rheostat for VGT

[72swinger360]

I've been trying to mess with the VG on my turbo. I had a small rheostat on it. It worked great for a short time. It got way to hot and burned it self out. No one around here seems to sell a bigger one that could stand up the the 12v. 2watt is whats in it. thats the biggest I can find. How are guys controlling them? Is there maybe an online store that sellls the switch?

Thanks
Jake

The turbos off an 05 PSD

[Explorer5.0]

I've been trying to mess with the VG on my turbo. I had a small rheostat on it. It worked great for a short time. It got way to hot and burned it self out. No one around here seems to sell a bigger one that could stand up the the 12v. 2watt is whats in it. thats the biggest I can find. How are guys controlling them? Is there maybe an online store that sellls the switch?

Thanks
Jake

The turbos off an 05 PSD

Most of the builds I have seen with VGT turbos involves locking the vanes in place.

[furchaser]

I wonder if a blower motor resistor would work ?

[72swinger360]

Most of the builds I have seen with VGT turbos involves locking the vanes in place.

The oil pressure keeps the vanes in the wide open position. There's a soliniod that when hooked up to a certain voltage will pull them closed.

[Colt]

 A rheostat will not work... A rheostat is cutting voltage, when you decrease voltage, you increase the amp draw of the component ( it will cause the unit to fail, I promise ya that, even if you find a rheostat that can handle it, the component will not ).. You need a PWM controller ( pulse width modulation ).. It works by giving quick pluses of voltage, so by doing that it doesnt ramp up the amp draw of the part..

 I haven't messed with the PS VGT turbo, so I dont know what the requirements of the solenoid are, otherwise I could probably find you something that would work... I've been messing with a Holset VGT turbo, which uses a stepper motor. I chose it over the PS VGT turbo due to ease of control... Thats cool you made that one work.. If you tell me more about the solenoid ( how many wires, and the resistance of the coils ), I might be able to find something that will work for ya ( it will be computer controlled though, no way around that )..

[blown99]

The actuator on that turbo is PWM (pulse width modulated).  Even if you found a reostat to adjust the voltage the solenoid will eventually burn out.  You need to make a pwm driver. 

[72swinger360]

 A rheostat will not work... A rheostat is cutting voltage, when you decrease voltage, you increase the amp draw of the component ( it will cause the unit to fail, I promise ya that, even if you find a rheostat that can handle it, the component will not ).. You need a PWM controller ( pulse width modulation ).. It works by giving quick pluses of voltage, so by doing that it doesnt ramp up the amp draw of the part..

 I haven't messed with the PS VGT turbo, so I dont know what the requirements of the solenoid are, otherwise I could probably find you something that would work... I've been messing with a Holset VGT turbo, which uses a stepper motor. I chose it over the PS VGT turbo due to ease of control... Thats cool you made that one work.. If you tell me more about the solenoid ( how many wires, and the resistance of the coils ), I might be able to find something that will work for ya ( it will be computer controlled though, no way around that )..

Thats handy to know. The solenoid has 2 wires coming out of it. How do I measure the resistance of the coils? Whats the coils?

Thanks
Jake

Heres a pic of the solenoid and rheostat I tryed using.

[72swinger360]

Would something like this work?

http://www.apogeekits.com/pulse_width_modulator.htm

[Colt]

 That might work, it will handle 6.5 amps.. I just glanced at it, I'll take a closer look here in a bit.....

 Just take a multimeter, set it to ohms and put it on the 2 wires.. Let me know what the reading is...     Basicly, that will tell me how much current the component needs..

 You can figure it yourself if you want, it's easy, just ohm's law..  You take the voltage, and divide it by the resistance... So you take 12 volts, divided by lets say 3.4 ohms.. That equals 3.529 amps.. So you'd need a driver capable of handling 3.5 amps ( plus a bit more, 5 or so just to be safe )... 

[Andy Dorsett]

The mis information in this thread is out of control.

A rheostat will not work... A rheostat is cutting voltage, when you decrease voltage, you increase the amp draw of the component ( it will cause the unit to fail, I promise ya that, even if you find a rheostat that can handle it, the component will not ).. You need a PWM controller ( pulse width modulation ).. It works by giving quick pluses of voltage, so by doing that it doesnt ramp up the amp draw of the part..

Please explain how reducing the voltage across a solenoid causes an increase in current and overheats said solenoid.

The actuator on that turbo is PWM (pulse width modulated).  Even if you found a reostat to adjust the voltage the solenoid will eventually burn out.  You need to make a pwm driver. 

What is a "PWM" solenoid and how does it differ from a normal solenoid that would work fine from a rheostat?

[Colt]

 Mis information, how the hell do you figure that? If you going to make a claim like that, why not say why you feel like that, rather than ask questions?


 You'd like me to explain it?   I'm more than happy to explain it, but I really dont see the need, why dont you try to educate me a little? If I'm wrong ( which I am not ), this shouldnt be a problem now should it?... You dont agree that any component thats rated for a certain voltage, if you under volt it, the current increases? If thats what you think, I would suggest you do a bit of research on the subject before you open your mouth..

 A PWM solenoid, solenoid may not have been the right term... It's the exact same as lets say a Ford IAC valve, put full voltage to it, it will go wide open. In order to control it's position, you control it with PWM..


 

 

[Andy Dorsett]

Would something like this work?

http://www.apogeekits.com/pulse_width_modulator.htm

Electrically this device will work assuming the solenoid does not require more than the 6.5A which I would be surprised if it were more than a couple of amps.  I would connect it to use the internal voltage reference with a simple pot.  I couldn't find a temp rating but I would assume by its contruction that regular old 0-70C stuff is used.  In an automotive environment 0C is not good.  Also the way the heat sinks and components are mounted to the board it is clearly not designed for mobile use (shock and vibration).  All of this is just to say it will not last forever but it is cheap enough maybe you don't care.

[72swinger360]

Electrically this device will work assuming the solenoid does not require more than the 6.5A which I would be surprised if it were more than a couple of amps.  I would connect it to use the internal voltage reference with a simple pot.  I couldn't find a temp rating but I would assume by its contruction that regular old 0-70C stuff is used.  In an automotive environment 0C is not good.  Also the way the heat sinks and components are mounted to the board it is clearly not designed for mobile use (shock and vibration).  All of this is just to say it will not last forever but it is cheap enough maybe you don't care.

I far from have any idea about anything electronic. I think I got the jist of that though. I'm gonna try to get my hands on a multimeter and figure out exactly what I need. Also try and find something more "mobile"


Thanks
Jake

[Andy Dorsett]

Mis information, how the hell do you figure that? If you going to make a claim like that, why not say why you feel like that, rather than ask questions?

You'd like me to explain it?   I'm more than happy to explain it, but I really dont see the need, why dont you try to educate me a little? If I'm wrong ( which I am not ), this shouldnt be a problem now should it?... You dont agree that any component thats rated for a certain voltage, if you under volt it, the current increases? If thats what you think, I would suggest you do a bit of research on the subject before you open your mouth..

There are many devices that consume more current when the input voltage is reduced and I can see how someone who knows everything they know about electronics from reading here and there would assume this is true of all devices.  It is not.  Any passive component such as a solenoid will see less current when less voltage is applied to it.  V=IR

I dont feel like I need to do any research.  I am a degreed electrical engineer with over a decade of experience with designing and testing solenoids and solenoid drivers.  I would try to educate you as you ask but I'll bet your next post will show everyone that winning this aurgument and saving some face is more important to you than learning more about solenoids.  If I'm wrong I will come back and help you understand.  Your call.

[Colt]

 I wont claim to know everything about electronics, It's nothing but a hobby to me..  We can both agree that the ideal way to control a PWM valve ( solenoid or what ever you want to call it ), is with a PWM controller, not a rheostat..   I have no problem admitting I'm wrong, I just dont like being called out when the other person has nothing to back it up with.  All ya had to do was correct me, with some info backing it, and it wouldnt have gotten under my skin. I wouldnt have called you out if you would have explained yourself. If I know something that I believe is true based on experience, and someone tells me I'm full of shit with no explaination, I expect that person to explain why. I have a feeling you were trying to make someone look like a fool, rather than help. I could be wrong, but thats how it came across.

 

 Where I screwed up what thinking of a solenoid as being like a electric motor. They are similar.  Using electro magnetism for movement.   So based from what you said, a passive component will not increase current as voltage is decreased. I would imagine that all inductive components increase current as voltage is decreased?

 Most of what I've learned is from doing it myself and seeing what the results are, and talking to people. I dont read much, I've yet to find anything written that explains things that I want to know, in a way I can understand them. I am not an engineer.

 You would be wrong about me trying to save my pride. I am here to learn. If I think I can contribute to a conversation I try to do just that, sometimes I'm wrong, and if I'm wrong I hope someone corrects me so I dont make the same mistake again. So yes, if you feel like explaining it a bit more to me, I'd appreciate it, I will never turn down a chance to learn something..

   

[Colt]

 Jake, I did a search for automotive grade PWM controllers, all I'm seeing are schematics. I cant find a assembled unit..  I'll keep looking..   If you do use the other one, you could secure the heat sinks a little better. I could be wrong, but the temp rating, I doubt that would become an issue unless you tried to operate it at or below those temps..   Could be a cheap alternative for right now, until ya find something better.

 

[72swinger360]

 Jake, I did a search for automotive grade PWM controllers, all I'm seeing are schematics. I cant find a assembled unit..  I'll keep looking..   If you do use the other one, you could secure the heat sinks a little better. I could be wrong, but the temp rating, I doubt that would become an issue unless you tried to operate it at or below those temps..   Could be a cheap alternative for right now, until ya find something better.

 

Ya I think I might order it. Thanks for all the help.


Jake

[Andy Dorsett]

Where I screwed up what thinking of a solenoid as being like a electric motor. They are similar.  Using electro magnetism for movement.   So based from what you said, a passive component will not increase current as voltage is decreased. I would imagine that all inductive components increase current as voltage is decreased?

An AC motor acts as you are describing but it is not becasue it is an inductive load.  Ignoring slip the speed of the motor is controlled by the frequency (such as 60Hz).  Since the frequency will keep the speed almost constant and it takes a certain amount of power to drive the load a given speed if the voltage goes down the current will go up (maintaining almost constant power).  A DC motor does not behave this way and will slow down and consume less current and power when the voltage is reduced.  The AC motor is the only motor I can think of right now that is this way.  Any device that is constant power or near constant power will act like this.  Voltage goes down and current goes up and visa versa.  P=VI  An MSD6 or audio amp would be like this because it has an active power supply working to maintain constant power for the device.  It is actively drawing more current to accomodate the reduced voltage.  Anything with a switching power supply at the input would behave this way.  The exception to this would be that with most devices there will be a certain voltage at which the device would shut itself off for protection.

[Andy Dorsett]

Measure the resistance of the coil and get that to us so we can take a hard look at what the options are.  Make sure you take note of the approximate temperature of the coil when the measurement is taken.

[Colt]

 I gotcha, thanks for the explaination 

[A95 5.Slow]

yeah

[72swinger360]

Well I finally got my hands on a mutimeter. The solenoid read 3.4 ohms of resistance. So if I take 14 volts divided by 3.4 ohms its 4.11 amps...I think.

Also how is the PWM controlled? Do I hook a rheostat up to it?


Thanks
Jake

[Andy Dorsett]

I am going to post my every thought as I go along.

I am going to assume that the solenoid was not hot when the resistance was measured (when it heats up its resistance will go up) and that it will not quite have 14V across it after some wiring losses (I will use 13..  This means a maximum of 4A contiuous is likely safe to design around.  4A is a lot more than I expected.

A solenoid typically will not move the device it is mechanically attached too any until the current is at least 20%.  4A X 20% = 0.8A  therefore if a rheostat is to be used it will need enough resistance to decrease the current to 0.8A.  13.8V / .8A = 17.25Ohms.  17.25Ohms - 3.5Ohms = 13.75Ohms  therefore we need at least 13.75Ohms of resistance in series with the solenoid to achieve fully off.  Power = current squared X resistance therefore 4A through a 13.75Ohm rheostat is 220W.  If you can only find a 15Ohm rheost the power would be greater and so on.  Seems so far like a driver is the solution.  More to follow.

[Andy Dorsett]

What are the operating points of this device?  Do you need infinate control between 0 and full current or is two or three descrete steps sufficient?

[72swinger360]

I'm only looking to power (move) the solenoid a small amount. The turbo's just a little bit to big. Closing the vaines half way (50% power) is way to much. Just a small amount is needed.

Seems so far like a driver is the solution.  More to follow.

By driver do you mean PWM?