Arduino in automotive

[hwlite]

I'm building a vehicle powered veggy oil run controller. Doesn't start using veggy oil (pull veggy solenoid) until warmed up and, when running on veggy, doesn't shutoff engine with ignition going off (you take keys out and lock car, it switches back to diesel and runs on (to purge fuel lines and injector pump - so it do will start cold). ((Up and running on jumper battery now - ready to connect to vehicle power.)) First problem is voltage surges. Need simple choke, zener diode, and cap. circuit (?) to go along with arduino regulator. Don't know cap and chokes but figuring charge at 14v and arduino OK at 8.2v (regulation fails at 6v) - the zener and resistor for a 100mA (50mA for it and 50 for two relays) to the "vin" supply, the circuit should be:

___-----(R1)------------------>
___+14v_______I_______+8.2v
______________I
Battery_______(Z1)______Arduino
______________I
______________I
___---------------------------->
Gnd

with:
Z1 zener diode at 8.2v and 700 mW (use 2 watts for surges)
R1 resistor at 70 ohms and 2 watts

and to protect arduino:
2x capacitors?
2x chokes?

Correct?

 

[hwlite]

Sorry about the picture - the underlines fill blank spaces.

 

[hwlite]

Seems like capacitors are not needed, arduino will regulate?

 

[kchriste]

If the arduino already has a 5V regulator, there is no need for a 8.2V zener. A choke, cap, and maybe a transorb or TVS diode as well should be all you need on the power supply line.

 

[hwlite]

Arduino Automotive

If the arduino already has a 5V regulator, there is no need for a 8.2V zener. A choke, cap, and maybe a transorb or TVS diode as well should be all you need on the power supply line.

What _size_ of cap and choke? I'll lookup a transorb and TVS diodes and get back. Live test is next. Will get back to thread again after test. Thanks.

Step
___1: design basics.
___2: up and tested.
On 3: error detect & surge protection,
___4: board layout
___5: board mfg...

 

[kchriste]

Boncuk posted a good example here.
I would probably use a TVS with a slightly higher breakdown voltage just in case your vehicle has it's alternator voltage regulator set a little high.