karenhornby
New Member
Hi all and thanks in advance to anyone that can help me.
What I want to do is make an auto switchover circuit that will switch between 2 different fuel tanks in the car, one containing vegetable oil, and the other diesel.
It will have 2 +12VDC inputs, one from the car battery. and the second from the ignition switch, so the circuit is always powered but the main switchover electronics only actually turns on when the ignition is on
The car will start on Diesel, and when the temperature OUT of the injection pump reaches 45ºC AND the temp of the water coolant in the car reaches 70ºC then a circuit will operate that switches 2 relays (or solid state devices that will handle the current drawn by 2 X "Tecalemit standard 3 port solenoid valve" AND light a BLUE LED.
I've no idea at the moment of the current drawn by these vales, but as its a small solenoid I would guess its around 1A?
Anyway back to the project,
IF the temperature out of the injection pump drops BELOW 40ºC then the circuit will switch off and both relays will disengage, effectively switching the car back to diesel. (this will also disengage the Blue LED) BUT will switch OFF the Blue LED and light a FLASHING RED LED but will NOT activate the buzzer
Also needed is a timer circuit that when you press a single non latching pushbutton switch (s1) will switch relay 1 off, and keep relay 2 on for a period of 60 seconds and at the same time light a (solid non flashing) RED LED(for the 60 seconds) this is to "flush" "purge" the vegetable oil out of the injection pump so it wont damage it with cold oil.
IF the ignition is turned off WITHOUT the pushbutton (s1) then the relays will BOTH disengage (ie the circuit effectively turns off) BUT a buzzer/mini siren will sound for a period of 60 seconds to remind me to switch the ignition on to clear the vegetable oil out of the injection pump and the buzzer/mini siren will ONLY turn off once S1 is pressed.
I was originally going to try and design/build this using a pic chip or similar and also have an input from the veg oil fuel tank, that would switch the circuit back to diesel when the tank got extremely low on oil, and would have also have had a digital display showing the actual temperatures of the injection pump output and the cars cooling system and display which fuel the vehicle was running on.
Oh one last thing. it must have a master on/off switch in case I (or the other half) was stupid enough to forget to fill the veg oil tank and we could switch the whole circuit off.
By the way I'm located in England if that makes any difference, and yes I know I could just go and buy a controller already made up, but they cost between $500- $1000 just for the actual kit, its not as much fun as building something yourself, none of the kits monitor both temperatures and dont switchover unless both temperatures are right and the main reason.. I can't afford to buy a ready built kit.!
I need this to be pretty inexpensive and not many parts, I was going to try and utilise the circuit I've attached (borrowed from another thread) but to be honest I'd rather do it right first time than try and end up "botching it"
What I want to do is make an auto switchover circuit that will switch between 2 different fuel tanks in the car, one containing vegetable oil, and the other diesel.
It will have 2 +12VDC inputs, one from the car battery. and the second from the ignition switch, so the circuit is always powered but the main switchover electronics only actually turns on when the ignition is on
The car will start on Diesel, and when the temperature OUT of the injection pump reaches 45ºC AND the temp of the water coolant in the car reaches 70ºC then a circuit will operate that switches 2 relays (or solid state devices that will handle the current drawn by 2 X "Tecalemit standard 3 port solenoid valve" AND light a BLUE LED.
I've no idea at the moment of the current drawn by these vales, but as its a small solenoid I would guess its around 1A?
Anyway back to the project,
IF the temperature out of the injection pump drops BELOW 40ºC then the circuit will switch off and both relays will disengage, effectively switching the car back to diesel. (this will also disengage the Blue LED) BUT will switch OFF the Blue LED and light a FLASHING RED LED but will NOT activate the buzzer
Also needed is a timer circuit that when you press a single non latching pushbutton switch (s1) will switch relay 1 off, and keep relay 2 on for a period of 60 seconds and at the same time light a (solid non flashing) RED LED(for the 60 seconds) this is to "flush" "purge" the vegetable oil out of the injection pump so it wont damage it with cold oil.
IF the ignition is turned off WITHOUT the pushbutton (s1) then the relays will BOTH disengage (ie the circuit effectively turns off) BUT a buzzer/mini siren will sound for a period of 60 seconds to remind me to switch the ignition on to clear the vegetable oil out of the injection pump and the buzzer/mini siren will ONLY turn off once S1 is pressed.
I was originally going to try and design/build this using a pic chip or similar and also have an input from the veg oil fuel tank, that would switch the circuit back to diesel when the tank got extremely low on oil, and would have also have had a digital display showing the actual temperatures of the injection pump output and the cars cooling system and display which fuel the vehicle was running on.
Oh one last thing. it must have a master on/off switch in case I (or the other half) was stupid enough to forget to fill the veg oil tank and we could switch the whole circuit off.
By the way I'm located in England if that makes any difference, and yes I know I could just go and buy a controller already made up, but they cost between $500- $1000 just for the actual kit, its not as much fun as building something yourself, none of the kits monitor both temperatures and dont switchover unless both temperatures are right and the main reason.. I can't afford to buy a ready built kit.!
I need this to be pretty inexpensive and not many parts, I was going to try and utilise the circuit I've attached (borrowed from another thread) but to be honest I'd rather do it right first time than try and end up "botching it"
