Today's Message Index:
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1. 04:33 AM - OFF-WHITE x Nike Air Max 90 Desert Ore is Available Now (blair2019)
2. 07:19 AM - EE needed (tomcostanza)
3. 08:46 AM - Re: EE needed (Robert L. Nuckolls, III)
4. 08:51 AM - Re: EE needed (Robert L. Nuckolls, III)
5. 08:51 AM - Re: EE needed (user9253)
6. 09:03 AM - Re: EE needed (user9253)
7. 10:02 AM - Re: EE needed (tomcostanza)
8. 10:10 AM - Re: EE needed (tomcostanza)
9. 10:14 AM - Re: Re: EE needed (Charlie England)
10. 11:17 AM - Re: EE needed (tomcostanza)
11. 01:54 PM - Re: Re: EE needed (Robert L. Nuckolls, III)
12. 04:58 PM - Re: EE needed (user9253)
13. 05:05 PM - Re: Re: EE needed (Alec Myers)
14. 08:50 PM - Re: Re: EE needed (Robert L. Nuckolls, III)
Message 1
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Subject: | OFF-WHITE x Nike Air Max 90 Desert Ore is Available |
Now
Nike Sport Sneakers (https://www.cadysneakers.com) has released the black and white Air Force 1 that has just been released in his personal Instagram Story, and notes that the cooperation between OFF-WHITE and Nike seems to be coming to an end. Overnight, in the fermentation of the news and the speculation of the fans, the prices of many shoes in the past have taken off in the resale market. Such a real reaction is not only reminiscent of "every pair of shoes that have been released since then, may be the joint end of the work." Recently, the OFF-WHITE x Nike Air Max 90 Desert Ore color scheme, which has been released many times, is finally coming to the market with great attention. The first pair of New Year's shoes in the Air Max 90 wheat color scheme is paired with this year's popular color "Coral Orange" and light blue. The iconic Swoosh Logo and the heel deconstruction, the upper and the tongue are made of nylon, and the rest are made of suede. In general, it is still a pair of shoes with the combination of OFF-WHITE x Nike. The upper foot effect will be very good and worth looking forward to. It is worth mentioning that this time, like the OFF-WHITE x Air Force 1, the children's shoes will be sold in the same period. The overall design is basically the same as the adult model, and the feeling of roundness is very cute. If you have a baby, you can prepare a pair in advance. If you don't have it, you can buy it as a small key chain. It is very delicate!
At the end of last year, Air Jordan 11 "Concord" returned to the game after seven years. It was absolutely shocking to the whole sneaker circle. In order to express a tribute to these shoes, all the stars also got on the Air Jordan 11 various PE color matching, Drake more I personally got a pair of ultimate goods! Since Drake and Jordan Brand have returned to last year, they have started to play a variety of PE color matching, which definitely makes a lot of sneaker players envious. Unlike the Air Jordan 11 Low Green Snake and Powder versions, the Air Jordan 11 Snakeskin (https://www.nikysport.com/product-category/air-jordan-11-sneakers/) uses OG high-top shoes. The iconic black patent leather is rendered in crepe leather, and the visual performance is more luxurious and elegant. From the specifications of light blue outsole and large patent leather, it is definitely the product born last year.
First exposed on Monday, the Air Jordan Retro 1 High OG Crimson Tint (https://www.sportjordans.com/index.php/product-category/air-jordan-1/) in front of this pair of ice cream is not a small concern, and today released a new physical picture! Pink theme Air Jordan 1 is quite rare in our impressions. The last time it appeared or was released on the yacht of the Basel Art Show in 2017, the dirty powder AJ1, due to the scarce quantity, has now exceeded the 20,000 yuan mark. This pair of shoes with black lychee skin with a refreshing nude powder, simple white background, and finally the same color of the pink outsole. Although it is OG's nine-hole shoe type, but the traditional retro temperament, the bright color of the creation, showing a bright and vibrant atmosphere, I believe that the eye-catching index will not be low!
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Message 2
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This is a non-aviation question so please forgive my blatant request for info.
I have a solenoid rated as follows: 12VDC 29mA 4.0W (printed on the coil). I
don't have any more information about it.
I need to open it for a VERY short time (around 30ms), then let its spring close
it. If I just apply 12VDC for 30ms, it barely has time to open and I get inconsistent
results. So:
1) Being an inductor, it's opposing the change in current in the 1st place.
2) It barely overcomes that, and then the current goes away.
I'm thinking I can apply much more than 12V with a proportional increase in current,
since it's only for 30ms, but don't know how to figure out how much for
how long. I would very much appreciate someone giving me a non-differential equation
answer if there is one.
Give a man a fish and you feed him for a day. Teach a man to fish and you feed
him for a lifetime.
Thanks so much.
--------
Clear Skies,
Tom Costanza
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Message 3
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At 09:19 AM 1/12/2019, you wrote:
><Tom@CostanzaAndAssociates.com>
>
>This is a non-aviation question so please forgive my blatant request for info.
>I have a solenoid rated as follows: 12VDC 29mA 4.0W (printed on
>the coil). I don't have any more information about it.
29mA? That's only 0.35 watts. Could it be 290mA?
What's the physical sized of this device. 4W dissipated
into a small mass gets pretty hot in a hurry.
>I need to open it for a VERY short time (around 30ms), then let its
>spring close it. If I just apply 12VDC for 30ms, it barely has time
>to open and I get inconsistent results. So:
>1) Being an inductor, it's opposing the change in current in the 1st place.
>2) It barely overcomes that, and then the current goes away.
Yup. How critical is the timing for being 'active'?
What are the tolerances on that 0.030 seconds?
You could build an adjustable pulse generator that
would be tailored to produce the pulse length needed
to achieve the 0.030 second activation requirement.
>I'm thinking I can apply much more than 12V with a proportional
>increase in current, since it's only for 30ms, but don't know how to
>figure out how much for how long. I would very much appreciate
>someone giving me a non-differential equation answer if there is one.
What voltages are available in your system.
Inductive time constant is t=L/R. One way
to get smaller T is increased R. We used
to speed up response time on stepper motors
with big resistors in winding leads . . . wastes
a lot of POWER but for our needs, response time
was critical, warming up the room not so much.
>Give a man a fish and you feed him for a day. Teach a man to fish
>and you feed him for a lifetime.
There are also some constant current generator
circuits that might be more attractive . . .
but they still toss off a majority of the
power.
The adjustable pulse width generator might be
the first thing to try.
Bob . . .
Message 4
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The adjustable pulse width generator might be
the first thing to try.
See https://tinyurl.com/y92d76o4
Bob . . .
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When you say open and close, I assume that you are talking about a valve or
something, not the electrical circuit.
You wrote "but don't know how to figure out how much for how long". It seems
that you are able to vary the time. So instead of increasing the voltage, why
not just increase the time?
Are the current or watts correct? Looks like something is off by a factor of
10.
I calculate 69 volts.
E x E = 33.3 x 12 x 12
E = 69 volts
Hopefully someone will correct me if wrong.
--------
Joe Gores
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Message 6
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I should have posted 69 volts maximum for 30 milliseconds. The actual voltage
to get the desired results can be determined by trial and error.
--------
Joe Gores
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Message 7
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Bob,
> 29mA? That's only 0.35 watts. Could it be 290mA?
> What's the physical sized of this device. 4W dissipated
> into a small mass gets pretty hot in a hurry.
I noticed that as well. But that IS what's printed on the coil. FYI, it's about
1"x1"x0.75"
> How critical is the timing for being 'active'?
> What are the tolerances on that 0.030 seconds?
The timing is the only thing that IS critical. It's a project of my own design,
so I can vary just about anything.
> What voltages are available in your system.
> Inductive time constant is t=L/R. One way
> to get smaller T is increased R.
As I said, I can vary just about anything. But wouldn't adding a resistor in series
just further reduce current and exacerbate the problem?
> The adjustable pulse width generator might be
> the first thing to try.
Again, I can vary the drive to the solenoid any way I want, and can set the pulse
width to whatever I want. But what voltage/current would I use for the pulse?
TI makes a chip (DRV110) that does just what I want, but I suspect it's designed
for longer engage/hold times. My short t is what's screwing it up.
--------
Clear Skies,
Tom Costanza
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Message 8
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user9253,
I didn't understand your calculation.
I calculate 69 volts.
E x E = 33.3 x 12 x 12
E = 69 volts
Where does 33.3 come from?
If I use the 4W number:
V = P/I = 4/0.029 = 137V
But for how long? Obviously 137V through a 12V coil would let the magic smoke
out in very short order.
--------
Clear Skies,
Tom Costanza
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Message 9
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On 1/12/2019 12:01 PM, tomcostanza wrote:
>
> Bob,
>
>
>> 29mA? That's only 0.35 watts. Could it be 290mA?
>> What's the physical sized of this device. 4W dissipated
>> into a small mass gets pretty hot in a hurry.
>
> I noticed that as well. But that IS what's printed on the coil. FYI, it's about
1"x1"x0.75"
>
>
>> How critical is the timing for being 'active'?
>> What are the tolerances on that 0.030 seconds?
>
> The timing is the only thing that IS critical. It's a project of my own design,
so I can vary just about anything.
>
>
>> What voltages are available in your system.
>> Inductive time constant is t=L/R. One way
>> to get smaller T is increased R.
>
> As I said, I can vary just about anything. But wouldn't adding a resistor in
series just further reduce current and exacerbate the problem?
>
>
>> The adjustable pulse width generator might be
>> the first thing to try.
>
> Again, I can vary the drive to the solenoid any way I want, and can set the pulse
width to whatever I want. But what voltage/current would I use for the pulse?
>
> TI makes a chip (DRV110) that does just what I want, but I suspect it's designed
for longer engage/hold times. My short t is what's screwing it up.
>
> --------
> Clear Skies,
> Tom Costanza
>
>
Details would help a lot. Solenoid controlled valve, or relay? If relay,
what voltage, current, and AC or DC?
If it's a relay, replacing it with something solid state would simplify
your problem by quite a bit.
Charlie
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Message 10
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Some more data points:
I have several of these devices from 3 "manufacturers"
Vendor Written on device
Measured
-------------------------------------------------------------
1 12V 2.5W
22 ohms 440mA
2 12V 5W
35 ohms
320mA
3 12V 29mA 4.0W
35 ohms 320mA
So it seems Bob's question about "is it really 29ma" was exactly right. The coil
is sealed, so I can't even guess about the wire size.
I guess I don't have enough info to solve this mathematically, so I'll have to
do it empirically.
Thanks to all for their input.
--------
Clear Skies,
Tom Costanza
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>
>I guess I don't have enough info to solve this mathematically, so
>I'll have to do it empirically.
Too many unknown variables. From the time it's energized
to the instant that full travel is realized has a lot of
variables only slightly related to the t=L/r rise.
Putting an adjustable pulse generator in the loop
will let you 'dial in' a pulse width that achieves
the desired effect.
Bob . . .
Message 12
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I assumed, maybe incorrectly, that 1 full second is the maximum amount of
time to apply high voltage without damaging the coil. One second divided by 30
milliseconds equals 33.3
Watts = E squared / R
Power at high voltage for 33 milliseconds = power at 12 volts for 1 second
E squared / (33.3 x R) = 12 volts squared / R
The Rs cancel.
Thus E squared / 33 = 12 squared
E x E = 33.3 x 12 x 12
E = 69
Maybe my reasoning is flawed, but 69 volts will cause less smoke than 137 V.
:-)
--------
Joe Gores
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Do you think trying to activate a coil for so short a period with a timed pu
lse is reliably repeatable over variations in temperature etc?
What if the supply voltage has variations?
Or the spring in the relay changes elasticity as it ages?
Hate to be a pooper but maybe an approach with solid state switching would b
e more reliable?
Sent from my iPhone
> On Jan 12, 2019, at 16:53, Robert L. Nuckolls, III <nuckolls.bob@aeroelect
ric.com> wrote:
>
>>
>> I guess I don't have enough info to solve this mathematically, so I'll ha
ve to do it empirically.
>
> Too many unknown variables. =46rom the time it's energized
> to the instant that full travel is realized has a lot of
> variables only slightly related to the t=L/r rise.
> Putting an adjustable pulse generator in the loop
> will let you 'dial in' a pulse width that achieves
> the desired effect.
>
>
> Bob . . .
Message 14
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At 07:05 PM 1/12/2019, you wrote:
>Do you think trying to activate a coil for so short a period with a
>timed pulse is reliably repeatable over variations in temperature etc?
Your automobile's fuel injector
valves do it . . .
>What if the supply voltage has variations?
>
>Or the spring in the relay changes elasticity as it ages?
>
>Hate to be a pooper but maybe an approach with solid state switching
>would be more reliable?
Those are some of the variables I
cited. Fuel injected engines have
the advantage of being able to monitor
mixture in real time and adjust
pulse width and timing to maintain
design goals irrespective of a
constellation of intervening
variables.
Your concerns for maintaining
consistent solenoid behavior
'open loop' are valid.
But we don't know tolerance to which
the behavior is expected. It may be
that once the t=L/R factor is
accounted for, the rest of them
are operationally insignificant.
It may be that the 'desired behavior'
can be measured and used to close the
loop on a variable pulse width generator.
Bob . . .
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