basic elapsed seconds counter

Guest
Hi,

I need to build a simple timer which simply counts elapsed time in
seconds as soon as current is turned on, then turns off and resets
when the power is disconnected. Or perhaps resets then begins counting
elapsed seconds, then shuts off when the power is disconnected. I
would like to display the seconds on an LCD or LED screen about the
size of a spoon.

I have no experience with electronics but I am keen to learn!
Hopefully this will be the start of many gadgets...

I really appreciate your help. Thanks!!!

-Ben
 
<ben.antonio@gsjbw.com> wrote in message
news:9c94df54-e8eb-4125-a70b-30ef66717ebe@s12g2000prg.googlegroups.com...
Hi,

I need to build a simple timer which simply counts elapsed time in
seconds as soon as current is turned on, then turns off and resets
when the power is disconnected. Or perhaps resets then begins counting
elapsed seconds, then shuts off when the power is disconnected. I
would like to display the seconds on an LCD or LED screen about the
size of a spoon.

I have no experience with electronics but I am keen to learn!
Hopefully this will be the start of many gadgets...

I really appreciate your help. Thanks!!!

-Ben
Click to expand...
What sort of accuracy do you need and how long will the timed period be?
(In other words, do you need "watch" accuracy, or within a couple of
percent, and how many digits will be needed to display the timed period?)

The timing is relatively easy, depending on accuracy and the length of
the timed period, but the display will take a bit more work.

For an LCD display, you would need a micro-controller, along with
programming skills, a compiler and a programmer and, of course, the other
hardware such as resistors, capacitors, diodes etc. Programmers and
compilers can cost a fair bit. Then you'd need to spend a bit of time
working up to the level you require. This method would provide the best
results, both in timing and quality of display, but is by far the most
expensive, especially if this is a small project.

LED displays are simpler, but need a few more chips for counting,
decoding and LED display segment driving, dependent on the number of digits.
One thing to consider is whether the unit will be used in relative darkness
or daylight. LEDs are best for darker settings and LCDs are more suited to
lighter environments.

A bit more info would help.
... Steve
 
On Feb 28, 3:28 pm, "Steve" <n...@thiswontwork.com> wrote:
ben.anto...@gsjbw.com> wrote in message

news:9c94df54-e8eb-4125-a70b-30ef66717ebe@s12g2000prg.googlegroups.com...

Hi,

I need to build a simple timer which simply counts elapsed time in
seconds as soon as current is turned on, then turns off and resets
when the power is disconnected. Or perhaps resets then begins counting
elapsed seconds, then shuts off when the power is disconnected. I
would like to display the seconds on an LCD or LED screen about the
size of a spoon.

I have no experience with electronics but I am keen to learn!
Hopefully this will be the start of many gadgets...

I really appreciate your help. Thanks!!!

-Ben

    What sort of accuracy do you need and how long will the timed period be?
(In other words, do you need "watch" accuracy, or within a couple of
percent, and how many digits will be needed to display the timed period?)

    The timing is relatively easy, depending on accuracy and the length of
the timed period, but the display will take a bit more work.

    For an LCD display, you would need a micro-controller, along with
programming skills, a compiler and a programmer and, of course, the other
hardware such as resistors, capacitors, diodes etc. Programmers and
compilers can cost a fair bit. Then you'd need to spend a bit of time
working up to the level you require. This method would provide the best
results, both in timing and quality of display, but is by far the most
expensive, especially if this is a small project.

    LED displays are simpler, but need a few more chips for counting,
decoding and LED display segment driving, dependent on the number of digits.
One thing to consider is whether the unit will be used in relative darkness
or daylight. LEDs are best for darker settings and LCDs are more suited to
lighter environments.

    A bit more info would help.
    ... Steve
Click to expand...
Thanks for the reply Steve,
A bit more info...
The accuracy is not an issue for me so long as it is 'fairly'
accurate. The only thing I can liken it to is when you step out a
distance- "right, that's 20 metres give or take a couple.". A maximum
time to count to would be 99 seconds. I have read a little about the
555 timer so I think that's my guy, but as for how I can use it for
this application, I'm stumped.

I also like the suggestion for a couple of segment LCD's to display
it. I hope this is enough info to get me started. Thanks again!
 
On Wed, 27 Feb 2008 23:07:53 -0800 (PST), ben.antonio@gsjbw.com wrote:

On Feb 28, 3:28 pm, "Steve" <n...@thiswontwork.com> wrote:
ben.anto...@gsjbw.com> wrote in message

news:9c94df54-e8eb-4125-a70b-30ef66717ebe@s12g2000prg.googlegroups.com...

Hi,

I need to build a simple timer which simply counts elapsed time in
seconds as soon as current is turned on, then turns off and resets
when the power is disconnected. Or perhaps resets then begins counting
elapsed seconds, then shuts off when the power is disconnected. I
would like to display the seconds on an LCD or LED screen about the
size of a spoon.

I have no experience with electronics but I am keen to learn!
Hopefully this will be the start of many gadgets...

I really appreciate your help. Thanks!!!

-Ben

    What sort of accuracy do you need and how long will the timed period be?
(In other words, do you need "watch" accuracy, or within a couple of
percent, and how many digits will be needed to display the timed period?)

    The timing is relatively easy, depending on accuracy and the length of
the timed period, but the display will take a bit more work.

    For an LCD display, you would need a micro-controller, along with
programming skills, a compiler and a programmer and, of course, the other
hardware such as resistors, capacitors, diodes etc. Programmers and
compilers can cost a fair bit. Then you'd need to spend a bit of time
working up to the level you require. This method would provide the best
results, both in timing and quality of display, but is by far the most
expensive, especially if this is a small project.

    LED displays are simpler, but need a few more chips for counting,
decoding and LED display segment driving, dependent on the number of digits.
One thing to consider is whether the unit will be used in relative darkness
or daylight. LEDs are best for darker settings and LCDs are more suited to
lighter environments.

    A bit more info would help.
    ... Steve

Thanks for the reply Steve,
A bit more info...
The accuracy is not an issue for me so long as it is 'fairly'
accurate. The only thing I can liken it to is when you step out a
distance- "right, that's 20 metres give or take a couple.". A maximum
time to count to would be 99 seconds. I have read a little about the
555 timer so I think that's my guy, but as for how I can use it for
this application, I'm stumped.

I also like the suggestion for a couple of segment LCD's to display
it. I hope this is enough info to get me started. Thanks again!
Click to expand...
I just had a wacko thought. Go to your nearest drugstore, Radio
Shack, or whatever, and pick up a cheap stopwatch built into a fairly
large case.

Build yourself a little "button pusher" -- maybe a reed relay circuit
-- driven when you want to start and stop the timing. Perform a
little microsurgery on the stopwatch to solder your button pusher
across the stopwatch's start/stop button.

Voila!

Tom
 
On Wed, 27 Feb 2008 23:07:53 -0800 (PST), ben.antonio@gsjbw.com
wrote:

On Feb 28, 3:28 pm, "Steve" <n...@thiswontwork.com> wrote:
ben.anto...@gsjbw.com> wrote in message

news:9c94df54-e8eb-4125-a70b-30ef66717ebe@s12g2000prg.googlegroups.com...

Hi,

I need to build a simple timer which simply counts elapsed time in
seconds as soon as current is turned on, then turns off and resets
when the power is disconnected. Or perhaps resets then begins counting
elapsed seconds, then shuts off when the power is disconnected. I
would like to display the seconds on an LCD or LED screen about the
size of a spoon.

I have no experience with electronics but I am keen to learn!
Hopefully this will be the start of many gadgets...

I really appreciate your help. Thanks!!!

-Ben

    What sort of accuracy do you need and how long will the timed period be?
(In other words, do you need "watch" accuracy, or within a couple of
percent, and how many digits will be needed to display the timed period?)

    The timing is relatively easy, depending on accuracy and the length of
the timed period, but the display will take a bit more work.

    For an LCD display, you would need a micro-controller, along with
programming skills, a compiler and a programmer and, of course, the other
hardware such as resistors, capacitors, diodes etc. Programmers and
compilers can cost a fair bit. Then you'd need to spend a bit of time
working up to the level you require. This method would provide the best
results, both in timing and quality of display, but is by far the most
expensive, especially if this is a small project.

    LED displays are simpler, but need a few more chips for counting,
decoding and LED display segment driving, dependent on the number of digits.
One thing to consider is whether the unit will be used in relative darkness
or daylight. LEDs are best for darker settings and LCDs are more suited to
lighter environments.

    A bit more info would help.
    ... Steve

Thanks for the reply Steve,
A bit more info...
The accuracy is not an issue for me so long as it is 'fairly'
accurate. The only thing I can liken it to is when you step out a
distance- "right, that's 20 metres give or take a couple.". A maximum
time to count to would be 99 seconds. I have read a little about the
555 timer so I think that's my guy, but as for how I can use it for
this application, I'm stumped.

I also like the suggestion for a couple of segment LCD's to display
it. I hope this is enough info to get me started. Thanks again!
Click to expand...
---
This will work: (View in Courier)


[7555]---[4510]---[4510]
| |
[7555]-+-[4543]---[4543]
| | |
+-[7SEG]---[7SEG]

Do you need a schematic?

--
JF
 
On Thu, 28 Feb 2008 00:47:50 -0800, Tom2000 <abuse@giganews.net>
wrote:

On Wed, 27 Feb 2008 23:07:53 -0800 (PST), ben.antonio@gsjbw.com wrote:

On Feb 28, 3:28 pm, "Steve" <n...@thiswontwork.com> wrote:
ben.anto...@gsjbw.com> wrote in message

news:9c94df54-e8eb-4125-a70b-30ef66717ebe@s12g2000prg.googlegroups.com...

Hi,

I need to build a simple timer which simply counts elapsed time in
seconds as soon as current is turned on, then turns off and resets
when the power is disconnected. Or perhaps resets then begins counting
elapsed seconds, then shuts off when the power is disconnected. I
would like to display the seconds on an LCD or LED screen about the
size of a spoon.

I have no experience with electronics but I am keen to learn!
Hopefully this will be the start of many gadgets...

I really appreciate your help. Thanks!!!

-Ben

    What sort of accuracy do you need and how long will the timed period be?
(In other words, do you need "watch" accuracy, or within a couple of
percent, and how many digits will be needed to display the timed period?)

    The timing is relatively easy, depending on accuracy and the length of
the timed period, but the display will take a bit more work.

    For an LCD display, you would need a micro-controller, along with
programming skills, a compiler and a programmer and, of course, the other
hardware such as resistors, capacitors, diodes etc. Programmers and
compilers can cost a fair bit. Then you'd need to spend a bit of time
working up to the level you require. This method would provide the best
results, both in timing and quality of display, but is by far the most
expensive, especially if this is a small project.

    LED displays are simpler, but need a few more chips for counting,
decoding and LED display segment driving, dependent on the number of digits.
One thing to consider is whether the unit will be used in relative darkness
or daylight. LEDs are best for darker settings and LCDs are more suited to
lighter environments.

    A bit more info would help.
    ... Steve

Thanks for the reply Steve,
A bit more info...
The accuracy is not an issue for me so long as it is 'fairly'
accurate. The only thing I can liken it to is when you step out a
distance- "right, that's 20 metres give or take a couple.". A maximum
time to count to would be 99 seconds. I have read a little about the
555 timer so I think that's my guy, but as for how I can use it for
this application, I'm stumped.

I also like the suggestion for a couple of segment LCD's to display
it. I hope this is enough info to get me started. Thanks again!

I just had a wacko thought. Go to your nearest drugstore, Radio
Shack, or whatever, and pick up a cheap stopwatch built into a fairly
large case.

Build yourself a little "button pusher" -- maybe a reed relay circuit
-- driven when you want to start and stop the timing. Perform a
little microsurgery on the stopwatch to solder your button pusher
across the stopwatch's start/stop button.

Voila!
Click to expand...
Or maybe one of those cheapo clocks (wristwatch or little giveaway
types) and see what happens if you disconnect and reconnect the
battery... if it starts countng seconds from 12:00:00 you are all set!


Back in the Olden Days when 4-function calculators first started
to become cheap, there were magazine articles on using them
for counters by faking a keypress. You might be able to use the
output of a 555 to provide the pulse, and just use the calculator
as the counter.

Best regards,


Bob Masta

DAQARTA v3.50
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, FREE Signal Generator
Science with your sound card!
 
On Feb 28, 10:59 pm, John Fields <jfie...@austininstruments.com>
wrote:
On Wed, 27 Feb 2008 23:07:53 -0800 (PST), ben.anto...@gsjbw.com
wrote:





On Feb 28, 3:28 pm, "Steve" <n...@thiswontwork.com> wrote:
ben.anto...@gsjbw.com> wrote in message

news:9c94df54-e8eb-4125-a70b-30ef66717ebe@s12g2000prg.googlegroups.com....

Hi,

I need to build a simple timer which simply counts elapsed time in
seconds as soon as current is turned on, then turns off and resets
when the power is disconnected. Or perhaps resets then begins counting
elapsed seconds, then shuts off when the power is disconnected. I
would like to display the seconds on an LCD or LED screen about the
size of a spoon.

I have no experience with electronics but I am keen to learn!
Hopefully this will be the start of many gadgets...

I really appreciate your help. Thanks!!!

-Ben

    What sort of accuracy do you need and how long will the timed period be?
(In other words, do you need "watch" accuracy, or within a couple of
percent, and how many digits will be needed to display the timed period?)

    The timing is relatively easy, depending on accuracy and the length of
the timed period, but the display will take a bit more work.

    For an LCD display, you would need a micro-controller, along with
programming skills, a compiler and a programmer and, of course, the other
hardware such as resistors, capacitors, diodes etc. Programmers and
compilers can cost a fair bit. Then you'd need to spend a bit of time
working up to the level you require. This method would provide the best
results, both in timing and quality of display, but is by far the most
expensive, especially if this is a small project.

    LED displays are simpler, but need a few more chips for counting,
decoding and LED display segment driving, dependent on the number of digits.
One thing to consider is whether the unit will be used in relative darkness
or daylight. LEDs are best for darker settings and LCDs are more suited to
lighter environments.

    A bit more info would help.
    ... Steve

Thanks for the reply Steve,
A bit more info...
The accuracy is not an issue for me so long as it is 'fairly'
accurate. The only thing I can liken it to is when you step out a
distance- "right, that's 20 metres give or take a couple.". A maximum
time to count to would be 99 seconds. I have read a little about the
555 timer so I think that's my guy, but as for how I can use it for
this application, I'm stumped.

I also like the suggestion for a couple of segment LCD's to display
it. I hope this is enough info to get me started. Thanks again!

---
This will work: (View in Courier)

   [7555]---[4510]---[4510]
              |        |
   [7555]-+-[4543]---[4543]        
          |   |        |
          +-[7SEG]---[7SEG]

Do you need a schematic?

--
JF- Hide quoted text -

- Show quoted text -
Click to expand...
Hi John,

Yes- a schematic would be great! Just looking into it now can you
correct my logic?
7555 (provides timed pulses)-----4510(converts pulses to binary
code)-----4543(converts binary code to drive 7 seg)-----7 seg(displays
4543 input).
A couple of questions:
-How can you set the 7555 to count seconds?
-How can this be reset before each count?
-How on earth can I build it????
Very keen to learn about this frontier! Thanks for the assistance
 
On Feb 27, 4:13 pm, ben.anto...@gsjbw.com wrote:
Hi,

I need to build a simple timer which simply counts elapsed time in
seconds as soon as current is turned on, then turns off and resets
when the power is disconnected. Or perhaps resets then begins counting
elapsed seconds, then shuts off when the power is disconnected. I
would like to display the seconds on an LCD or LED screen about the
size of a spoon.

I have no experience with electronics but I am keen to learn!
Hopefully this will be the start of many gadgets...

I really appreciate your help. Thanks!!!

-Ben
Click to expand...
The circuit given, with an oscillator, counters and 7-segment drivers,
is the most straightforward. However, FYI, I think most people today
would use a small microcontroller instead. That does not mean I'm
suggesting you try that approach now, given your lack of experience.
I'm simply planting a seed for consideration down the road, should you
find yourself becoming more interested in things electronic.

This approach would use a microcontroller (around $2) to do the job of
the oscillator, counters and drivers. You could also get fancy and
wire in some buttons, a flashing LED or two, etc etc.

Mike
 
On Feb 27, 3:13 pm, ben.anto...@gsjbw.com wrote:
Hi,

I need to build a simple timer which simply counts elapsed time in
seconds as soon as current is turned on, then turns off and resets
when the power is disconnected. Or perhaps resets then begins counting
elapsed seconds, then shuts off when the power is disconnected. I
would like to display the seconds on an LCD or LED screen about the
size of a spoon.

I have no experience with electronics but I am keen to learn!
Hopefully this will be the start of many gadgets...

I really appreciate your help. Thanks!!!

-Ben
Click to expand...
Depending on what else you might want to do, here's a device that I've
found handy for counting elapsed seconds with a minimum of muss &
fuss:

http://www.maxim-ic.com.cn/getds.cfm?qv_pk=2729

JM
 
On Feb 29, 11:26 am, Mike Silva <snarflem...@yahoo.com> wrote:
On Feb 27, 4:13 pm, ben.anto...@gsjbw.com wrote:

Hi,

I need to build a simple timer which simply counts elapsed time in
seconds as soon as current is turned on, then turns off and resets
when the power is disconnected. Or perhaps resets then begins counting
elapsed seconds, then shuts off when the power is disconnected. I
would like to display the seconds on an LCD or LED screen about the
size of a spoon.

I have no experience with electronics but I am keen to learn!
Hopefully this will be the start of many gadgets...

I really appreciate your help. Thanks!!!

-Ben

The circuit given, with an oscillator, counters and 7-segment drivers,
is the most straightforward.  However, FYI, I think most people today
would use a small microcontroller instead.  That does not mean I'm
suggesting you try that approach now, given your lack of experience.
I'm simply planting a seed for consideration down the road, should you
find yourself becoming more interested in things electronic.

This approach would use a microcontroller (around $2) to do the job of
the oscillator, counters and drivers.  You could also get fancy and
wire in some buttons, a flashing LED or two, etc etc.

Mike
Click to expand...
Thanks Mike. It appears a microcontroller combines all tasks into a
single unit, and $2 is plenty cheap enough. But what makes this method
more complex? Do I need computer programs etc to program it? Thanks
for the suggestion
 
On Feb 29, 12:21 pm, John Mianowski <spamf...@skytex.net> wrote:
On Feb 27, 3:13 pm, ben.anto...@gsjbw.com wrote:

Hi,

I need to build a simple timer which simply counts elapsed time in
seconds as soon as current is turned on, then turns off and resets
when the power is disconnected. Or perhaps resets then begins counting
elapsed seconds, then shuts off when the power is disconnected. I
would like to display the seconds on an LCD or LED screen about the
size of a spoon.

I have no experience with electronics but I am keen to learn!
Hopefully this will be the start of many gadgets...

I really appreciate your help. Thanks!!!

-Ben

Depending on what else you might want to do, here's a device that I've
found handy for counting elapsed seconds with a minimum of muss &
fuss:

http://www.maxim-ic.com.cn/getds.cfm?qv_pk=2729

JM
Click to expand...
Hi John,

Thanks for the link, I will check it out now. Simple and
straigthforward sounds appealing... I will post back with any
questions if that's ok. Cheers
 
On Feb 29, 12:21 pm, John Mianowski <spamf...@skytex.net> wrote:
On Feb 27, 3:13 pm, ben.anto...@gsjbw.com wrote:

Hi,

I need to build a simple timer which simply counts elapsed time in
seconds as soon as current is turned on, then turns off and resets
when the power is disconnected. Or perhaps resets then begins counting
elapsed seconds, then shuts off when the power is disconnected. I
would like to display the seconds on an LCD or LED screen about the
size of a spoon.

I have no experience with electronics but I am keen to learn!
Hopefully this will be the start of many gadgets...

I really appreciate your help. Thanks!!!

-Ben

Depending on what else you might want to do, here's a device that I've
found handy for counting elapsed seconds with a minimum of muss &
fuss:

http://www.maxim-ic.com.cn/getds.cfm?qv_pk=2729

JM
Click to expand...
I'm sorry John, but this module is too expensive. I would like to keep
the cost to <$5 complete. Plus the instruction is over my head. Thank
you for the help.
The purpose of this timer is to count the amount of penalty time for
our indoor soccer game (it's a board game). It would be great to flick
a switch and it counts up, flick it and it stops.
 
On Feb 28, 8:26 pm, ben.anto...@gsjbw.com wrote:

Thanks Mike. It appears a microcontroller combines all tasks into a
single unit, and $2 is plenty cheap enough. But what makes this method
more complex? Do I need computer programs etc to program it? Thanks
for the suggestion
Click to expand...
1) It requires knowing how to write software for the device.
2) It requires understanding the device hardware (timers, I/O ports,
etc).
3) It requires a toolset. This can just be a free assembler program
for your case.
4) It requires a way to download a program into the micro. This can
be a simple parallel-port programmer, or a USB-based device.

None of this is particularly complex, but it's certainly not as easy
as wiring up 5 small chips.

For the price of this added complexity you get corresponding benefits,
the biggest of which are the ability to add functionality without
adding much if any hardware, and to quickly and easily experiment and
modify the functionality, to tweak the design. It can also be a heck
of a lot of fun.

Mike
 
On Feb 29, 1:19 pm, Mike Silva <snarflem...@yahoo.com> wrote:
On Feb 28, 8:26 pm, ben.anto...@gsjbw.com wrote:

Thanks Mike. It appears a microcontroller combines all tasks into a
single unit, and $2 is plenty cheap enough. But what makes this method
more complex? Do I need computer programs etc to program it? Thanks
for the suggestion

1) It requires knowing how to write software for the device.
2) It requires understanding the device hardware (timers, I/O ports,
etc).
3) It requires a toolset.  This can just be a free assembler program
for your case.
4) It requires a way to download a program into the micro.  This can
be a simple parallel-port programmer, or a USB-based device.

None of this is particularly complex, but it's certainly not as easy
as wiring up 5 small chips.

For the price of this added complexity you get corresponding benefits,
the biggest of which are the ability to add functionality without
adding much if any hardware, and to quickly and easily experiment and
modify the functionality, to tweak the design.  It can also be a heck
of a lot of fun.

Mike
Click to expand...
Do you know of any resources which can help me learn about
microcontrollers? I am also still very interested in wiring up 5 small
chips however...
 
On Feb 28, 9:37 pm, ben.anto...@gsjbw.com wrote:
Do you know of any resources which can help me learn about
microcontrollers? I am also still very interested in wiring up 5 small
chips however...
Click to expand...
avrfreaks.net and 8052.com are two sites that come to mind. They have
forums, tutorials, etc.

Mike
 
On Thu, 28 Feb 2008 14:54:54 -0800 (PST), ben.antonio@gsjbw.com
wrote:

On Feb 28, 10:59 pm, John Fields <jfie...@austininstruments.com
wrote:
On Wed, 27 Feb 2008 23:07:53 -0800 (PST), ben.anto...@gsjbw.com
wrote:





On Feb 28, 3:28 pm, "Steve" <n...@thiswontwork.com> wrote:
ben.anto...@gsjbw.com> wrote in message

news:9c94df54-e8eb-4125-a70b-30ef66717ebe@s12g2000prg.googlegroups.com...

Hi,

I need to build a simple timer which simply counts elapsed time in
seconds as soon as current is turned on, then turns off and resets
when the power is disconnected. Or perhaps resets then begins counting
elapsed seconds, then shuts off when the power is disconnected. I
would like to display the seconds on an LCD or LED screen about the
size of a spoon.

I have no experience with electronics but I am keen to learn!
Hopefully this will be the start of many gadgets...

I really appreciate your help. Thanks!!!

-Ben

    What sort of accuracy do you need and how long will the timed period be?
(In other words, do you need "watch" accuracy, or within a couple of
percent, and how many digits will be needed to display the timed period?)

    The timing is relatively easy, depending on accuracy and the length of
the timed period, but the display will take a bit more work.

    For an LCD display, you would need a micro-controller, along with
programming skills, a compiler and a programmer and, of course, the other
hardware such as resistors, capacitors, diodes etc. Programmers and
compilers can cost a fair bit. Then you'd need to spend a bit of time
working up to the level you require. This method would provide the best
results, both in timing and quality of display, but is by far the most
expensive, especially if this is a small project.

    LED displays are simpler, but need a few more chips for counting,
decoding and LED display segment driving, dependent on the number of digits.
One thing to consider is whether the unit will be used in relative darkness
or daylight. LEDs are best for darker settings and LCDs are more suited to
lighter environments.

    A bit more info would help.
    ... Steve

Thanks for the reply Steve,
A bit more info...
The accuracy is not an issue for me so long as it is 'fairly'
accurate. The only thing I can liken it to is when you step out a
distance- "right, that's 20 metres give or take a couple.". A maximum
time to count to would be 99 seconds. I have read a little about the
555 timer so I think that's my guy, but as for how I can use it for
this application, I'm stumped.

I also like the suggestion for a couple of segment LCD's to display
it. I hope this is enough info to get me started. Thanks again!

---
This will work: (View in Courier)

   [7555]---[4510]---[4510]
              |        |
   [7555]-+-[4543]---[4543]        
          |   |        |
          +-[7SEG]---[7SEG]

Do you need a schematic?

--
JF- Hide quoted text -

- Show quoted text -

Hi John,

Yes- a schematic would be great! Just looking into it now can you
correct my logic?
7555 (provides timed pulses)-----4510(converts pulses to binary
code)-----4543(converts binary code to drive 7 seg)-----7 seg(displays
4543 input).
A couple of questions:
-How can you set the 7555 to count seconds?
Click to expand...
---
I've posted a schematic for you on
alt.binaries.schematics.electronic, and R5 is used to set the timer
clock frequency.
---

-How can this be reset before each count?
Click to expand...
---
I don't understand. Do you want to have, say, a pushbutton which,
when it's pressed and released will cause the count to go to zero
and then start counting up again?

If so, then probably the easiest way would be to rewire the 4510s'
RESETs like this: (View in Courier)


Vcc
| U2
| <--+ +----+
| | | |
O [C3] | |
| | | |
+----+---|R |
| +----+
|
| U5
| +----+
| | |
| | |
| | |
+---|R |
| +----+
|
[R3]
|
GND

then get rid of R1, C1, and C4, and connect the 7555's RESETS to
Vcc.
---

-How on earth can I build it????
Click to expand...
---
Probably the easiest way for you, since you're just starting out,
would be to use one of those plastic breadboard thingies you can
plug components and wires into to connect things up.

If you go to:

http://www.elenco.com/

and then click on "Electronics Division", then on "Breadboard and
Prototyping" and finally on any of the first ten entries in the
"Item" column you'll see what I mean.

For an example of how they're used, goto:

http://www.kpsec.freeuk.com/breadb.htm
---

Very keen to learn about this frontier! Thanks for the assistance
Click to expand...
---
My pleasure! :)

--
JF
 
On Mar 1, 3:02 am, John Fields <jfie...@austininstruments.com> wrote:
On Thu, 28 Feb 2008 14:54:54 -0800 (PST), ben.anto...@gsjbw.com
wrote:





On Feb 28, 10:59 pm, John Fields <jfie...@austininstruments.com
wrote:
On Wed, 27 Feb 2008 23:07:53 -0800 (PST), ben.anto...@gsjbw.com
wrote:

On Feb 28, 3:28 pm, "Steve" <n...@thiswontwork.com> wrote:
ben.anto...@gsjbw.com> wrote in message

news:9c94df54-e8eb-4125-a70b-30ef66717ebe@s12g2000prg.googlegroups.com...

Hi,

I need to build a simple timer which simply counts elapsed time in
seconds as soon as current is turned on, then turns off and resets
when the power is disconnected. Or perhaps resets then begins counting
elapsed seconds, then shuts off when the power is disconnected. I
would like to display the seconds on an LCD or LED screen about the
size of a spoon.

I have no experience with electronics but I am keen to learn!
Hopefully this will be the start of many gadgets...

I really appreciate your help. Thanks!!!

-Ben

    What sort of accuracy do you need and how long will the timed period be?
(In other words, do you need "watch" accuracy, or within a couple of
percent, and how many digits will be needed to display the timed period?)

    The timing is relatively easy, depending on accuracy and the length of
the timed period, but the display will take a bit more work.

    For an LCD display, you would need a micro-controller, along with
programming skills, a compiler and a programmer and, of course, the other
hardware such as resistors, capacitors, diodes etc. Programmers and
compilers can cost a fair bit. Then you'd need to spend a bit of time
working up to the level you require. This method would provide the best
results, both in timing and quality of display, but is by far the most
expensive, especially if this is a small project.

    LED displays are simpler, but need a few more chips for counting,
decoding and LED display segment driving, dependent on the number of digits.
One thing to consider is whether the unit will be used in relative darkness
or daylight. LEDs are best for darker settings and LCDs are more suited to
lighter environments.

    A bit more info would help.
    ... Steve

Thanks for the reply Steve,
A bit more info...
The accuracy is not an issue for me so long as it is 'fairly'
accurate. The only thing I can liken it to is when you step out a
distance- "right, that's 20 metres give or take a couple.". A maximum
time to count to would be 99 seconds. I have read a little about the
555 timer so I think that's my guy, but as for how I can use it for
this application, I'm stumped.

I also like the suggestion for a couple of segment LCD's to display
it. I hope this is enough info to get me started. Thanks again!

---
This will work: (View in Courier)

   [7555]---[4510]---[4510]
              |        |
   [7555]-+-[4543]---[4543]        
          |   |        |
          +-[7SEG]---[7SEG]

Do you need a schematic?

--
JF- Hide quoted text -

- Show quoted text -

Hi John,

Yes- a schematic would be great! Just looking into it now can you
correct my logic?
7555 (provides timed pulses)-----4510(converts pulses to binary
code)-----4543(converts binary code to drive 7 seg)-----7 seg(displays
4543 input).
A couple of questions:
-How can you set the 7555 to count seconds?

---
I've posted a schematic for you on
alt.binaries.schematics.electronic, and R5 is used to set the timer
clock frequency.
---

-How can this be reset before each count?

---
I don't understand.  Do you want to have, say, a pushbutton which,
when it's pressed and released will cause the count to go to zero
and then start counting up again?

If so, then probably the easiest way would be to rewire the 4510s'
RESETs like this: (View in Courier)

        Vcc
         |     U2
    | <--+   +----+    
    |    |   |    |
    O   [C3] |    |
    |    |   |    |
    +----+---|R   |
         |   +----+
         |
         |     U5
         |   +----+
         |   |    |
         |   |    |
         |   |    |
         +---|R   |
         |   +----+
         |
        [R3]
         |
        GND

then get rid of R1, C1, and C4, and connect the 7555's RESETS to
Vcc.
---

-How on earth can I build it????

---
Probably the easiest way for you, since you're just starting out,
would be to use one of those plastic breadboard thingies you can
plug components and wires into to connect things up.

If you go to:

http://www.elenco.com/

and then click on "Electronics Division", then on "Breadboard and
Prototyping" and finally on any of the first ten entries in the
"Item" column you'll see what I mean.

For an example of how they're used, goto:

http://www.kpsec.freeuk.com/breadb.htm
---

Very keen to learn about this frontier! Thanks for the assistance

---
My pleasure! :)

--
JF- Hide quoted text -

- Show quoted text -
Click to expand...
Hi John,

Thank you very much for your help. However I am unable to get your
schematic (I have been at it for 2 hours!). Is there another place
where I can access it? Perhaps email? Thanks again -Ben
 
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