Neither EFILive or the factory sensor can read amps. I don't know how to convert between amps and volts yet. I would like to turn 4 milliamps to 0.5 volts, and 20 milliamps to 4.5 volts. I know it can be done, I just don't know how.
Sensors, Ohm's law, and gauges.
- Thread starter McRat
- Start date
Neither EFILive or the factory sensor can read amps. I don't know how to convert between amps and volts yet. I would like to turn 4 milliamps to 0.5 volts, and 20 milliamps to 4.5 volts. I know it can be done, I just don't know how.
Pat if u have 4 milliamps and u want .5 volts that will give u 2 watts.
If u got 20 milliamps and want 4.5 u will have 4.44444 omps of resitenace. I beilver my math is correct.
Am i understanding u correctly or am i totally off base?
Basic Voltage Divider circuit -
Let's say your truck makes 14 volts when it's running. But you want 5.0V so you can supply a sensor with it's power.
Look at the first pic. For resistor A, you will use 360 ohms, and for resistor B you use 200. Now the "lower voltage" side will give you 5 volts.
But what we really need this for is turning a variable resistor sensor (milliamp) sensor into a 0-5V sensor. By selecting the right Resistor A, we can output variable voltage to EFILive or the factory EGR signal wire. Normally it will be about 200-500 ohms.
Let's say your truck makes 14 volts when it's running. But you want 5.0V so you can supply a sensor with it's power.
Look at the first pic. For resistor A, you will use 360 ohms, and for resistor B you use 200. Now the "lower voltage" side will give you 5 volts.
But what we really need this for is turning a variable resistor sensor (milliamp) sensor into a 0-5V sensor. By selecting the right Resistor A, we can output variable voltage to EFILive or the factory EGR signal wire. Normally it will be about 200-500 ohms.
Attachments
The "milliamps" change depending on what the sensor is seeing. Yes, amp*volts = watts, and amps = volts / resistance.
Watts are a measure of power, but we don't want power to run anything, we just want to "see" what is going on, the less power the better.
Looks like NorCal Nick just removed his PDF, night see if he'll part with them.
http://www.dieselplace.com/forum/showthread.php?t=230977
SPA sending unit - .99v at atmospheric
1.25 at 15PSI
1.50 a 30PSI
1.75 at 44PSI
2.04 at 60PSI
2.50 at 90psi
2.66 at 100PSI
3.00 at 120PSI
Seems it goes to 240? at 5.0V. Too much range for what we need. Could do with an amplifier, 2:1.
1.25 at 15PSI
1.50 a 30PSI
1.75 at 44PSI
2.04 at 60PSI
2.50 at 90psi
2.66 at 100PSI
3.00 at 120PSI
Seems it goes to 240? at 5.0V. Too much range for what we need. Could do with an amplifier, 2:1.
Could not get turbocharger vane position sensor to report on either EFILive or Tech2. Without a "voltage" PID, this one perhaps can't work since it seems it relies on the charger being functional to report.
Pat
These are basic, but only if voltage is constant. To make these work with our varying voltage, a regulator needs to be incorporated.
Luckily we have a tightly regulated 5v available:
The USB port on the notebook, or any sensor on the engine. Both are 5-5.1 volts.
Using these sources, good ones for sure, care has to be taken to keep from using too much current. Short one of these and boom, or smoke for sure. Do you remember that drive pressure thing along time ago? If so, I'll send it over to ya if your still interested. May help for a voltage source.
You can use any 12v source in the truck, and just wire in an L7805 voltage regulator. About 25 cents from radio shack.
