[gmcjetpilot]

Cool new electonic filter device

http://www.miracleantenna.com/Smoothie.htm

This baby does it all. One thing that I found interesting according to the manufacture is sometime electronics like engine monitors can make noise and 'pollute' the electical system. It protects from transient voltage and a massive OV. This may be the ticket if you want peace of mind, to protect your fancy EFIS. It is also has adjustable volts. Some electronics may be happier at say 12.8 volts than 14.5 volts, which just makes more heat. The only limit I can see is its good for only about 4 amps, so you might need two to protect all your expensive goodies. I might put it on my Comm, Intercom and EIS4000 engine monitor. My transponder is an older Collins with no voltage protection, so it might benefit from this device as well. My Dynon EFIS is suppose to be spike protected. I suppose this device would allow you to keep avionics on during start, which might be handy for engine monitors and EFIS. However I probably would continue to follow my practice of avionics off during start.

 

[Greg Arehart]

I would be interested to hear of anyone with personal experience with this. Sounds very useful.

greg

 

[Bevan]

power sag...

George,

Isn't the perceived problem for electronics during engine start is voltage sag (I call it brown-out) due to the large current draw of the starter? If so, this device, while good for smoothing power, wouldn't help much for a prolonged sag? I wonder how long of a voltage sag event this regulator could prevent from arriving at the avionics buss?

Bevan
Rv7A wiring

 

[gmcjetpilot]

Goo catch

George,

Isn't the perceived problem for electronics during engine start is voltage sag (I call it brown-out) due to the large current draw of the starter? If so, this device, while good for smoothing power, wouldn't help much for a prolonged sag? I wonder how long of a voltage sag event this regulator could prevent from arriving at the avionics buss? Bevan Rv7A wiring

You are right and I did not ask them this specific question. It does have a good size capacitor but now that you mention it, it probably is not enough to keep the lights lit during start? Good catch. I was just thinking of transient suppression, which they claim it does in spades.

 

[RV7Guy]

Interesting

Looks interesting but would like to hear from someone who has actually used one on a real airplane.

 

[AltonD]

http://www.miracleantenna.com/Smoothie.htm

Some electronics may be happier at say 12.8 volts than 14.5 volts, which just makes more heat.

OKay, I am going to lay it out there and argue with an engineer. The electronics might be happier at 12.8, I don't know. I would have to ask the OEM. but. . . Higher voltage makes less heat. Power loss is current squared times resitance. Power = volts X current. Higher voltage, less current, less power loss (heat).
This is why utilites run 500KV+ on distribution lines. Cuts their losses due to heating.

No flames, just my two cents.

 

[Jeff R]

Higher voltages can indeed mean higher power losses. If you are feeding something with 12 volts that is internally regulated to, say, 5 volts, the intenal voltage regulator has to drop 7 volts. Compare that if the input voltage is 24 volts, where it would have to drop 16 volts. If the voltage regulator is a linear one, and if the 5 volt current is 1 A, the voltage regulator power loss will be 7W with 12 volts, or a whopping 19 W with 24 volts. If a switching regulator is used, the losses in both cases will typically be much less, which is why switching regulators are so popular. But, Alton, higher voltages often make more heat.

Anyway, I am an EE who designs power supplies professonally, and this filter seems like all hype to me. There is no way that it can be a "brickwall filter", and I don't believe for one second that those oscilloscope displays depicted on the web site are an accurate representation of that filter.

 

[AltonD]

Anyway, I am an EE who designs power supplies professonally. . . .

I guess that settles it. Thanks for setting me straight.

 

[gmcjetpilot]

Another good catch

OKay, I am going to lay it out there and argue with an engineer. The electronics might be happier at 12.8, I don't know. I would have to ask the OEM. but. . . Higher voltage makes less heat. Power loss is current squared times resitance. Power = volts X current. Higher voltage, less current, less power loss (heat). This is why utilites run 500KV+ on distribution lines. Cuts their losses due to heating. No flames, just my two cents.

Alton, I hear you, I got it, but that is what the engineer guy said on the phone, just passing it on. I did not argue either (can you believe it). My ICOM does say 13.8 volts and my TDR950 transponder 14 volts, not 14.5 volts. As you say higher volts is more efficent. He may have been referring to the happiness of semiconductors with higher volts and life, not efficiency? Good catch though.

I am an EE who designs power supplies professonally, and this filter seems like all hype to me. There is no way that it can be a "brickwall filter", and I don't believe for one second that those oscilloscope displays depicted on the web site are an accurate representation of that filter.

Jeff, the way it was explained (and I did ask this two or three times) it protects from a steady-state gross over-voltage in a nut shell by sacrificial destruction of the capacitor, which in turn would blow the fuse/CB. During this melt down, if you will, the voltage regulator I was told would hold the voltage until the capacitor failed and popped the fuse/cb. What do you think? I asked if they tested it. I was told they did many intentional OV destruction tests.

This is why I put it up here Guys, to throw stones and darts at it.

 

[asav8tor]

30 years ago when I was in high school and college I worked at Radio Shack. We sold lots of stuff to; stop engine whine in your car stereo, eliminate static in your TV, demagnetize the head of your 8 track, etc. Much of the junk was a cure looking for a problem. Most of it did not work. Some of it came back for refunds but I suspect most of it got thrown in the garbage. Best case, that thing will probably do nothing for you; worst case it catches on fire and brings the plane down. Looks like $ 15 worth of non aerospace grade parts/construction.

 

[Jeff R]

As you say higher volts is more efficent.

No, that is not a universal truth. It is true for the transmission of power, but not in the consumption of power. This is why modern microprocessor development has been pushing voltages down from 5 volts, to 3.3 volts, then to 2.5 volts and now to 1.8 volts. It has to do with power losses. If you can drop the operating voltage by half, you have also dropped the power consumption by half for the same amount of current consumption. If "higher volts is more efficient", this trend would not be happening.

I suspect that the EFIS systems are using switching regulators to convert whatever standard aircraft DC voltage you provide it to the internal voltages that it needs in a very efficient manner. In this case, it doesn't make much difference what voltage you use in regards to power loss, however the unit may have a slighly longer life if you run it with voltages closer to the low end of the specifications, as switching regulators will generally last longer with lower voltages. If the EFIS uses internal linear voltage regulators, then the power losses will be much lower with a 12 volt system than a 24 volt system.

I agree that with a 24 volt system the I-squared-R losses in the aircraft wiring will be lower, but the losses in your avionics may be quite a bit higher , especially if linear voltage regulators are used therein.

Sorry to be beating this to death, but I love designing power supplies!

 

[David-aviator]

This is why I put it up here Guys, to throw stones and darts at it.

Not being an engineer it is my observation the device looks like a bunch of kids getting ready to celebrate at a birthday party....very cute and attractive presentation.

At the moment my Becker ATC 4401 transponder is with Becker in Miami being coaxed back to life. I have never started the engine with power to it but I always shut down before opening the avionics bus switch. Could it be the shut down is as harmful as the start up? The thing had been working fine for 4 years and suddenly went TU.

 

[Norman CYYJ]

The only reason that the solid state devices are using lower and lower voltages is because they are cramming more and more circuits closer together in the IC's and they need the lower voltages to prevent arc over. With the higher voltages things have to be spaced further apart. The thinner the dielectrics the lower the voltages must be. They use to make chips with a 1000 transistors on a square inch and that itself was a major feat not too many years ago, now with lower and lower voltages they are able to get millions of them. That is evident in the small ram chips we have as an example.

 

[Jeff R]

The only reason that the solid state devices are using lower and lower voltages is because they are cramming more and more circuits closer together in the IC's and they need the lower voltages to prevent arc over.

Yes, that and the fact that lower voltages greatly ease the cooling requirements. If you double the number of transistors, all other things being equal, you will double the heat. Also, if you double the operating frequency, you will also double the heat. Those closely spaced transistors may burn out from the heat before their dielectrics break down. If you can drop the voltage by half, you will also reduce the power losses by about half.

Still, my point was that lower voltages do not equate to higher power losses.

 

[gmcjetpilot]

Interesting mostly for Ultra Lights

I AGREE, with good grounds, quality electrical wiring and components (battery/alternator) our planes are quiet usually. Noise is just a symptom of problem. Filters like this mask the problem. If you don't need them, there is no reason to use it. If you want MORE transient or over voltage protection than you should start at the alternator and get a Plane-Power unit or externally regulated one with a Transpo V1200 regulator (1/3rd the price of a B&C with more capability).

The vendor did say the target market or use for this device was directed toward Ultra-lights, which typically have crude generating/regulation systems compared to our automotive based alternators.

Also modern avionics have better filters and discreet regulated power supplies, verses old radios, which took the supplied power right into the board and a 16 volt semiconductor. So damage was more likely with old stuff. That is why I still keep them off during start.

New avionics typically call for 10-30 volts supply, so it's already protected from some transients and OV in my opinion. Old radios, like one I have, says 16 volts will damage it. Not all new radios have internal regulated power supplies. The ICOM A200 can be damaged with +16 volts according to the manual and Tech Rep I talked to. The new ICOM Comm spec shows a wide input voltage capability, ie assume a regulated power supply. So even if you did blow the radio with some wild transient voltage, the damage should be limited to that power supply.

RV's have bigger alternators & batteries than ultra-lights, which "filters" out transients anyway, where an ultra-light's voltage is likely to be all over the place. This device may save the day for the ultra-light guys. Only some practical test in RV will tell its utility for our use.

I agree with Bob N., the key is to start with good grounds, good strong battery, good alternator and high quality wiring practices. We just disagree about internal regulation. Modern alternators, internal or external of any kind provide a clean (quite) voltage with reasonable OV protection.

It's not uncommon for a RV panel to cost $20-$30,000, so I understand the fear of OV, even if the fear is a little over blown. Most OV cases with little ND's, if they happen at all, are in the 16-17 volt range not 100's as some fear monger; this is well with in the modern avionics tolerance, eg, 10-30 volts, but not all avionics have a robust robust tolerance. However in theory stuff happens; never say never.

If you want more protection start with the basics, not individual line protection to discrete devices. However that may be an additional step if you want more insurance. This little device is a filter and does provide more isolation. The question of do you need it and how well does it work is up to debate.

What about lightning strikes? Military & airline stuff gets power through DC-DC power supplies. Kind of overkill for our mission, but lightning might take all your radios and EFIS out. I doubt this device was tested for lightning transient suppression, but it might help? I don't know.

If you have lots and lots of expensive stuff, a Plane-Power alternator or externally regulated alternator (B&C or homemade) with a Transpo V1200 regulator would be the first step I'd recommend, before any filters.

 

[Robert]

Response from Smoothie manufacturer

Greetings Gents...

George has reported quite accurately on our conversation of Friday - I thought I'd fill in some gaps.

Just before that, perhaps I should say that I've signed up here out of general interest in the Vans aircraft and won't be doing to much posting as I don't own one - I fly a Challenger 2LW - but this forum looks like a great place to lurk for good tech info and discussion of various issues.

Re power dissipation...

Lowering the input voltage to most gear will reduce its internal power dissipation and heating. A radio that specifies an input voltage range of 12-14 volts will run happier and cooler at 12v than 14v, and in many cases will operate very happily at 11v with even less heat and stress.

Re - Oscillographs...

These scans are straight off an RV-6 that was at our local field. The owner had problems with radio noise, and we only looked at the power supply after much fiddling with the radio. I was more surprised than anyone at the quality of the on-board power.

Re Brickwall...

The Smoothie uses a multistage approach. The first filtering stage is a CLC (pii) filter with a upper shelf that is 30dB down at 60 hz (under typical load). In english, no noise/ripple over about 40 hz gets through it.

The second stage is a low-dropout regulator with a lower shelf at around 3 kz - nothing below that gets through.

Between the two, nothing other than smooth, steady-state DC gets through.
The high-reactance inductor in the pii filter is like a massive magnetic shock absorber for any transients - they're simply soaked up through magnetic intertia. Smoothie absolutely works as we state it .


Re Radio Shack filters...

These (and many others you'll see on the market) are in fact often useless, as they are comprised of either a simple capacitor or a simple choke. While either may be effective in some very limited cases, they are heavily dependant on the source noise level, load impedance, source impedance and some other factors like construction and shielding.

We've designed Smoothie as we have to address and overcome the limitations of these cheaper filters. It's a 'get-what-you-pay-for' situation.

Re aerospace components...

Smoothie is not TSO'd but then I believe that's not an issue with exp aircraft. We use high-quality components, well engineered into a good design. Safety is very important in our design philosophy. Smoothie is protected against input over-voltage, over-temperature, and output overload or short circuit. We've destructively tested them repeatedly and never had a catastrophic failure.

The only failure mode that requires service is sustained over-voltage input beyond approx 19 volts. In this case the input capacitor (a physically robust unit) shorts out and crowbars the input, blowing the fuse. Any other out-of-range condition merely causes the LDO regulator to shut down. Note that Smoothie is NOT internally fused but is specified to be supplied via a fused or breakered input.

Re do you need one...

I agree that an aircraft's DC power system should be properly engineered, constructed and maintained such that power-supply noise is not an issue. That's in a perfect world. In reality aircraft ageing, the less-than-perfect original layout of wiring, grounding and shielding, and the addition of some newer gear with rather poor power-supply designs can all contribute to winding up with some hard-to-cure DC noise problems.

While NASA might tear the whole thing apart and start from scratch to address the problem, (or might not, come to think of it) not every pilot wants to go this route when there are more practical and effective ways of solving the problem.

Even when everything is perfect, some digital units like GPS, Zaon, EIS, etc and strobes can create DC pollution that the original system was never designed to absorb. The engineers here on this list will conclude that the proper design approach to retrofit any such power supply to cope with such a problem would be to include a noise-filtering stage that operates exactly as Smoothie was designed to do.

Re hearing from actual users...

List members are invited to contact us directly and we'll provide these many references.

Thanks for the opportunity to comment. I invite anyone who wishes more info to contact us toll-free 866 311 6511

Best regards - Robert Victor (Miracle Antenna)

 

[az_gila]

Low voltage level and older radios

Greetings Gents...

George has reported quite accurately on our conversation of Friday - I thought I'd fill in some gaps.
.........
Lowering the input voltage to most gear will reduce its internal power dissipation and heating. A radio that specifies an input voltage range of 12-14 volts will run happier and cooler at 12v than 14v, and in many cases will operate very happily at 11v with even less heat and stress.
......

Best regards - Robert Victor (Miracle Antenna)

Robert, this statement is not always true for older electronics... if you check with your local glider pilots, you will find that many use an extra 2 volt gel cell attached to their 12 volt gel cell to keep the voltage up (no charging system......)

A lot have found that German radios have a lower Tx current draw and better low voltage ability than the US radios built for aircraft with large batteries and a functioning alternator - that's why my sailplane has a Dittel radio and a 12 volt gel cell.

If you want to cut voltage to your older electronics, then you should run some careful tests at differing voltages in the high current draw mode (usually transmitting) and then build a bit of a safety margin in...

I can't say for sure, but would guess more modern radios have better input power supplies (and probably switching ones) and would run at lower voltages...

gil A

 

[Robert]

Lower Voltage-Older radios

Hello Gil...

I agree with your comments. Older radios can be much more voltage sensitive in terms of stability and output power - they like the full 13.8 volts.

In almost any newer design (past ten years (at least)) the internal electronics are working at a much lower voltage than this; the supply voltage is regulated down either en-masse or stage-by-stage to some lower value. All the digital sections - memory, VFO, etc are running at 5 , 3.2 or less. The bulk of the analog will be running at 5-9 volts. The RF output stage may be higher, including supply voltage.

Reducing input voltage, or at least keeping it at the low end of the spec'd input range, will reduce the power dissipation in the internal regulators which can amount to a significant reduction of heat - always the enemy.

When the RF output stage is running at the full input voltage, reducing the voltage will reduce RF output power. A drop of 50% in the output power will reduce your signal strength by 3B on the other end of the transmission, which is just barely perceptible. It's a good trade-off - if the other elements of your system such as antenna, audio system, power-noise, etc are in good shape, you'll still reach the horizon every time and do so running your radio much cooler.

As you say, when in doubt, test.

The trend in radios remains series-pass rather than switching regulators. Switching regulators are prone to generate a lot of noise, some of which winds up in the various pass-bands and creates interference. Even external switching supplies create interference, as can other digital gear running off the same supply lines. This is the one and only reason the Smoothie uses a series-pass regulator rather than a switching type.

Best regards - Robert

 

[Mike S]

Greetings Gents...

Just before that, perhaps I should say that I've signed up here out of general interest in the Vans aircraft and won't be doing to much posting as I don't own one - I fly a Challenger 2LW - but this forum looks like a great place to lurk for good tech info and discussion of various issues.

Robert Victor (Miracle Antenna)

Hey we dont care what you fly, you are more than welcome here.

As to your comment about it being a good place for tech info, and discussion----O boy, is that a bit of an understatement.

Welcome aboard.

By the way, let me caution you about taking a ride in a RV, should someone offer you the chance. It could end up costing you a bunch of $$$$$.

Demo flights in an RV are often called the $50,00 free test ride.

 

[vlittle]

... If you can drop the voltage by half, you will also reduce the power losses by about half.

Still, my point was that lower voltages do not equate to higher power losses.

Actually, a strong component of power dissipation in IC's is related to the square of voltage, so reducing the voltage by half will reduce power to 1/4 (in general).

This is due to frequency related capacitive dissipation which is 1/2*f*C*V^2.

Thus proving that I too speek geek!

 

[Jeff R]

Actually, a strong component of power dissipation in IC's is related to the square of voltage, so reducing the voltage by half will reduce power to 1/4 (in general).

This is due to frequency related capacitive dissipation which is 1/2*f*C*V^2.

The V-squared thing works for resistive loads, where P=V^2/R, but note, too, that P=VI. If the current draw stays the same, then reducing the voltage by half will reduce the power by half. The equation you quote gives the amount of energy stored in a capacitor, not its power dissipation (which depends on it equivalent series resistance).

As for the filter, we are gents here, so I will just make a few more comments.

I feel calling the filter a "brickwall" filter is a bit misleading. A 3rd order filter is a long way from being a brickwall filter, though 3rd order filters are fairly common in power filters. Some of my filters are 5th order, but I would never claim them to have a brickwall rolloff.

I guess before I will comment any more on the oscillograms, I would need to know what the scope settings were. Showing a dual trace picture of the input and the resulting output (and showing the scope settings) would be very useful. Showing two traces without knowing the scope settings, and seeing the output without knowing what the input was that produced that output, is not very useful and invites skepticism.

Finally, I am concerned that some people might get the idea that if they regulate their bus voltage of 14 volts down to 12 volts with a shunt regulator, they will reduce the power dissipation of their avionics. No! All they will do is burn up power in the regulator. If you drop 2 volts in a shunt regulator to an instrument that needs 4 A, you would burn up 8 W for nothing.

 

[Robert]

Hello Jeff...


"I feel calling the filter a "brickwall" filter is a bit misleading. A 3rd order filter is a long way from being a brickwall filter"

You're forgetting the following series-pass regulator. It's pretty much an absolute brickwall for anything up to several khz. It's certainly no 3rd nor 5th order filter. We're quite happy with the nomenclature.


"I guess before I will comment any more on the oscillograms, I would need to know what the scope settings were. "

I can be as skeptical as the next guy when it comes to advertising. These images are given as recorded - power in, power out, same scale both sides. Put a scope on your own system - you might be surprised.


"Finally, I am concerned that some people might get the idea that if they regulate their bus voltage of 14 volts down to 12 volts with a shunt regulator, they will reduce the power dissipation of their avionics. No! All they will do is burn up power in the regulator. If you drop 2 volts in a shunt regulator to an instrument that needs 4 A, you would burn up 8 W for nothing."

I disagree with this. Keeping the supply voltage for almost any gear at the lower end of its specified range will reduce current, save power and minimize heating. Devices that don't behave this way are exceptional.

Yes, some dissipation can be shunted to the supply, but the overall total will be less, and the supply - Smoothie in this case - is designed to handle it without stress. Please note that it's a series-pass regulator, not a shunt as you state.

Thanks for your comments -

-Robert

 

[Jeff R]

Robert,

For me to comment more without having tested your device would not be proper, though as a designer of power supplies used in military avoinics, I stand by my statements. Heck, if the claimed performance is true, let's talk a licensing deal, as your solution would solve a bunch of EMI problems!

 

[Robert]

Smoothie...

Hi Jeff..

As per your quote below, I say, "Exactly!"

If you'd like to talk about applying the design somewhere, feel free to reach me at our toll-free number at your convenience - 866 311 6511.

Regards - Robert



"if the claimed performance is true, let's talk a licensing deal, as your solution would solve a bunch of EMI problems!"

 

[vlittle]

The V-squared thing works for resistive loads, where P=V^2/R, but note, too, that P=VI. If the current draw stays the same, then reducing the voltage by half will reduce the power by half. The equation you quote gives the amount of energy stored in a capacitor, not its power dissipation (which depends on it equivalent series resistance)...

In a CMOS integrated circuit, energy is dissipated primarily by charging/discharging interconnect and gate capacitance. The formula I provided reflects this, and it is proportional to voltage squared. If anyone really cares, check this link http://www.ece.iit.edu/~velenis/courses/fall2006/ece530/Presentation/HiranmayVennelakanti.ppt

This is why computer chips like to run at low voltages, keeping their power dissipation low.

Vern

 

[Bubblehead]

Why keep power on avionics during shutdown?

At the moment my Becker ATC 4401 transponder is with Becker in Miami being coaxed back to life. I have never started the engine with power to it but I always shut down before opening the avionics bus switch. Could it be the shut down is as harmful as the start up? The thing had been working fine for 4 years and suddenly went TU.

David - is there a reason to keep power to avionics when you shut down? I think most or all operating handbooks say shut down all electrical circuits before shutting down the engine. I just checked T-210, M-231 and C-172 POHs and they all say to turn off avionics power before shutting down the engine.

It just seems like good practice to remove as many electrical loads as possible from the system before shutting the engine down. This also isolates expensive, sensitive electronic equipment from what ever transients may come down the pike during the shut down.

 

[gmcjetpilot]

Because

Thanks for your comments - -Robert

Robert Thank you for your comments. Your welcome to post anytime and you don't need to have an RV. Your a pilot and you have personal expertise and interests in subjects relevant to building. Your input is welcomed anytime about any topic. Thanks again.

David - is there a reason to keep power to avionics when you shut down?

Because someone (who will remain nameless, present company excluded) will tell you your wrong and dumb in a manifesto 5 times longer than my longest post (which is long). Ha-ha, I'm kidding. There is every reason to follow the AFM. I'm an on after start, off before shut down kind of guy. Cheers.