OK, here's the deal. I'm going to attempt to build an auxillary supercharger bypass valve that is opened by an output voltage from my wideband O2 sensor. This is an additional safety measure in case something fails within the supercharger fuel management system.

Basically, I've got a 0-5v microcontrolled voltage source to actuate the bypass valve lever. This is a linear voltage derived directly from the A/F ratio.

I need to move a lever with a little physical resistance using a 0-5v source with a servo or whatever

It needs to be at it's fully open position at 1.75v - 2.0v

I considered using an RC aircraft type servo, but I understand you've got to convert the voltage to a pulsed signal.

Does anybody have any ideas or know where I can go for this info?

 

Sorry Jess, way outta my league. On a side note, how did the greenstuff brake pads work today. Sorry I couldn't make it, had to work all day. On my day off too, and of course, you know the drill, we don't get paid to work overtime.

I might holler at you next weekend when my Hawks come in.

I hope you get this electrical problem worked out though

 

have you look at getting a timer IC, something like a LM555 (but one that matches the voltage). it should take the voltage and pulse it. You can check National Semiconductor for an IC to match, they also have circuit diagram for their parts which should give you an idea how to go at it.

 

You'll need to research this a little more carefully for electrical system compatibility prior to even getting to a National Semi page. Servo are the easy way out, but then you'll need a control circuit just for moving the servo, which get you back to square one.

You need to thoroughly check the current needed, provided, and the beavior of the potential of the output. Much more easily handled if you have a scope. If it's something simple, like triggering a solenoid, then it's alot easier.

If you then have OrCad or some other schematic software, you can create a circuit and have a local house attach the components on a board for you. Not as trivial.

-Xray

 

If you just want to dump the valve, the problem becomes easier. Linear control - having it part way open - is tougher.

To build a circuit that actuates a solenoid when the O2 sensor reaches a specific voltage only requires an op amp/comparator, some resistors, an adjustment pot, and something (transistor or relay driving chip) to drive a 12 volt solenoid that pulls the lever. Most of those parts should be available at Radio Shack.

Now, "sorta open" would require a pulse generator, a feedback device and a servo motor, but I am not sure that an RC model plane servo would have the power or durability in a high temperature environment that you need.

Steve

 

what you need is a servo driver circuit. I use servos for many applications in my unmanned helicopter and airplane projects.

take a look at this

http://www.ferrettronics.com/docs/FT639/ft639.pdf

or this

http://www.pontech.com/products/sv200/

or this

http://www.jtecheng.com/srr2/srr2.html

all use 0-5v serial data.

As for RC servo having the power or durability.... absolutely! Servo technology has come a LONG way in the past 5 years. I have a handful of Futaba Digital servos that can lift a 5lb. brick and hold it there for an indefinate time. I've mounted them on the firewalls of cowled engine aircraft and they have been operated in some extreme heat without fail.

Just stick with a Futaba or JR Propo servo and you'll have no troubles.

 

Thanks for the info, but it looks like the easiest way is going to be a dump valve activated by a vacuum switch. I appreciate the input though and maybe someday I'll have something a little more high tech. I just want to be able to dump boost for now in case something catastrophic happens to my FMU or one of my injectors goes when I'm on boost. Never can be too safe.

 

I'm an EE but deal w/ utilities instead. I wish I could help, but your inquiry seems to deal more w/ controls since it involves feedbacks and loops.