Ok, I want to make a light to go on whenever I'm in boost (its just good to know). Anyway, I have two sensors I can tap into, the pressure sensor for my GReddy boost gauge (1.5V at atmosphere) or the pressure sensor for my MF2 (2.4V at atmosphere). Now I have two questions:

1) How would I wire something up to turn the light on only when the voltage is where I want it (either 1.5V or 2.4V depending on which sensor I use)? I was thinking about a relay, but how would I do it? With a resistor?

2) Which of these two sensor should I tap into. I dont want to disrupt the signal or anything becuase they are both very important signals, especially the MF2 (I guess that kinda answers my question ).

Thanks.

 

Im sure there are sensors out there that can be used to measure any kind of positive pressure. Thats how early Additional injector controllers worked. AS long as the sensor switches when any positive pressure is measured you can use that by itself, and leave the other sensors to do their individual jobs. just an idea. dean

 

If you open up the MF2 and mount it somewhere where you can see it, it has an activation LED which turns on when it starts to inject, which is when you transition to boost. It also has neat LED's that run from right to left as you climb in RPM's.

 

Yeah, but I'd like have a nice LED mounted somewhere in dash cluster or on my Apillar by my boost gauge, and not have to look at a little led in the mf2.

thanks anyway

 

You can do it this way too:

1.mount a pressure switch onto the intake pipe...these are cheap and the 12V wires can easily be routed behind the firewall to light or whatever to indicate boost.

2.A little more complicated, but modify your boost gauge to so that it switches an indicator switch on whenever the needle is above zero

3. Get an electrical boost gauge and splice into the gauge signal wire.

4. Similar to #3 but do it to a boost controller.

 

No on know of anyway to do it w/ the existing sensors I have?

Oh, and Miraiz....I would be doing # 3 if I used my GReddy pressure sensor.


[Modified by 00SilverLS, 6:58 AM 1/3/2002]

 

If you do not want to disrupt either signal this is how I would do it. I would use the 1.5V greddy gauge (depending on its range).

Make a little circuit board with vector board with this on it:
12V optocoupler
12V LM regulator (optional)
12V relay or another opto
resistor for current limiting to the LED
resistor for current limiting on the opto
1.5V zener diode

Hook the diode in series with the input of the opto and the resistor you calculated to pull just above the smallest required to activate the opto. Use a 12V source on one side of the output of the opto and the relay coil on the other with the other side of the relay coil to GND. Use the 12V regulated source to drive the LED through the resistor or drop the regulator and use the 12V source, but the LED brightness will change with voltage and you will notice it. That is why I would use the 12V Lm regulator.

You can get all the parts from Digikey. I would play with it on the bench before installing it and hot glue the components to the board after you have it working properly so they don't vibrate off. The hardest part will be choosing the components that will work the best. I wasn't sure how serious you were so I didn't research the parts for exact matches.

Play with it and see if it works for you, it'll only cost you $5-$10 bucks to play with it. Use a battery to simulate the 1.5V and an old PC power supply to give you the 12V.

Randy

BTW-If the zener isn't accurate enough for you, try a schmidt trigger. They can give a more reliable hysteresis.

Disclaimer: If you don't know what the components I listed do or think a schmidt trigger is something beer-related, then I highly suggest you consult an Engineer for them to build you this.

 

My brain hurts.