Driver to drive?

On Monday, December 15, 2014 11:56:00 PM UTC-5, Toyin wrote:
> I need a consultant to help me with my project for a fee. I would like to use a 555 timer circuit to generate a variable 1 to 5 minute timer to alternate between 2 bank of batteries that are connected to a charger and a load. There are four switches where two are on when the other two are off. Please send me a private email to <olutoyin at yahoo dot com> if you are interested and can help. Thanks!

Ummmm...if you have the power for a charger then you have power for the load, no batteries, timers or switches necessary.

You may send US$500 to:

Fred Bloggs
XX XXXX XX
XXXX, XXXX
USA

 

[George Herold]

On Monday, December 15, 2014 11:56:00 PM UTC-5, Toyin wrote:
> I need a consultant to help me with my project for a fee. I would like to use a 555 timer circuit to generate a variable 1 to 5 minute timer to alternate between 2 bank of batteries that are connected to a charger and a load. There are four switches where two are on when the other two are off. Please send me a private email to <olutoyin at yahoo dot com> if you are interested and can help. Thanks!

Are you toyin' with us? :^)

I can still remember the first 555 time circuit I made for myself.
I knew next to nothing and made a very drifty clock.
As long as you don't need too much accuracy the 555 or 4060 should be fine.

George H.

 

[David Eather]

On Wed, 17 Dec 2014 13:57:28 +1000, Toyin <olutoyin@yahoo.com> wrote:

On Monday, December 15, 2014 11:56:00 PM UTC-5, Toyin wrote:
I need a consultant to help me with my project for a fee. I would like
to use a 555 timer circuit to generate a variable 1 to 5 minute timer
to alternate between 2 bank of batteries that are connected to a
charger and a load. There are four switches where two are on when the
other two are off. Please send me a private email to <olutoyin at yahoo
dot com> if you are interested and can help. Thanks!

I just want to thank everyone for your invaluable input. Since this is
way over my head, I still need help and would contact some of the folks
who had replied and shared their contact information. Thanks again, I
do appreciate the suggestions.

-Toyin

look at

www.picaxe.co.uk

cheap, easiest to use and will do the job

 

[Joe Gwinn]

In article <m6r5c9$dtg$1@speranza.aioe.org>, Don Y <this@is.not.me.com>
wrote:

Hi,

A group for which I'd built a small "computer lab" dropped me
a note, today, indicating that they have a donor (business)
willing to supply them with "newer" (but still not "current")
machines (these are desktops).

Apparently, they have been offered several different make/models
(end of year "donate stuff to charity and write it off!").
Other than physical size and appearance, they are clueless as to
how to make this decision.

*I*, OTOH, am just SLIGHTLY less clueless (I know more about
screwdrivers than PC's!)

Things like amount of RAM *installed* aren't issues (I can freely get
whatever RAM I need). Ditto size of disk drive, optical media, etc.
(I'm not so sure about the video cards, though...)

This leaves clock frequency and number of cores as the big issues.
But, Intel (and AMD) have polluted the CPU namespace with so many
different models -- Pentium D, M, Core Duo, Xeon, Athlon, Megatron,
etc. -- that I suspect even those numbers are apples and oranges.

Anyone care to venture a *brief* description of the relative strengths
of this alphabet soup? And, a rough guide as to how to *try* to
relate specs from one "family" to another? E.g., if all you're doing
is browsing the web, MHz may be a good indicator. OTOH, if you're
watching *videos* (without GPU accelerator), then ....? Doing CAD
work would favor...? etc.

Sorry, I realize this is probably one of those questions to which a
firm answer is probably wishful thinking. It would, however, also
benefit *me* to get a better understanding of the markets addressed
by each of these.

[Note: donated kit is usually AT LEAST a couple of years old. I will
have to see if I can get more refined information -- but, knowing *which*
machines are of interest will help limit the information requested
(Nobody wants to have to prepare a list of *everything* that they might
be willing to "part with" -- don't annoy the donors! :> )]

As a practical matter, look first to which processors have good support
for programming and debugging of hardware and software, using widely
available tools of low cost, ones that won't soon disappear. The
existence of a large community is also helpful, as one can get
questions answered.

If one cannot program and debug, the processor speed isn't going to
matter.

Joe Gwinn

 

[MK]

On 17/12/2014 07:19, mike wrote:

On 12/16/2014 7:57 PM, Toyin wrote:
On Monday, December 15, 2014 11:56:00 PM UTC-5, Toyin wrote:
I need a consultant to help me with my project for a fee. I would
like to use a 555 timer circuit to generate a variable 1 to 5 minute
timer to alternate between 2 bank of batteries that are connected to
a charger and a load. There are four switches where two are on when
the other two are off. Please send me a private email to <olutoyin at
yahoo dot com> if you are interested and can help. Thanks!

I just want to thank everyone for your invaluable input. Since this is
way over my head, I still need help and would contact some of the
folks who had replied and shared their contact information. Thanks
again, I do appreciate the suggestions.

-Toyin

Since nobody else acknowledged the elephant in the room, I'll take a stab.
Your objective isn't clearly stated...
If you're charging one battery while loading the other,
What happens at the switchover?
Break before make glitches the power off.
Make before break risks breaking something with high
current between the batteries.

It's likely that you'll have issues well beyond timing.
The microprocessor solution gives you the opportunity
to address them. And having A/D converters available lets
you monitor everything and possibly decide that time is
not the optimum switching criterion. Also lets you
log performance and shove data out a LED that that
you can read with a phone/PDA.

You're likely to be disappointed with any rational
approach to a 5-minute analog delay.

I'd back up a level in the system design and approach
the whole range of issues.

I'm curious to know exactly what problem the switchover
solves???

Just to add some numbers to that 555 v uP decision, LMC555CMN from
Farnell costs 0.29 each on a reel of 5k. You can buy an 8 pin Cortex M0
for 0.33 (3k price break)(and there will be cheaper processors if you
look around). The extras to make the 555 give reliable 5 minute delays
will cost a lot more than Ł0.04.

Michael Kellett

 

[rickman]

On 12/17/2014 12:46 AM, Don Y wrote:

Hi,

A group for which I'd built a small "computer lab" dropped me
a note, today, indicating that they have a donor (business)
willing to supply them with "newer" (but still not "current")
machines (these are desktops).

Apparently, they have been offered several different make/models
(end of year "donate stuff to charity and write it off!").
Other than physical size and appearance, they are clueless as to
how to make this decision.

*I*, OTOH, am just SLIGHTLY less clueless (I know more about
screwdrivers than PC's!)

Things like amount of RAM *installed* aren't issues (I can freely get
whatever RAM I need). Ditto size of disk drive, optical media, etc.
(I'm not so sure about the video cards, though...)

This leaves clock frequency and number of cores as the big issues.
But, Intel (and AMD) have polluted the CPU namespace with so many
different models -- Pentium D, M, Core Duo, Xeon, Athlon, Megatron,
etc. -- that I suspect even those numbers are apples and oranges.

Anyone care to venture a *brief* description of the relative strengths
of this alphabet soup? And, a rough guide as to how to *try* to
relate specs from one "family" to another? E.g., if all you're doing
is browsing the web, MHz may be a good indicator. OTOH, if you're
watching *videos* (without GPU accelerator), then ....? Doing CAD
work would favor...? etc.

Sorry, I realize this is probably one of those questions to which a
firm answer is probably wishful thinking. It would, however, also
benefit *me* to get a better understanding of the markets addressed
by each of these.

[Note: donated kit is usually AT LEAST a couple of years old. I will
have to see if I can get more refined information -- but, knowing *which*
machines are of interest will help limit the information requested
(Nobody wants to have to prepare a list of *everything* that they might
be willing to "part with" -- don't annoy the donors! :> )]

I've never bothered too much with the details of the processor.
Important features are cache size and memory bandwidth (version and
number of memory interfaces). Remember that even when running a given
single thread application, the OS is still running a number of threads
and will need significant CPU time that can detract from the performance
of the application. So multi-core processors (including hyperthreading)
can be useful.

If memory is not a problem, please max out each configuration. If you
run out of available RAM this will have the single biggest impact on
processing speed. Modern browsers can be real memory hogs. So the
maximum RAM configuration of a machine should be one of the main
selection criteria.

--

Rick

 

[Phil Hobbs]

On 12/17/2014 09:40 AM, MK wrote:

On 17/12/2014 07:19, mike wrote:
On 12/16/2014 7:57 PM, Toyin wrote:
On Monday, December 15, 2014 11:56:00 PM UTC-5, Toyin wrote:
I need a consultant to help me with my project for a fee. I would
like to use a 555 timer circuit to generate a variable 1 to 5 minute
timer to alternate between 2 bank of batteries that are connected to
a charger and a load. There are four switches where two are on when
the other two are off. Please send me a private email to <olutoyin at
yahoo dot com> if you are interested and can help. Thanks!

I just want to thank everyone for your invaluable input. Since this is
way over my head, I still need help and would contact some of the
folks who had replied and shared their contact information. Thanks
again, I do appreciate the suggestions.

-Toyin

Since nobody else acknowledged the elephant in the room, I'll take a
stab.
Your objective isn't clearly stated...
If you're charging one battery while loading the other,
What happens at the switchover?
Break before make glitches the power off.
Make before break risks breaking something with high
current between the batteries.

It's likely that you'll have issues well beyond timing.
The microprocessor solution gives you the opportunity
to address them. And having A/D converters available lets
you monitor everything and possibly decide that time is
not the optimum switching criterion. Also lets you
log performance and shove data out a LED that that
you can read with a phone/PDA.

You're likely to be disappointed with any rational
approach to a 5-minute analog delay.

I'd back up a level in the system design and approach
the whole range of issues.

I'm curious to know exactly what problem the switchover
solves???
Just to add some numbers to that 555 v uP decision, LMC555CMN from
Farnell costs 0.29 each on a reel of 5k. You can buy an 8 pin Cortex M0
for 0.33 (3k price break)(and there will be cheaper processors if you
look around). The extras to make the 555 give reliable 5 minute delays
will cost a lot more than Ł0.04.

Michael Kellett

Sure, but since the OP isn't comfortable building a 555 circuit, setting
up a development system, learning C or PIC asm, and getting it working
is probably more than a 4d job.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

 

[Lasse Langwadt Christense]

Den onsdag den 17. december 2014 19.07.54 UTC+1 skrev Phil Hobbs:

On 12/17/2014 09:40 AM, MK wrote:
On 17/12/2014 07:19, mike wrote:
On 12/16/2014 7:57 PM, Toyin wrote:
On Monday, December 15, 2014 11:56:00 PM UTC-5, Toyin wrote:
I need a consultant to help me with my project for a fee. I would
like to use a 555 timer circuit to generate a variable 1 to 5 minute
timer to alternate between 2 bank of batteries that are connected to
a charger and a load. There are four switches where two are on when
the other two are off. Please send me a private email to <olutoyin at
yahoo dot com> if you are interested and can help. Thanks!

I just want to thank everyone for your invaluable input. Since this is
way over my head, I still need help and would contact some of the
folks who had replied and shared their contact information. Thanks
again, I do appreciate the suggestions.

-Toyin

Since nobody else acknowledged the elephant in the room, I'll take a
stab.
Your objective isn't clearly stated...
If you're charging one battery while loading the other,
What happens at the switchover?
Break before make glitches the power off.
Make before break risks breaking something with high
current between the batteries.

It's likely that you'll have issues well beyond timing.
The microprocessor solution gives you the opportunity
to address them. And having A/D converters available lets
you monitor everything and possibly decide that time is
not the optimum switching criterion. Also lets you
log performance and shove data out a LED that that
you can read with a phone/PDA.

You're likely to be disappointed with any rational
approach to a 5-minute analog delay.

I'd back up a level in the system design and approach
the whole range of issues.

I'm curious to know exactly what problem the switchover
solves???
Just to add some numbers to that 555 v uP decision, LMC555CMN from
Farnell costs 0.29 each on a reel of 5k. You can buy an 8 pin Cortex M0
for 0.33 (3k price break)(and there will be cheaper processors if you
look around). The extras to make the 555 give reliable 5 minute delays
will cost a lot more than Ł0.04.

Michael Kellett

Sure, but since the OP isn't comfortable building a 555 circuit, setting
up a development system, learning C or PIC asm, and getting it working
is probably more than a 4d job.

but he'll know how to do it next time

if lazy get something like this: http://www.ebay.co.uk/itm/121408732793

-Lasse

 

[John Larkin]

On Tue, 16 Dec 2014 16:52:52 -0800 (PST),
bloggs.fredbloggs.fred@gmail.com wrote:

On Tuesday, December 16, 2014 9:56:47 AM UTC-5, John Larkin wrote:
On Tue, 16 Dec 2014 04:43:43 -0800 (PST),
bloggs.fredbloggs.fred@gmail.com wrote:

On Monday, December 15, 2014 11:41:05 PM UTC-5, John Larkin wrote:
On Mon, 15 Dec 2014 19:04:03 -0800 (PST),
bloggs.fredbloggs.fred@gmail.com wrote:

On Monday, December 15, 2014 6:53:20 PM UTC-5, Jim Thompson wrote:


Mean to work inside that narrow a space.

Give me a break. Today I planted B&B clump amelanchier canadensis with ball dimensions of 24 x 24 x 18 inches of water saturated clay. At about 110 lbs per cubic foot (http://www.engineeringtoolbox.com/dirt-mud-densities-d_1727.html), this thing came in at between 500 and 600 Lbs, there is a slight taper to the cut so it's not a full 6 Ft^3. I had to hoist it about 250 ft to the planting location with an appliance dolly, dig a level hole to relatively precise dimensions, wrestle it into the hole, level it, flood it with 20 gals water, berm it, mulch it, admire it- about a two hour job- dunno why it always takes me so long.

Relative fun. I spent about 9 hours last weekend trying to fix the
leak in the living room ceiling. I've been battling this one for 15
years, and have got damned good at sheetrock repair.

Do you have any idea what the peak rainfall rate was? I heard the total there was only about 1.5", but, if it all comes down at once, it causes problems. A flat roof is anything less than 3 in 12 rise to run, they're non-trivial and require more than just slapping down a membrane.

I doubt that it ever hit 1" per hour. But our house looks down into a
wind tunnel called The Alamany Gap, so we get bursts of fat drops
going 50 MPH horizontally. That drives water into every nook and
cranny; sort of like having standing water on the *side* of the house.

Most roofs here are flat, with no visible pitch. I can walk most of
the block on peoples' roofs. The deck is basically a flat roof, too.
Tar and gravel construction.






There's a flat, roofed deck just above, with a sliding glass door. A
couple years ago, I had the whole deck re-roofed and a new sliding
door assembly installed. It still leaked.

1. Why are all contractors such jerks?

2. Why are all consumer products, regardless of price, such crap?

The roofing material should have gone UNDER the door frame. It didn't.

Well, it's not the roofing material but the "flashing" that's the problem. Grace is the de facto leader in state of the art flashing products.

https://grace.com/construction/en-us/Documents/TP-073J-V40.pdf

(surprisingly HomeDepot actually carries it...)

...is one example of their conformable, self-adhering, and easily installed product. Sounds like you need to lap it 4-6" minimum.


Too late now! I'd have to remove the entire sliding door thingie to
get under it.



People don't do carpentry any more, they use construction adhesive.
Makes things hard to work on. Trim boards come off with a chisel, one
wood sliver at a time.

The door frame is a bunch of insanely complex plastic extrusions,
designed to trap water in every possible place.

Among other things, I seriously hacked the door frame with a Dremel to
make channels to let the water out. A lot came out.

That doesn't sound right...Sounds like the door frame is too low on the roof deck. Tell the whiz you want an internal open gutter installed along the entire length of wall of the door, you'll need some kind of perforated metal grate covering the part where you step out the door. ( and this gutter needs slope -duh)

The frame is about 3" up, so it's not getting drowned. The projectile
water is hitting the glass, filling the channal below, and then
getting into the complex plastic structure.

So many things that I buy need to be redesigned. Consumer products are
such crap.

(I thought you'd enjoy a good bitchy world-gone-to-hell rant.)

Get a less complicated door and install it with "pan flashing."

http://www.buildingscience.com/documents/information-sheets/pan-flashing-for-exterior-wall-openings

The door you have now either defeats the pan flashing or the pan flashing was not installed or both.




--

John Larkin Highland Technology, Inc
picosecond timing laser drivers and controllers

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

I just ordered a 10m length USB borescope camera, $20 from Amazon.
Next time it rains, I'll drill a bunch of holes in the ceiling and
scope the top of the sheetrock, to see where the water is coming from.
Small holes are easy to patch.

The borescope should be handy for other things, like scoping pipes or
seeing what things have fallen into the crack behind my workbench.

The one I bought looks like a generic camera to Win XP, but needs
software installed for Win7. Why did Microsoft break the generic USB
camera interface?



--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[Toyin]

On Wednesday, December 17, 2014 2:20:13 AM UTC-5, mike wrote:

On 12/16/2014 7:57 PM, Toyin wrote:
On Monday, December 15, 2014 11:56:00 PM UTC-5, Toyin wrote:
I need a consultant to help me with my project for a fee. I would like to use a 555 timer circuit to generate a variable 1 to 5 minute timer to alternate between 2 bank of batteries that are connected to a charger and a load. There are four switches where two are on when the other two are off. Please send me a private email to <olutoyin at yahoo dot com> if you are interested and can help. Thanks!

I just want to thank everyone for your invaluable input. Since this is way over my head, I still need help and would contact some of the folks who had replied and shared their contact information. Thanks again, I do appreciate the suggestions.

-Toyin

Since nobody else acknowledged the elephant in the room, I'll take a stab..
Your objective isn't clearly stated...
If you're charging one battery while loading the other,
What happens at the switchover?
Break before make glitches the power off.
Make before break risks breaking something with high
current between the batteries.

It's likely that you'll have issues well beyond timing.
The microprocessor solution gives you the opportunity
to address them. And having A/D converters available lets
you monitor everything and possibly decide that time is
not the optimum switching criterion. Also lets you
log performance and shove data out a LED that that
you can read with a phone/PDA.

You're likely to be disappointed with any rational
approach to a 5-minute analog delay.

I'd back up a level in the system design and approach
the whole range of issues.

I'm curious to know exactly what problem the switchover
solves???

Hi Mike:
I wanted to power loads without the loads seeing the battery. So, the batteries will be connected to a charger as well as a super capacitor of equal voltage. So, the switch is to allow one battery to work while the other is on charge. I've been told this is not possible but I know wherever there's a will, there's always a way. Thanks for your insight. I truly appreciate it.

 

[Toyin]

On Wednesday, December 17, 2014 10:51:07 AM UTC-5, bloggs.fred...@gmail.com wrote:

On Monday, December 15, 2014 11:56:00 PM UTC-5, Toyin wrote:
I need a consultant to help me with my project for a fee. I would like to use a 555 timer circuit to generate a variable 1 to 5 minute timer to alternate between 2 bank of batteries that are connected to a charger and a load. There are four switches where two are on when the other two are off. Please send me a private email to <olutoyin at yahoo dot com> if you are interested and can help. Thanks!

Ummmm...if you have the power for a charger then you have power for the load, no batteries, timers or switches necessary.

You may send US$500 to:

Fred Bloggs
XX XXXX XX
XXXX, XXXX
USA

Hi:
Agree, but the charger can dump the same amp to one or more batteries at no increase in input. So, the reason for using battery bank.

 

On Wednesday, December 17, 2014 9:05:30 PM UTC-5, Toyin wrote:

On Wednesday, December 17, 2014 10:51:07 AM UTC-5, bloggs.fred...@gmail.com wrote:
On Monday, December 15, 2014 11:56:00 PM UTC-5, Toyin wrote:
I need a consultant to help me with my project for a fee. I would like to use a 555 timer circuit to generate a variable 1 to 5 minute timer to alternate between 2 bank of batteries that are connected to a charger and a load. There are four switches where two are on when the other two are off.. Please send me a private email to <olutoyin at yahoo dot com> if you are interested and can help. Thanks!

Ummmm...if you have the power for a charger then you have power for the load, no batteries, timers or switches necessary.

You may send US$500 to:

Fred Bloggs
XX XXXX XX
XXXX, XXXX
USA

Hi:
Agree, but the charger can dump the same amp to one or more batteries at no increase in input. So, the reason for using battery bank.

Do you understand that batteries do not store all the charge supplied to them by the charger? What this means is for certain battery technologies and high charging currents, the charger would have to supply up to twice the charge to the batteries than the batteries supply to the load. That would be called an extremely inefficient system, wasteful of energy, parts, space, and money, all unnecessarily.

 

[Phil Allison]

mike wrote:

My point, based on 40 years of watching very smart engineers
bang their heads against the wall trying to use devices unsuited for the
job,
is that reexamining the system architecture is likely to be more
fruitful than trying to design around all the subtle gotchas
required to get a reliable 5-minutes out of a 555.

** Back in 1977, I made myself a darkroom timer for B&W printing from negatives in an enlarger. It was based on a NE555 monostable.

A rotary switch selected resistors wired in 1:1.4 sequence, equating to stops on a camera. Another switch multiplied time settings by 10. The range was from 1 second to 450 seconds. 4x15uF tantalums provided the delay and the x10 times switch operated by pulling the voltage on pin 5 up and down for long and short delays respectively.

The OP could use switched resistors with a maximum of say 5Mohms for time setting and a 20uF worth of film cap for delay. Then pull pin 5 towards the supply with a trim pot and resistor in series of about 1kohms each to get exactly 300 seconds - which also calibrates the unit.

5% accuracy and repeatability should be easily had.


..... Phil

 

[mike]

On 12/17/2014 10:07 AM, Phil Hobbs wrote:

On 12/17/2014 09:40 AM, MK wrote:
On 17/12/2014 07:19, mike wrote:
On 12/16/2014 7:57 PM, Toyin wrote:
On Monday, December 15, 2014 11:56:00 PM UTC-5, Toyin wrote:
I need a consultant to help me with my project for a fee. I would
like to use a 555 timer circuit to generate a variable 1 to 5 minute
timer to alternate between 2 bank of batteries that are connected to
a charger and a load. There are four switches where two are on when
the other two are off. Please send me a private email to <olutoyin at
yahoo dot com> if you are interested and can help. Thanks!

I just want to thank everyone for your invaluable input. Since this is
way over my head, I still need help and would contact some of the
folks who had replied and shared their contact information. Thanks
again, I do appreciate the suggestions.

-Toyin

Since nobody else acknowledged the elephant in the room, I'll take a
stab.
Your objective isn't clearly stated...
If you're charging one battery while loading the other,
What happens at the switchover?
Break before make glitches the power off.
Make before break risks breaking something with high
current between the batteries.

It's likely that you'll have issues well beyond timing.
The microprocessor solution gives you the opportunity
to address them. And having A/D converters available lets
you monitor everything and possibly decide that time is
not the optimum switching criterion. Also lets you
log performance and shove data out a LED that that
you can read with a phone/PDA.

You're likely to be disappointed with any rational
approach to a 5-minute analog delay.

I'd back up a level in the system design and approach
the whole range of issues.

I'm curious to know exactly what problem the switchover
solves???
Just to add some numbers to that 555 v uP decision, LMC555CMN from
Farnell costs 0.29 each on a reel of 5k. You can buy an 8 pin Cortex M0
for 0.33 (3k price break)(and there will be cheaper processors if you
look around). The extras to make the 555 give reliable 5 minute delays
will cost a lot more than Ł0.04.

Michael Kellett

Sure, but since the OP isn't comfortable building a 555 circuit, setting
up a development system, learning C or PIC asm, and getting it working
is probably more than a 4d job.

Cheers

Phil Hobbs

Given the lack of info on the objectives and quantities,
it's difficult to speculate.

My point, based on 40 years of watching very smart engineers
bang their heads against the wall trying to use devices unsuited for the
job,
is that reexamining the system architecture is likely to be more
fruitful than trying to design around all the subtle gotchas
required to get a reliable 5-minutes out of a 555.

I'm all for using tools and devices matched to the designer's
skills and experience. I suggest that it's far easier to
learn a very valuable programming skill that, in this case,
requires little more than copying an example program,
than to learn all about current leakage on a circuit board
under reasonable environmental stresses.

If you don't have the skill for either task, might as well
learn the skill for the one likely to work.

 

[Bill Sloman]

On Thursday, 18 December 2014 14:40:02 UTC+11, Phil Allison wrote:

mike wrote:

My point, based on 40 years of watching very smart engineers
bang their heads against the wall trying to use devices unsuited for the
job,
is that reexamining the system architecture is likely to be more
fruitful than trying to design around all the subtle gotchas
required to get a reliable 5-minutes out of a 555.

** Back in 1977, I made myself a darkroom timer for B&W printing from negatives in an enlarger. It was based on a NE555 monostable.

A rotary switch selected resistors wired in 1:1.4 sequence, equating to stops on a camera. Another switch multiplied time settings by 10. The range was from 1 second to 450 seconds. 4x15uF tantalums provided the delay and the x10 times switch operated by pulling the voltage on pin 5 up and down for long and short delays respectively.

The OP could use switched resistors with a maximum of say 5Mohms for time setting and a 20uF worth of film cap for delay. Then pull pin 5 towards the supply with a trim pot and resistor in series of about 1kohms each to get exactly 300 seconds - which also calibrates the unit.

5% accuracy and repeatability should be easily had.

Not all that adventurous for 1977. CMOS had become relatively cheap by then, so a CD4060 and a 32768 Hz watch crystal could have given you a much more accurate time base. The nice thing about CMOS was that it offered quite wide counters in a single cheap package - 12-bits in the CD4040, and two decimal decades in the MC1458.

Setting up the numbers was a pain. Thumb-wheel switches were big, expensive and hard to mount. Screw-driver set-able PCB-mounting miniature rotary switches took a few more years to show up, as did single-chip microprocessors.

--
Bill Sloman, Sydney

 

[Phil Hobbs]

On 12/17/2014 6:12 PM, mike wrote:

On 12/17/2014 10:07 AM, Phil Hobbs wrote:
On 12/17/2014 09:40 AM, MK wrote:
On 17/12/2014 07:19, mike wrote:
On 12/16/2014 7:57 PM, Toyin wrote:
On Monday, December 15, 2014 11:56:00 PM UTC-5, Toyin wrote:
I need a consultant to help me with my project for a fee. I would
like to use a 555 timer circuit to generate a variable 1 to 5 minute
timer to alternate between 2 bank of batteries that are connected to
a charger and a load. There are four switches where two are on when
the other two are off. Please send me a private email to <olutoyin at
yahoo dot com> if you are interested and can help. Thanks!

I just want to thank everyone for your invaluable input. Since this is
way over my head, I still need help and would contact some of the
folks who had replied and shared their contact information. Thanks
again, I do appreciate the suggestions.

-Toyin

Since nobody else acknowledged the elephant in the room, I'll take a
stab.
Your objective isn't clearly stated...
If you're charging one battery while loading the other,
What happens at the switchover?
Break before make glitches the power off.
Make before break risks breaking something with high
current between the batteries.

It's likely that you'll have issues well beyond timing.
The microprocessor solution gives you the opportunity
to address them. And having A/D converters available lets
you monitor everything and possibly decide that time is
not the optimum switching criterion. Also lets you
log performance and shove data out a LED that that
you can read with a phone/PDA.

You're likely to be disappointed with any rational
approach to a 5-minute analog delay.

I'd back up a level in the system design and approach
the whole range of issues.

I'm curious to know exactly what problem the switchover
solves???
Just to add some numbers to that 555 v uP decision, LMC555CMN from
Farnell costs 0.29 each on a reel of 5k. You can buy an 8 pin Cortex M0
for 0.33 (3k price break)(and there will be cheaper processors if you
look around). The extras to make the 555 give reliable 5 minute delays
will cost a lot more than Ł0.04.

Michael Kellett

Sure, but since the OP isn't comfortable building a 555 circuit, setting
up a development system, learning C or PIC asm, and getting it working
is probably more than a 4d job.

Cheers

Phil Hobbs

Given the lack of info on the objectives and quantities,
it's difficult to speculate.

My point, based on 40 years of watching very smart engineers
bang their heads against the wall trying to use devices unsuited for the
job,
is that reexamining the system architecture is likely to be more
fruitful than trying to design around all the subtle gotchas
required to get a reliable 5-minutes out of a 555.

BITD when you had to use wet electros for the job, I agree. I suspect
that a polymer aluminum might do fine with a CMOS 555, inelegant as that is.

1meg * 330 uF makes a TC of 5.5 minutes. Connecting the cap from the
trigger input to VDD makes the leakage shorten the delay rather than
lengthening it (perhaps indefinitely).

Cheers

Phil Hobbs

I'm all for using tools and devices matched to the designer's
skills and experience. I suggest that it's far easier to
learn a very valuable programming skill that, in this case,
requires little more than copying an example program,
than to learn all about current leakage on a circuit board
under reasonable environmental stresses.

If you don't have the skill for either task, might as well
learn the skill for the one likely to work.

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

 

[mike]

On 12/17/2014 3:44 PM, Phil Hobbs wrote:

On 12/17/2014 6:12 PM, mike wrote:
On 12/17/2014 10:07 AM, Phil Hobbs wrote:
On 12/17/2014 09:40 AM, MK wrote:
On 17/12/2014 07:19, mike wrote:
On 12/16/2014 7:57 PM, Toyin wrote:
On Monday, December 15, 2014 11:56:00 PM UTC-5, Toyin wrote:
I need a consultant to help me with my project for a fee. I would
like to use a 555 timer circuit to generate a variable 1 to 5 minute
timer to alternate between 2 bank of batteries that are connected to
a charger and a load. There are four switches where two are on when
the other two are off. Please send me a private email to
olutoyin at
yahoo dot com> if you are interested and can help. Thanks!

I just want to thank everyone for your invaluable input. Since
this is
way over my head, I still need help and would contact some of the
folks who had replied and shared their contact information. Thanks
again, I do appreciate the suggestions.

-Toyin

Since nobody else acknowledged the elephant in the room, I'll take a
stab.
Your objective isn't clearly stated...
If you're charging one battery while loading the other,
What happens at the switchover?
Break before make glitches the power off.
Make before break risks breaking something with high
current between the batteries.

It's likely that you'll have issues well beyond timing.
The microprocessor solution gives you the opportunity
to address them. And having A/D converters available lets
you monitor everything and possibly decide that time is
not the optimum switching criterion. Also lets you
log performance and shove data out a LED that that
you can read with a phone/PDA.

You're likely to be disappointed with any rational
approach to a 5-minute analog delay.

I'd back up a level in the system design and approach
the whole range of issues.

I'm curious to know exactly what problem the switchover
solves???
Just to add some numbers to that 555 v uP decision, LMC555CMN from
Farnell costs 0.29 each on a reel of 5k. You can buy an 8 pin Cortex M0
for 0.33 (3k price break)(and there will be cheaper processors if you
look around). The extras to make the 555 give reliable 5 minute delays
will cost a lot more than Ł0.04.

Michael Kellett

Sure, but since the OP isn't comfortable building a 555 circuit, setting
up a development system, learning C or PIC asm, and getting it working
is probably more than a 4d job.

Cheers

Phil Hobbs

Given the lack of info on the objectives and quantities,
it's difficult to speculate.

My point, based on 40 years of watching very smart engineers
bang their heads against the wall trying to use devices unsuited for the
job,
is that reexamining the system architecture is likely to be more
fruitful than trying to design around all the subtle gotchas
required to get a reliable 5-minutes out of a 555.

BITD when you had to use wet electros for the job, I agree. I suspect
that a polymer aluminum might do fine with a CMOS 555, inelegant as that
is.

1meg * 330 uF makes a TC of 5.5 minutes. Connecting the cap from the
trigger input to VDD makes the leakage shorten the delay rather than
lengthening it (perhaps indefinitely).

Well, assuming that half of 5.5 minutes is tolerable, this time,
with this humidity at this temperature. And that's only one source
of leakage.

What's the cost of a 330 uF 5V polymer aluminum cap these
days?

A 555 is ill-suited even if you do have the skills
and budget to prevent catastrophic failure.

Cheers

Phil Hobbs


I'm all for using tools and devices matched to the designer's
skills and experience. I suggest that it's far easier to
learn a very valuable programming skill that, in this case,
requires little more than copying an example program,
than to learn all about current leakage on a circuit board
under reasonable environmental stresses.

If you don't have the skill for either task, might as well
learn the skill for the one likely to work.

 

[Tom Miller]

"mike" <ham789@netzero.net> wrote in message
news:m6t7a0$s9m$1@dont-email.me...

On 12/17/2014 3:44 PM, Phil Hobbs wrote:
On 12/17/2014 6:12 PM, mike wrote:
On 12/17/2014 10:07 AM, Phil Hobbs wrote:
On 12/17/2014 09:40 AM, MK wrote:
On 17/12/2014 07:19, mike wrote:
On 12/16/2014 7:57 PM, Toyin wrote:
On Monday, December 15, 2014 11:56:00 PM UTC-5, Toyin wrote:
I need a consultant to help me with my project for a fee. I would
like to use a 555 timer circuit to generate a variable 1 to 5
minute
timer to alternate between 2 bank of batteries that are connected
to
a charger and a load. There are four switches where two are on
when
the other two are off. Please send me a private email to
olutoyin at
yahoo dot com> if you are interested and can help. Thanks!

I just want to thank everyone for your invaluable input. Since
this is
way over my head, I still need help and would contact some of the
folks who had replied and shared their contact information. Thanks
again, I do appreciate the suggestions.

-Toyin

Since nobody else acknowledged the elephant in the room, I'll take a
stab.
Your objective isn't clearly stated...
If you're charging one battery while loading the other,
What happens at the switchover?
Break before make glitches the power off.
Make before break risks breaking something with high
current between the batteries.


Snipage
I'm curious to know exactly what problem the switchover
solves???
Just to add some numbers to that 555 v uP decision, LMC555CMN from
Farnell costs 0.29 each on a reel of 5k. You can buy an 8 pin Cortex
M0
for 0.33 (3k price break)(and there will be cheaper processors if you
look around). The extras to make the 555 give reliable 5 minute delays
will cost a lot more than Ł0.04.

Michael Kellett

Sure, but since the OP isn't comfortable building a 555 circuit,
setting
up a development system, learning C or PIC asm, and getting it working
is probably more than a 4d job.

Cheers

Phil Hobbs

Given the lack of info on the objectives and quantities,
it's difficult to speculate.

My point, based on 40 years of watching very smart engineers
bang their heads against the wall trying to use devices unsuited for the
job,
is that reexamining the system architecture is likely to be more
fruitful than trying to design around all the subtle gotchas
required to get a reliable 5-minutes out of a 555.

BITD when you had to use wet electros for the job, I agree. I suspect
that a polymer aluminum might do fine with a CMOS 555, inelegant as that
is.

1meg * 330 uF makes a TC of 5.5 minutes. Connecting the cap from the
trigger input to VDD makes the leakage shorten the delay rather than
lengthening it (perhaps indefinitely).

Well, assuming that half of 5.5 minutes is tolerable, this time,
with this humidity at this temperature. And that's only one source
of leakage.

What's the cost of a 330 uF 5V polymer aluminum cap these
days?

A 555 is ill-suited even if you do have the skills
and budget to prevent catastrophic failure.

Well, the ultimate Usenet solution would be a 555 clocking a PIC.

 

[mike]

On 12/17/2014 7:39 PM, Phil Allison wrote:

mike wrote:

My point, based on 40 years of watching very smart engineers
bang their heads against the wall trying to use devices unsuited for the
job,
is that reexamining the system architecture is likely to be more
fruitful than trying to design around all the subtle gotchas
required to get a reliable 5-minutes out of a 555.

** Back in 1977, I made myself a darkroom timer for B&W printing from negatives in an enlarger. It was based on a NE555 monostable.

A rotary switch selected resistors wired in 1:1.4 sequence, equating to stops on a camera. Another switch multiplied time settings by 10. The range was from 1 second to 450 seconds. 4x15uF tantalums provided the delay and the x10 times switch operated by pulling the voltage on pin 5 up and down for long and short delays respectively.

The OP could use switched resistors with a maximum of say 5Mohms for time setting and a 20uF worth of film cap for delay. Then pull pin 5 towards the supply with a trim pot and resistor in series of about 1kohms each to get exactly 300 seconds - which also calibrates the unit.

5% accuracy and repeatability should be easily had.


.... Phil

I'd agree that the 555 is one of the most versatile/useful devices in
history.
Emphasis on "history".
In 1977, that solution may have been far better than the alternatives.
Add up the parts cost today and compare that to a microcontroller solution.

I built a long-duration timer out of a pair of unijunction transistors.
But I wouldn't recommend it today.

Based on what little we know about the application, I judge that
there are a lot more issues involved in sequencing the transfer
that will require additional timing functions. Bite the bullet and
put in a microcontroller so you can fix stuff as you learn about those
problems.

I'd still recommend going back to the system architecture and taking
another look.

 

[mike]

On 12/17/2014 5:59 PM, Toyin wrote:

On Wednesday, December 17, 2014 2:20:13 AM UTC-5, mike wrote:
On 12/16/2014 7:57 PM, Toyin wrote:
On Monday, December 15, 2014 11:56:00 PM UTC-5, Toyin wrote:
I need a consultant to help me with my project for a fee. I would like to use a 555 timer circuit to generate a variable 1 to 5 minute timer to alternate between 2 bank of batteries that are connected to a charger and a load. There are four switches where two are on when the other two are off. Please send me a private email to <olutoyin at yahoo dot com> if you are interested and can help. Thanks!

I just want to thank everyone for your invaluable input. Since this is way over my head, I still need help and would contact some of the folks who had replied and shared their contact information. Thanks again, I do appreciate the suggestions.

-Toyin

Since nobody else acknowledged the elephant in the room, I'll take a stab.
Your objective isn't clearly stated...
If you're charging one battery while loading the other,
What happens at the switchover?
Break before make glitches the power off.
Make before break risks breaking something with high
current between the batteries.

It's likely that you'll have issues well beyond timing.
The microprocessor solution gives you the opportunity
to address them. And having A/D converters available lets
you monitor everything and possibly decide that time is
not the optimum switching criterion. Also lets you
log performance and shove data out a LED that that
you can read with a phone/PDA.

You're likely to be disappointed with any rational
approach to a 5-minute analog delay.

I'd back up a level in the system design and approach
the whole range of issues.

I'm curious to know exactly what problem the switchover
solves???

Hi Mike:
I wanted to power loads without the loads seeing the battery.

I'd like to understand exactly what that means. The purpose of the
battery is to supply current...What does "not seeing the battery mean?"
There's gotta be a reason to justify all this complexity???

How many volts and amps are we talking about here?
What's the battery technology?

So, the batteries will be connected to a charger as well as a

super capacitor of equal voltage.
New wrinkle. Connected how? Why?
If the voltages are equal, no current flows.
If the voltages are unequal and the impedance
is low, TOO MUCH current flows.
If the impedance is high, efficiency suffers.

So, the switch is to allow

one battery to work while the other is on charge.

What's the motivation? Why can't you just charge the battery
that's in use? If it's isolation, there may be much easier ways.

You asked for a 555 circuit and I'm lecturing you on system architecture.
I predict that you'll be putting patch on top of patch on top of
patch to kludge something into working.
I am trying to help you avoid doing that.

I've been told this is not possible but I know wherever there's a will,

there's always a way. Thanks for your insight. I truly appreciate it.
>