Author Topic: How to improve Solenoids open/close response time ?  (Read 17111 times)

0 Members and 1 Guest are viewing this topic.

Offline AlbatroonTopic starter

  • Contributor
  • Posts: 30
  • Country: eg
Re: How to improve Solenoids open/close response time ?
« Reply #25 on: March 16, 2019, 10:13:05 pm »
If you have many valves in a complex system you wight want to consider having two rails (+V, 0, -V) so you can first connect between +V and -V and then switch to half voltage.
Thank you for your suggestion.

The bootstrapping idea is a good one. Note that each transistor should have its own base resistor, which has been omitted from the schematic.

To improve the turn off speed, a zener diode can be added in reverse parallel with Q2.

Yes, the main drawback with that circuit is it takes awhile for C1 to charge, via R1which will limit the repetition rate. R1 can be replaced with a current source or better still, another transistor. THe Hfe of Q3 will determine the charging current, so there's a bit of "Hfe suicide" here, but it should be fine.
Is the inductor Necessary ? What it do in this circuit ?
 

Online ebastler

  • Super Contributor
  • ***
  • Posts: 7375
  • Country: de
Re: How to improve Solenoids open/close response time ?
« Reply #26 on: March 16, 2019, 10:19:29 pm »
@Albatroon, I have two questions:
  • You have not really told us about your application. What switching speeds are you targeting? Beyond spped, how many switching cycles (per hour, per day, over the lifetime of the product) do you need? Are relays the right solution, or should you look at solid-state switches?
  • Who the heck is Bob? ;) You start referring to "Bob's design" mid-thread, but I could not find a reference for that?
 

Offline AlbatroonTopic starter

  • Contributor
  • Posts: 30
  • Country: eg
Re: How to improve Solenoids open/close response time ?
« Reply #27 on: March 16, 2019, 10:26:33 pm »
@Albatroon, I have two questions:
  • You have not really told us about your application. What switching speeds are you targeting? Beyond spped, how many switching cycles (per hour, per day, over the lifetime of the product) do you need? Are relays the right solution, or should you look at solid-state switches?
  • Who the heck is Bob? ;) You start referring to "Bob's design" mid-thread, but I could not find a reference for that?

I posted my project on Replay #16.. Here's my replay:
By the way, I am driving about 200 solenoids, many times per second.
I started this project back in 2012, I Built this https://youtu.be/YtlYc2bzUEs?t=10.
Now I am trying to build a new one with batter valves, better performance & a Bigger size !
And about Bob's design.. It took awhile for me too to find what "rstofer" mean on replay #8.

The fastest it will run is with no diodes but that isn't possible because there is a body diode in the MOSFET.

There is a possibility of some kind of capacitive discharge circuit that forcibly opens the solenoid by driving a reverse current through the inductor.  No, I don't now how to do it and I didn't find much on Google.

Here's a circuit that is interesting but it only works on pull-in:

https://www.electronicdesign.com/analog/what-s-all-solenoid-driver-stuff-anyhow

Basically, you have a lot of stored energy in the inductance and all the time it is discharging, there is current flow through the solenoid.

Here's an idea:  Use Bob's circuit above to pull the solenoid in and then reduce the current to some lower value for hold-in. Now when it comes time to drop out, you have less current flow so less stored energy and the release is faster.  Couple that with the Zener approach and maybe you'll have something.
Bob's design is here https://www.electronicdesign.com/analog/what-s-all-solenoid-driver-stuff-anyhow

Thank you
 
The following users thanked this post: ebastler

Online Zero999

  • Super Contributor
  • ***
  • Posts: 20357
  • Country: gb
  • 0999
Re: How to improve Solenoids open/close response time ?
« Reply #28 on: March 16, 2019, 11:01:22 pm »
If you have many valves in a complex system you wight want to consider having two rails (+V, 0, -V) so you can first connect between +V and -V and then switch to half voltage.
Thank you for your suggestion.

The bootstrapping idea is a good one. Note that each transistor should have its own base resistor, which has been omitted from the schematic.

To improve the turn off speed, a zener diode can be added in reverse parallel with Q2.

Yes, the main drawback with that circuit is it takes awhile for C1 to charge, via R1which will limit the repetition rate. R1 can be replaced with a current source or better still, another transistor. THe Hfe of Q3 will determine the charging current, so there's a bit of "Hfe suicide" here, but it should be fine.
Is the inductor Necessary ? What it do in this circuit ?
The inductor represents the solenoid of course.
 
The following users thanked this post: Albatroon

Online ebastler

  • Super Contributor
  • ***
  • Posts: 7375
  • Country: de
Re: How to improve Solenoids open/close response time ?
« Reply #29 on: March 16, 2019, 11:10:31 pm »
You have not really told us about your application. What switching speeds are you targeting? Beyond spped, how many switching cycles (per hour, per day, over the lifetime of the product) do you need? Are relays the right solution, or should you look at solid-state switches? [/li][/list]

I posted my project on Replay #16.. Here's my replay:
By the way, I am driving about 200 solenoids, many times per second.
I started this project back in 2012, I Built this https://youtu.be/YtlYc2bzUEs?t=10.
Now I am trying to build a new one with batter valves, better performance & a Bigger size !

Oh, thank you -- and my apologies for overlooking that information in your earlier post.
That is a pretty cool project indeed!

Obviously, solid-state water valves are hard to come by, so solenoids it is...  ;)
How long do they typically last in this application?
 

Offline AlbatroonTopic starter

  • Contributor
  • Posts: 30
  • Country: eg
Re: How to improve Solenoids open/close response time ?
« Reply #30 on: March 16, 2019, 11:16:24 pm »
Obviously, solid-state water valves are hard to come by, so solenoids it is...  ;)
How long do they typically last in this application?

Thank you, solenoids are working great since 2012.. The only problem i faced with my PCB designs, I had 24 pcs of 595's exploded on me :D
It was a wrong design and I overloaded the ULN2803A chips, one of them burnt and 24v return on Negative, all board destroyed :D
Other than, Valves are working good till now..
 
The following users thanked this post: ebastler

Offline AlbatroonTopic starter

  • Contributor
  • Posts: 30
  • Country: eg
Re: How to improve Solenoids open/close response time ?
« Reply #31 on: March 16, 2019, 11:36:30 pm »
The inductor represents the solenoid of course.

Will this circuit work If i changed the Transistors with Darlington transistors ?
My solenoid are working on 24v, ~0.4A I need a bigger transistors to drive them.
And if it possible, Should I change the 3 or only q2 ?

And What software you used for this simulation ?

Thank you
« Last Edit: March 16, 2019, 11:56:46 pm by Albatroon »
 

Online Zero999

  • Super Contributor
  • ***
  • Posts: 20357
  • Country: gb
  • 0999
Re: How to improve Solenoids open/close response time ?
« Reply #32 on: March 17, 2019, 12:04:16 am »
The inductor represents the solenoid of course.

Will this circuit work If i changed the Transistors with Darlington transistors ?
My solenoid are working on 24v, ~0.4A I need a bigger transistors to drive them.

And What software you used for this simulation ?

Thank you
Why do you think you need bigger transistors?

The BC337 is rated to 800mA, double the current rating of your solenoids,
https://www.onsemi.com/pub/Collateral/BC337-D.PDF

Darlington transistors will work in the circuit, but they have a much higher saturation voltage. Even the circuit I posted with no modifications will drop less voltage than the same one with Darlington pairs.

I used LTSpice to simulate the circuit. Some say it has a steep learning curve, but I found it fairly straightforward.
 
The following users thanked this post: Albatroon

Offline AlbatroonTopic starter

  • Contributor
  • Posts: 30
  • Country: eg
Re: How to improve Solenoids open/close response time ?
« Reply #33 on: March 17, 2019, 01:01:54 am »
Why do you think you need bigger transistors?

The BC337 is rated to 800mA, double the current rating of your solenoids,
https://www.onsemi.com/pub/Collateral/BC337-D.PDF

Darlington transistors will work in the circuit, but they have a much higher saturation voltage. Even the circuit I posted with no modifications will drop less voltage than the same one with Darlington pairs.

I used LTSpice to simulate the circuit. Some say it has a steep learning curve, but I found it fairly straightforward.

I'll try this software, Looks simple!
What Zener should I use ? Any one would work ? Should I get a big one, Like 1w zener ? or anything will work ?

Thank u
 

Offline Teledog

  • Regular Contributor
  • *
  • Posts: 217
  • Country: ca
Re: How to improve Solenoids open/close response time ?
« Reply #34 on: March 17, 2019, 04:17:38 am »
Perhaps I've missed something..but  how about sealed SSRs?
 

Offline SeanB

  • Super Contributor
  • ***
  • Posts: 16385
  • Country: za
Re: How to improve Solenoids open/close response time ?
« Reply #35 on: March 17, 2019, 07:06:24 am »
Instead of zener diodes use transorb diodes, 5W ones will work well there, and using bidirectional ones will be fine, just put them directly across the terminals of the solenoids, so the spike is attenuated the most before it reaches the control board. Voltage is selected so the peak voltage, at the solenoid operate current through the diode, is less than the maximum recommended voltage of your power switching device less the maximum supply voltage from your power supply. That way the magnetic field collapses the fastest, while still allowing the power switch to survive.
 
The following users thanked this post: Albatroon

Offline soldar

  • Super Contributor
  • ***
  • Posts: 3595
  • Country: es
Re: How to improve Solenoids open/close response time ?
« Reply #36 on: March 17, 2019, 08:16:48 am »
Albatroon, this is a cool and very interesting project.  Some thoughts:

The speed with which the solenoid can move is only one factor in how fast the water flow will start or stop. At these fast speeds every little thing counts.

What pressure are you using for the water? What solenoid valves are you using? Are they designed for fast response? Because there is only so much you can do with the electronics and you need to look also at the electromechanical and fluids aspects. I see there are "fast" valves that have a response time of about 20 mS and you can get super-fast valves that will respond in 2 mS.

You should try to avoid long tubes that add inertia to the fluid. The best design would be to have the valve right next to the jet orifice and connected, not to a long pipe but to a common manifold water header for all the valves.

The switching transistor should be oversized in current and voltage specs. While the solenoid armature is moving the inductance decreases a lot and the current increases a lot. And the switching voltage transients should be limited with zener diodes or other means.

Also, heat dissipation and operating temperature should be taken into account.

 
« Last Edit: March 17, 2019, 09:03:09 am by soldar »
All my posts are made with 100% recycled electrons and bare traces of grey matter.
 

Online ebastler

  • Super Contributor
  • ***
  • Posts: 7375
  • Country: de
Re: How to improve Solenoids open/close response time ?
« Reply #37 on: March 17, 2019, 08:42:42 am »
Perhaps I've missed something..but  how about sealed SSRs?

Yes, I believe you did miss something. (I'll reply since I had missed it too...) This project is not about driving relays, but solenoid-operated valves to control liquid flow. See replies 16 and 27 above.
 
The following users thanked this post: Albatroon

Offline AlbatroonTopic starter

  • Contributor
  • Posts: 30
  • Country: eg
Re: How to improve Solenoids open/close response time ?
« Reply #38 on: March 17, 2019, 09:39:12 am »
Albatroon, this is a cool and very interesting project.  Some thoughts:

The speed with which the solenoid can move is only one factor in how fast the water flow will start or stop. At these fast speeds every little thing counts.

What pressure are you using for the water? What solenoid valves are you using? Are they designed for fast response? Because there is only so much you can do with the electronics and you need to look also at the electromechanical and fluids aspects. I see there are "fast" valves that have a response time of about 20 mS and you can get super-fast valves that will respond in 2 mS.

You should try to avoid long tubes that add inertia to the fluid. The best design would be to have the valve right next to the jet orifice and connected, not to a long pipe but to a common manifold water header for all the valves.

The switching transistor should be oversized in current and voltage specs. While the solenoid armature is moving the inductance decreases a lot and the current increases a lot. And the switching voltage transients should be limited with zener diodes or other means.

Also, heat dissipation and operating temperature should be taken into account.

Thank you for your reply, I am only using the gravity feed pressure, This allow the dropped pixels to be at lowest speed.
The solenoid valves I used is the best valves I can pay for, In this version I am using 192 solenoid valves.
Those ultra fast solenoid valves are very expensive. I Used the best Chinese solenoid valves I can find and afford.
I am fine tuning this new build step by step. stating with the control boards, Than I'll play with pressure, tubes, Orifices & maybe some RGBs :D

Thank you for your help
 

Offline soldar

  • Super Contributor
  • ***
  • Posts: 3595
  • Country: es
Re: How to improve Solenoids open/close response time ?
« Reply #39 on: March 17, 2019, 11:06:36 am »
Thank you for your reply, I am only using the gravity feed pressure, This allow the dropped pixels to be at lowest speed.
The solenoid valves I used is the best valves I can pay for, In this version I am using 192 solenoid valves.
Those ultra fast solenoid valves are very expensive. I Used the best Chinese solenoid valves I can find and afford.
I am fine tuning this new build step by step. stating with the control boards, Than I'll play with pressure, tubes, Orifices & maybe some RGBs :D
OK, this changes how I see the problem very radically. I think you probably do not need high speed valves at all and you probably do not need to make your valves open particularly fast. You probably do not need any bootstrap circuit to make the solenoid move faster. We are talking fairly low speeds here.

Here is something I would do. Measure the time between voltage applied to solenoid and water starts flowing. Measure time between power shut off from solenoid and water stops flowing. If those two numbers are quite similar then there will just be a delay between electrical signals and water flow but that is irrelevant. If they are substantially different then you can account for that in software.

At this point I do not think making the solenoid valves act faster is going to have any appreciable effect and I would try to go with the simplest solenoid switch with a single transistor.

All my posts are made with 100% recycled electrons and bare traces of grey matter.
 

Offline AlbatroonTopic starter

  • Contributor
  • Posts: 30
  • Country: eg
Re: How to improve Solenoids open/close response time ?
« Reply #40 on: March 17, 2019, 11:13:49 am »
]OK, this changes how I see the problem very radically. I think you probably do not need high speed valves at all and you probably do not need to make your valves open particularly fast. You probably do not need any bootstrap circuit to make the solenoid move faster. We are talking fairly low speeds here.

Here is something I would do. Measure the time between voltage applied to solenoid and water starts flowing. Measure time between power shut off from solenoid and water stops flowing. If those two numbers are quite similar then there will just be a delay between electrical signals and water flow but that is irrelevant. If they are substantially different then you can account for that in software.

At this point I do not think making the solenoid valves act faster is going to have any appreciable effect and I would try to go with the simplest solenoid switch with a single transistor.
.

Noted, Thank you, I'll do more tests before designing new PCBs

Thank you for your support  :-+
 

Online Zero999

  • Super Contributor
  • ***
  • Posts: 20357
  • Country: gb
  • 0999
Re: How to improve Solenoids open/close response time ?
« Reply #41 on: March 17, 2019, 11:36:37 am »
Albatroon, this is a cool and very interesting project.  Some thoughts:

The speed with which the solenoid can move is only one factor in how fast the water flow will start or stop. At these fast speeds every little thing counts.

What pressure are you using for the water? What solenoid valves are you using? Are they designed for fast response? Because there is only so much you can do with the electronics and you need to look also at the electromechanical and fluids aspects. I see there are "fast" valves that have a response time of about 20 mS and you can get super-fast valves that will respond in 2 mS.

You should try to avoid long tubes that add inertia to the fluid. The best design would be to have the valve right next to the jet orifice and connected, not to a long pipe but to a common manifold water header for all the valves.

The switching transistor should be oversized in current and voltage specs. While the solenoid armature is moving the inductance decreases a lot and the current increases a lot. And the switching voltage transients should be limited with zener diodes or other means.

Also, heat dissipation and operating temperature should be taken into account.
Increasing the voltage and therefore the current to the solenoid might make it switch faster, because it will apply more force to the valve.

Putting the solenoids, as near to the jets as possible is good advice. It will also help if the tube after the solenoids is as rigid as possible.

I'll try this software, Looks simple!
What Zener should I use ? Any one would work ? Should I get a big one, Like 1w zener ? or anything will work ?
The power rating of the zener depends on the operating frequency and the inductance of the solenoid.

Thinking about this circuit in more detail, how are you driving it? I know you mentioned the 595: is that the old TTL type i.e. the 74(LS)595 or 74HC(T)595? If you're using the old TTL type, then it won't have enough drive to Q1 and Q2. I'd recommend the 74AC(T)595, which should be able to drive the circuit directly.

Other possibilities are: Darlington pairs for Q1 and Q2, additional driver transistors, or MOSFETs which would require an additional driver IC.

One thing I didn't consider before is the power dissipation in Q3, which could be too high if it's switched frequently enough. Dissipating some of the power in a series resistor would help.
 

Offline soldar

  • Super Contributor
  • ***
  • Posts: 3595
  • Country: es
Re: How to improve Solenoids open/close response time ?
« Reply #42 on: March 17, 2019, 12:03:26 pm »
Increasing the voltage and therefore the current to the solenoid might make it switch faster, because it will apply more force to the valve.

Yes, we all agree on that but at this point I am not convinced it would make much or any difference. I think other factors, like low water pressure, have much more of an effect than the speed of the solenoid. And what is the need, anyway?

I am reminded of a story about a French general who was visiting some military base and said he wanted a certain road lined on both sides with a certain kind of tree (I forget the exact type). The gardener in charge was called and the general told him "tomorrow morning I want you to plant rows of (type?) trees on both sides of the road because they would look good and provide shade." The gardener remarked to the general that those trees grew very, very slowly and took over one hundred years to reach maturity to which the general said "well, then, we better not wait and you should start planting them this very afternoon".

At this point I am not convinced speeding up the actuation of the valve does anything other than complicate the project and introduce causes for problems down the road.

Albatroon what makes you think of the need for this? What is the problem you are trying to solve?
« Last Edit: March 17, 2019, 12:10:49 pm by soldar »
All my posts are made with 100% recycled electrons and bare traces of grey matter.
 

Offline AlbatroonTopic starter

  • Contributor
  • Posts: 30
  • Country: eg
Re: How to improve Solenoids open/close response time ?
« Reply #43 on: March 17, 2019, 12:14:17 pm »
Albatroon what makes you think of the need for this? What is the problem you are trying to solve?
There's no problems at all, I can drive the valves with simple Transistor. I did it before and worked good enough.
All what I am hopping is MAKE IT BETTER. I
That's why I doing my research, Asking here.. Testing different circuits to Achieve the best result !

Thinking about this circuit in more detail, how are you driving it? I know you mentioned the 595: is that the old TTL type i.e. the 74(LS)595 or 74HC(T)595? If you're using the old TTL type, then it won't have enough drive to Q1 and Q2. I'd recommend the 74AC(T)595, which should be able to drive the circuit directly.
I am using 74HC595, And It's the only option for me here in Egypt.
I'll breadboard this circuit today and check with the scope, Wish me luck !

Thank you All !
 

Offline MrAl

  • Super Contributor
  • ***
  • Posts: 1666
Re: How to improve Solenoids open/close response time ?
« Reply #44 on: March 17, 2019, 01:17:51 pm »
Hi,

Just to note, the energy stored in the coil is proportional to the Volt Seconds which is simply volts times the time in seconds.  That means to dissipate a given energy W first the stored energy can be looked at as:
W=v*s*K

with K a constant, and to dissipate that energy we have to dissipate W units, so we have the same:
W=v*s*K

Now if we quantify the energy going in:
W1=v1*t1*K

and going out:
W2=v2*t2*K

and so with unsigned voltages we must have close to:
W2=W1

to dissipate nearly all the energy.

This simply means:
v2*t2*K=v1*t1*K

reducing, we get:
v2*t2=v1*t1

and if we solve for the dissipation time we get:
t2=t1*v1/v2

and here it is plain to see that as we increase v2 the time t2 reduces and that's the goal.
t1 is automatically limited because of the fixed voltage v1, but obviously if v1 is lowered t2 reduces that way too.
So the rule is minimum v1, maximum v2.  The practical limit on v2 is closely related to the drain source voltage rating of the transistor so the choice of transistor is also a key factor.
 
The following users thanked this post: Albatroon

Offline soldar

  • Super Contributor
  • ***
  • Posts: 3595
  • Country: es
Re: How to improve Solenoids open/close response time ?
« Reply #45 on: March 17, 2019, 01:21:05 pm »
There's no problems at all, I can drive the valves with simple Transistor. I did it before and worked good enough.
All what I am hopping is MAKE IT BETTER. I
That's why I doing my research, Asking here.. Testing different circuits to Achieve the best result !
Make it better? That is quite vague. Better in what way? Because complicating the drive circuit for no discernable effect is not going to make it "better" but will make it more complex, expensive and prone to failures.

If you want to improve something, anything,  the first thing to establish is what exactly are we trying to achieve. "Better" is meaningless as too broad.

You have a working design but you want to make it "better".  If a viewer saw the initial product and then the improved product in what way would he say it is better?

Because, you might have heard "if it ain't broke don't fix it". I do not know what we are trying to fix here.

Suppose we add some electronics and the solenoid opens one millisecond faster. What effect will it have? What leads you to believe the effect will be noticeable?
 
All my posts are made with 100% recycled electrons and bare traces of grey matter.
 

Offline AlbatroonTopic starter

  • Contributor
  • Posts: 30
  • Country: eg
Re: How to improve Solenoids open/close response time ?
« Reply #46 on: March 17, 2019, 03:57:53 pm »
Make it better? That is quite vague. Better in what way? Because complicating the drive circuit for no discernable effect is not going to make it "better" but will make it more complex, expensive and prone to failures.

If you want to improve something, anything,  the first thing to establish is what exactly are we trying to achieve. "Better" is meaningless as too broad.

You have a working design but you want to make it "better".  If a viewer saw the initial product and then the improved product in what way would he say it is better?

Because, you might have heard "if it ain't broke don't fix it". I do not know what we are trying to fix here.

Suppose we add some electronics and the solenoid opens one millisecond faster. What effect will it have? What leads you to believe the effect will be noticeable?

I mean by better here a better resolution.
If the valves Open/Closed faster than they are now, It supposed to have a better image quality.
Maybe If i forced those valves with a better drivers I achieve my goal..
And I'll compare the classic transistor driver with this new circuit to see if any Improvement.

I saw some videos for companies out there built this fountain, Some of them looks amazing.
I know that my valves are not the best.. I am just trying to get the most performance out of them.

 

Offline AlbatroonTopic starter

  • Contributor
  • Posts: 30
  • Country: eg
Re: How to improve Solenoids open/close response time ?
« Reply #47 on: March 17, 2019, 04:01:19 pm »
Hi,

Just to note, the energy stored in the coil is proportional to the Volt Seconds which is simply volts times the time in seconds.  That means to dissipate a given energy W first the stored energy can be looked at as:
W=v*s*K

with K a constant, and to dissipate that energy we have to dissipate W units, so we have the same:
W=v*s*K

Now if we quantify the energy going in:
W1=v1*t1*K

and going out:
W2=v2*t2*K

and so with unsigned voltages we must have close to:
W2=W1

to dissipate nearly all the energy.

This simply means:
v2*t2*K=v1*t1*K

reducing, we get:
v2*t2=v1*t1

and if we solve for the dissipation time we get:
t2=t1*v1/v2

and here it is plain to see that as we increase v2 the time t2 reduces and that's the goal.
t1 is automatically limited because of the fixed voltage v1, but obviously if v1 is lowered t2 reduces that way too.
So the rule is minimum v1, maximum v2.  The practical limit on v2 is closely related to the drain source voltage rating of the transistor so the choice of transistor is also a key factor.

Too much for a Hobbyist to understand ;D
 

Offline Richard Crowley

  • Super Contributor
  • ***
  • Posts: 4321
  • Country: us
  • KJ7YLK
Re: How to improve Solenoids open/close response time ?
« Reply #48 on: March 17, 2019, 05:04:30 pm »
Isn't it common practice for higher performance to drive stepper motors with a higher voltage than rated, but with a series resistance to limit the steady-state current.  The reasoning being that provides a higher immediate current (while the coil is "charging") for fast action, while limiting "resting" current to safe levels for the motor.

There are several different designs of solenoid-operated valves. I would think that the exact nature of the valve design (and the static pressure of the source) might be even more critical parts of this exercise than the speed at which you can drive it open and closed.
« Last Edit: March 17, 2019, 05:21:51 pm by Richard Crowley »
 

Online Zero999

  • Super Contributor
  • ***
  • Posts: 20357
  • Country: gb
  • 0999
Re: How to improve Solenoids open/close response time ?
« Reply #49 on: March 17, 2019, 05:25:38 pm »
I have been involved in a similar project before, which did a similar thing but with high pressure air. Instead of bootstrapping or series resistors, a separate higher voltage power supply was used. A negative supply voltage was also used to speed up the turn off time. Unfortunately I wasn't involved in the design, so can't comment on whether any of it was necessary. I think the higher positive voltage might have helped with the speed, but I thing the negative voltage was just an over-complication.

It's possible that the solenoid might not be the main bottleneck in the speed, but more investigation is necessary to determine this.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf