Help me solve this design problem PLEEEZ

[Mark Jones]

John Fields wrote:

5 minutes is a little long for a 555, and 24 bits is a little much,
IMO, but a successful marriage might be a single 555 astable with a 20
second period and a 4 bit up-down counter.


Then,



---
No problem, just pricey. $49.78 from Farnell, (if they had any) plus
the crystal and the oscillator and the glue logic.

Use a 7555, something like an HC193 and the glue logic needed to make
it work the way the OP wants it to, and you're talking probably less
than $5 for the whole thing.

Even less than that would be a cheap 8 bit µC, and all you'd need
there would be the micro and a 32768Hz crystal. Plus, if he wanted to
do temperature instead of (or in addition to) time, a micro with an
external temp sensor (LM71) would do it.

And what about the learning curve? Does the OP have any experience with PICs?
How long is it going to take to get that chip programmed and debugged
successfully? Sure PICs are handy, but they are not simple "jellybean" parts. We
all know that you know everything John, but the rest of us have to work hard at it.

 

[John Fields]

And what about the learning curve? Does the OP have any experience with PICs?
How long is it going to take to get that chip programmed and debugged
successfully? Sure PICs are handy, but they are not simple "jellybean" parts. We
all know that you know everything John, but the rest of us have to work hard at it.

---
I notice from your post on "Stop Light Design" that you're no stranger
to PICs, and you went ahead with what you considered a valid solution
with, it seems to me, little regard for the learning curve or the OP's
experience with PICs or the length of time it was going to take to
debug your code and program the chip, so what's got your knickers in a
bunch this time? Perhaps because I had the temerity to post a better
solution than your dual 555 mess on this thread? Perhaps because I
suggested a µC before you did? Who knows, and more importantly, who
gives a shit.

Oh, and before I forget: **** you, Jones, and have a nice April 1st!

 

[mike]

This is not really a "design" problem yet. What voltage is being
switched onto that solenoid and what kind of access do you have to it?
And you have several things going on here like that 50% maximum limit
applies for on times of 5 minutes but can be higher for lesser on times?
Or do you want a timer that locks out the solenoid for a duration equal
to the preceding on time? Or is the timer to alarm when the operator
exceeds previous off time or 5 minutes whichever comes first? If duty
cycle is the main thing then a simple timer will not be enough.

What does the electromagnet do?

I have a vision of a crane with an electromagnet lifting tons of stuff.
IF that's the case, you DO NOT EVER WANT TO INTERFACE WITH THE MAGNET IN
ANY WAY!!!
You build a device to supply information into the operator's decision
process. Even inhibiting the "on" button can cause you legal grief
if the magnet is needed in an emergency and it don't work because of you.

Last thing you want is a ton of steel falling out of the sky 'cause you
turned off the magnet...no that's the second to last thing.
Last thing you want is an injury accident traced to something with which
you were even peripherally associated.

If temperature is the issue, that's what you should be measuring.

If we're talking about a hand-held tape demagnetizer...never mind...

mike, AKA Dumbass


--
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..
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MAKE THE OBVIOUS CHANGES TO THE LINK
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[Fred Bloggs]

What does the electromagnet do?

I have a vision of a crane with an electromagnet lifting tons of stuff.
IF that's the case, you DO NOT EVER WANT TO INTERFACE WITH THE MAGNET IN
ANY WAY!!!
You build a device to supply information into the operator's decision
process. Even inhibiting the "on" button can cause you legal grief
if the magnet is needed in an emergency and it don't work because of you.

Last thing you want is a ton of steel falling out of the sky 'cause you
turned off the magnet...no that's the second to last thing.
Last thing you want is an injury accident traced to something with which
you were even peripherally associated.

If temperature is the issue, that's what you should be measuring.

If we're talking about a hand-held tape demagnetizer...never mind...

mike, AKA Dumbass

Looks like the "funster" done evacuated the area when pressed to give
the real meaning of the 50% and 5 minute interval- so not a critical
application, probably something like a solenoid to release air blast to
load Batman underwear into a package...

 

[Mark Jones]

---
I notice from your post on "Stop Light Design" that you're no stranger
to PICs, and you went ahead with what you considered a valid solution
with, it seems to me, little regard for the learning curve or the OP's
experience with PICs or the length of time it was going to take to
debug your code and program the chip, so what's got your knickers in a
bunch this time? Perhaps because I had the temerity to post a better
solution than your dual 555 mess on this thread? Perhaps because I
suggested a µC before you did? Who knows, and more importantly, who
gives a shit.

Oh, and before I forget: **** you, Jones, and have a nice April 1st!

I never said a PIC was an easy solution, where you did - that is the
difference. PICS ARE NOT SIMPLE DEVICES - except if John Fields is using them,
since he's the world's biggest know-it-all. Furthermore, a stoplight program is
trivial compared to a 50% duty cycle/temperature integration program. I couldn't
care less about your bloated ego, sorry. Only females should be put on a
pedistal, and even then, pedistals are still a bad thing. Are you implying
you're a woman? Or that you just want to be treated like one?

 

[John Fields]

I never said a PIC was an easy solution, where you did - that is the
difference.

---
Really? If you can show where I said that a PIC was an easy solution
I'd appreciate seeing it. What I thought I said was that a µC would
be a less expensive solution, in terms of the hardware required to do
the job, and I don't think you can dispute that.
---

PICS ARE NOT SIMPLE DEVICES - except if John Fields is using them,
since he's the world's biggest know-it-all.

---
I never said that microcontrollers are simple devices to work with,
(even though they are, once you get the hang of it) but you seem to
have a problem with the fact that I can solve problems in ways which
you disapprove of.

Why would that be? Are you jealous or something? Do you feel
intimidated because I have no qualms about suggesting relays when
that's what's needed, or embedded microcontrollers if that'll get the
job done?

It seems to me that you're disgruntled because I pooh-poohed your dual
555 "solution" for the OP's problem and, like a petulant child, are
having a hissie-fit trying to get me to kow-tow to you by casting me
in the role of an ogre. It ain't gonna happen, asshole, so you might
as well knock off the crap and get down to specifics, if you can.
---

Furthermore, a stoplight program is
trivial compared to a 50% duty cycle/temperature integration program.

---
So, since in one sentence you're admitting that a 50% duty
cycle/temperature integration program isn't trivial, are you saying
that considering a µC might be the way to go?

It seems to me that that's one of the choices I enumerated earlier,
and what you seem to be in disgreement with. In the light of that,
can you justify your seemingly waffly position?
--

I couldn't care less about your bloated ego, sorry.

---
And yet you choose to post that you don't care? If you truly didn't
care you'd remain silent.
---

50% duty cycle/temperature integration program, and even then,
pedistals are still a bad thing. Are you implying
you're a woman? Or that you just want to be treated like one?

---
Somehow, I seem to have lost track of the thread but, if you want to
talk about pedestals and women, I'll suggest that your mother took the
position that, since she couldn't possibly win in a physical
confrontation with your father and he wanted her in a sexual way,
after the initial coupling she went for withholding sex (while
pretending to be vulnerable) in order to gain her objectives.

Unfortunately, it seems that in your case you've been taught and abide
by "If I want some pussy I've got to play by her rules".

Oh, well...

 

[Mark Jones]

That's the first truly intelligent thing you've said since sticking your head
out from between your mother's legs (and gasping for air.)

To think, you resorted to cutting down my mother with childish slander. How old
are you again? Ego get a boost there? Johnnie boy, hehe, grow up. So far all
you've done is proven your ego-centricity and childishness. Yeah, you might know
quite a bit about electronics, but you're still an arrogant, egocentric,
childish jerk. Chew on that for awhile. Don't expect a reply; apparently I'll be
busy scrogging/felching my mother.


-- "When the world collectively arrives at the mindset that war is pointless,
perhaps we'll finally earn our GED from this school of life and go about living
it proper." MCJ 20050302

 

[keith]

On Sat, 02 Apr 2005 10:37:52 -0500, Mark Jones wrote:

Ok, I'll wade in, but only so far. ;-)

I never said a PIC was an easy solution, where you did - that is the
difference. PICS ARE NOT SIMPLE DEVICES -

Of course they are. That's the whole point of PICs. They *ARE* simple.

except if John Fields is using them,

No, "except if you recommend them".

since he's the world's biggest know-it-all. Furthermore, a stoplight program is
trivial compared to a 50% duty cycle/temperature integration program.

Oh good grief. The difficulty in any new uC is learning the tools and
building the first trivial program (why I like attaching blinkin' lights).
Once the tools hurdle is crossed either of the above problem becomes
trivial. I've never used a PIC, but wouldn't hesitate to jump in there if
I ever had a need for a *simple* embedded processor.

The fact is that *you* think PICs are somehow difficult, which says a lot
for your skills.

I couldn't
care less about your bloated ego, sorry. Only females should be put on a
pedistal, and even then, pedistals are still a bad thing.

Women should be, so? They *are* the mothers of our children.

Are you
implying you're a woman? Or that you just want to be treated like one?

You are inferring a lot! ...again saying more about you than John.

 

[Franc Zabkar]

There is an electromagnet at my job that has a 50% duty cycle. That is
it may be on for up to 5 minutes and then off for 5 before using it
again. I want to design a circuit that acts as a time integrator. As
long as a relay is pulled in, the timer is counting up. When the relay
is out, the timer counts down to zero and stays there. If the operator
isn't paying attention, and he goes over 5 minutes, an alarm sounds to
alert him that he is operating the electromagnet outside its design
parameters.
How can this be accomplished? Any suggestions would be appreciated.

If you want to try a micro, then consider a PICAXE. This is a PIC with
on-chip BASIC. No need to learn assembler. A PICAXE can cost as low as
$3.


- Franc Zabkar

 

[John Fields]

That's the first truly intelligent thing you've said since sticking your head
out from between your mother's legs (and gasping for air.)

---
That's according to who? You? LOL, you can't even admit that a
solution you condemned when I offered it is precisely the same
solution you offered earlier _with code_ attached! Sound hypocritacal
to you? I does to me. Not too smart either.
---

To think, you resorted to cutting down my mother with childish slander. How old
are you again?

---
Sixty-seven. And you? 14 or so?
---

Ego get a boost there? Johnnie boy, hehe, grow up. So far all
you've done is proven your ego-centricity and childishness.

---
On the contrry, I've proven that you're a blowhard with an extreme
reticence to accept constructive criticism and a taste for
self-deception.
---

Yeah, you might know quite a bit about electronics,

---
Which seems to just bug the shit out of you for some reason. Perhaps
you feel that being corrected by an old reprobate like me is beneath
your dignity, and you whine on, ad nauseam, so you can try to fool
yourself into thinking that I was wrong and you were right. If you
want to do something constructive, prove I was wrong technically or
apologize for being a horse's ass and shut the **** up.

 

[bigolow]

You did not tell us who or what turns on the relay and turns it
off. If controlled by a microcontroller, then it could easily be
programmed to count down to zero. If it is the operator that
performs this function then the timing would not be precise.

Having said that, you could use a timer circuit (555) that is
started by the action of the relay switch and times out after 5
minutes. It will then drive the alarm if not reset by the action of
the relay switch (Operator).

Hope that this helps.

 

[petrus bitbyter]

Thanks all... Wow... the talent out there is amazing. And to think
that my company was quoted from an engineering company to do the job
for $30,000. The circuit I named was just the most basic one possible
though. They would have added a recorder and a signal sent up to
supervision when the operator violated the %50 duty cycle requirement.
Keep the suggestions coming though and you may have earned a promotion
for me. LOL

Well,

That $30,000 looks pretty much to me. But on the other hand, there certainly
*has* some work to be done. Customized solutions tend to be expensive.

Let's recapitulate. Somewhere some operator has to activaty some equipment
and starts it. Some detector finds out and some clock starts to tick. After
five minutes the clock raises some alarm while continuing ticking. Some
operator deactivate the equipment. Some detector finds out and the clock
start to tick in the reverse while signaling somehow that the equipment
should have been to leave alone until the clock is back on its starting
point. It should be nice to also raise the alarm when someone activates the
equipment during that period.

Be aware that the principle is not very interesting from an engineering
point of view. As we have lots of sheep electronics these days, an
electronic solution seems the best. Half a century ago one would use some
relays, switches and a small motor for instance.

But some tasks has to be done for every solution. You have to find out how
to sense that the equipment is on. Decide what components you need, build
the detector and find a way to install it. No need to say it has to be safe
and reliable. Most of this part of the design depends on information you did
not provide. So do the costs.

On the output side you need some alarm. Both audible and visual components
are available in wide ranges and versions. You have to decide what satisfies
your needs and how and where it has to be installed. The same counts for the
signaling whether or not the equipment is ready for use.

Now you need some processing unit, the clock. Whatever you build, you will
need some power supply, some chassis or PCB and an enclosure for it.

My choice would be to buy some of the shelf enclosure. As I need only one of
a kind, I would use some prototyping PCB with a micro - an eight pins PIC or
AVR will do - two signaling LEDs and a driver for the audible alarm. The
latter can find a place in the enclosure as well along with some input jack
to connect the on/off sensor. I can do so while I have the skills and
equipment to program the micro. As for the power supply I would use an off
the shelf 5V wall wart.

Note that allthough $30,000 is still pretty much, you will for sure need
some thousends to get this all done by a professional.

petrus bitbyter

 

[petrus bitbyter]

Be aware that the principle is not very interesting from an engineering
point of view. As we have lots of sheep electronics these days, an
electronic solution seems the best. Half a century ago one would use some
relays, switches and a small motor for instance.

<snip>

sheep electronics are really cheap these days

petrus bitbyter

 

[Terry Given]

<snip>

sheep electronics are really cheap these days

petrus bitbyter

They give androids something to dream about.

Cheers
Terry

 

[Spehro Pefhany]

They give androids something to dream about.

Cheers
Terry

I thought those were electric sheep? Anyhow, another thing to consider
is that it might be necessary to have non-volatile storage of some of
the information. Otherwise the operator could fool it by jogging the
power on and off-- operators are typically programmed to find any
possible weakness in your design and exploit it.


Best regards,
Spehro Pefhany

 

[Frank Bemelman]

I thought those were electric sheep? Anyhow, another thing to consider
is that it might be necessary to have non-volatile storage of some of
the information. Otherwise the operator could fool it by jogging the
power on and off-- operators are typically programmed to find any
possible weakness in your design and exploit it.

Oops, you want a powerswitch. That will be $300 extra.

 

[Spehro Pefhany]

Oops, you want a powerswitch. That will be $300 extra.

Even if you leave that out, the sneaky b*ggers have opposable thumbs
and enough intelligence (or perhaps some kind of instinct) to operate
the plug on the power cord.


Best regards,
Spehro Pefhany

 

[Tony Williams]

I thought those were electric sheep? Anyhow, another thing to
consider is that it might be necessary to have non-volatile
storage of some of the information. Otherwise the operator could
fool it by jogging the power on and off-- operators are typically
programmed to find any possible weakness in your design and
exploit it.

Aren't they just.

We could always do a belt and braces analogue of
the temperature rise in the solenoid, complete
with 'memory' and an emulation of heat loss.

NC
24V---+----+--------+-----+-----+-----+----o/o--->
| | | | | __|__ | Sol+
[R1] [R2] | [R3] _|_ | | |
| | | | D2/_\ |Relay|--+
_|_ | | | | |_____|
D1 \_/ | | _|_ | |
| |/e | D3\_/ +-----+ R1= 6k2
+--|pnp | | D4 | R2= 6k2
| |\ | +--+---|>|--+ R3= 12k
| | |/ | | R4= 47k
| | +--|npn | 24v | R5= 18k
| | | |\e +-|+\| | R6= 20K
| | | | | |Co>---+ R7= 10k
| | | +----+-----|-/| |
| | | | | | |
| +---|--|>|----|---|----|---+
| _|_ | D5 | | | |
| D5\_/ | | | | |
| | | [R4] | | |
| +---+---+ | | | o Sw1
| | | | | | / NC
[R5] [R6] |+ | [R7] | o
| /20k ===C1 | | | |
| \ 20|000u | | | |
| | | | | | |
0v----+----+-------+-----+---+----+---+->Solenoid-ve

When Sw1 is Opened, the relay is de-energised and
applies 24V to the solenoid. D5 lifts the short off
the 1mA c-c source, so C1 starts charging.

Roughly 300 secs later the voltage on C1 reaches
10.6V and the comparator output swings -ve, which
energises the relay. Solenoid is de-energised.

D5 shuts off the 1mA charging current and D3 pulls
the +ve input of the comparator down to 0.7V.

The solenoid remains Off until the R3 has reduced
the voltage on C1 down to below that 0.7V.

 

[Tony Williams]

On 04 Apr, [email protected] wrote:

Oh buggerit! Shouldn't do late editing....

Typos corrected below. There's probably more.

| +---|--|>|----|---|----|---+
| _|_ | D5 | | | |
| D6\_/ | | | | | ~~

The solenoid remains Off until the R6 has reduced

~~

 

[Frank Bemelman]

Aren't they just.

We could always do a belt and braces analogue of
the temperature rise in the solenoid, complete
with 'memory' and an emulation of heat loss.

[snip]

Perhaps you could use an NTC on a nice heatsink,
instead of a cap. Puts the environmental temperature
into the emulation... A piece of aluminium with plenty
holes in it, and a large bag of nuts and bolts, to
calibrate the heatsink