operate as a constant-current source for driving high current LEDs.  They drive a low side external N-channel power MOSFET from an internal regulated 7.15V supply.  The fixed frequency, current mode architecture results in stable operation over a wide range of __ Linear Technology/Analog Devices App Note, Jul 20th 2010

5301 Wideband Fuel Mixture Display -  This is the construction guide for the 5301 wideband fuel mixture display kit.  The 5301 is the Tech Edge version (rather than the Jaycar version) of the modified Silicon Chip FMD design, and it features, compared to the original kit, double sided PCBs a new front panel design, in-built RS232 output and superbright GaAlAs 7 segment LEDs The 5301 uses the same version 1.1 software as the 5300 and, unless noted otherwise, is known elsewhere on this web site as the 5300 unit or the modified FMD display.   __ Designed by Peter Gargano 2002

555 Ignition Coil Driver -  This ignition coil driver is a HOT one!  From my recollection, it delivers a nastier spark than the legendary Ford Model T ignition coil.  The circuit uses an inverted 555 oscillator that is coupled to an ON Semiconductor BU323Z Darlington transistor (350V, 10A) that drives a conventional inductive discharge ignition coil.  in __ Designed by Jim Keith

555 -Timer Based Motorcycle Alarm -  Motorcycle Alarm Circuits:  This circuit features an intermittent siren output and automatic reset.  it can be operated manually using a key-switch or a hidden switch; but it can also be wired to set itself automatically when you turn-off the ignition.  By adding external relays you can immobilize the bike, flash the lights etc. Now With Free SiMetrix Circuit Simulation.  __ Designed by Ron J.

6V ultra-bright LED chaser using 74HC4017 -  This is a spectacular but completely useless project.  it lights Ultra-Bright LEDs in a sequence and each LED flashes brightly very briefly.  The LEDs light-up going around and around since they are mounted in a circle (on a CD) , then they pause __ Designed by Audioguru

6W Mono car Amplifier using BA521 or BA532 Amplifier Module -  Schematic only, no circuit description __ Designed by Petr Prause

94% Efficient 25W White LED Automotive Headlamp Driver -  The LT3956 is a DC/DC converter designed to operate as a constant-current source and constant-voltage regulator.  it is ideally suited for driving high current LEDs.  it features an internal low side N-channel power MOSFET rated for 84V at 3.3 A and driven from an internal regulated 7.15V supply.  The fixed frequency, current-mode __ Linear Technology/Analog Devices App Note, Jul 20th 2010

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