My component level electronics is rusty, including RC circuit calculations, having been doing module swapping for years. This is probably a very simple question for the folks here....

Is this a reasonable circuit for a delay timer?

If so, how would I calculate the values of R &C for this...

1. Switch closes
2. After 5 seconds, the relay energizes and remains energized until switch is opened.

Sketch...
http://img839.imageshack.us/img839/4650/uh3.gif

Thanks in advance!

Bob

On 9/4/2013 3:40 PM, Guv Bob wrote:
My component level electronics is rusty, including RC circuit calculations, having been doing module swapping for years. This is probably a very simple question for the folks here....

Is this a reasonable circuit for a delay timer?

If so, how would I calculate the values of R &C for this...

1. Switch closes
2. After 5 seconds, the relay energizes and remains energized until switch is opened.

Sketch...
http://img839.imageshack.us/img839/4650/uh3.gif

Thanks in advance!

Bob


What is the minimum activation voltage of the relay coil? What is the
maximum coil voltage of the relay? What is the typical resistance of the
relay coil?

"Guv Bob" schreef in bericht
m...
My component level electronics is rusty, including RC circuit calculations,
having been doing module swapping for years. This is probably a very
simple question for the folks here....

Is this a reasonable circuit for a delay timer?

If so, how would I calculate the values of R &C for this...

1. Switch closes
2. After 5 seconds, the relay energizes and remains energized until switch
is opened.

Sketch...
http://img839.imageshack.us/img839/4650/uh3.gif

Thanks in advance!

Bob


Yo or nes. As so often it depends. You will have some delay from some us to
eternaly depending on R, C and the ratings of the relay. If the relay is
activated it may do so slowly and the timing will be inaccurate.

Be aware that the LED will need some current limiter.

petrus bitbyter

"RosemontCrest" wrote in message ...
On 9/4/2013 3:40 PM, Guv Bob wrote:
My component level electronics is rusty, including RC circuit calculations, having been doing module swapping for years. This is probably a very simple question for the folks here....

Is this a reasonable circuit for a delay timer?

If so, how would I calculate the values of R &C for this...

1. Switch closes
2. After 5 seconds, the relay energizes and remains energized until switch is opened.

Sketch...
http://img839.imageshack.us/img839/4650/uh3.gif

Thanks in advance!

Bob


What is the minimum activation voltage of the relay coil? What is the
maximum coil voltage of the relay? What is the typical resistance of the
relay coil?

I'm using the relay shown in this MK111 circuit...
http://www.vellemanusa.com/downloads...nual_mk111.pdf

"Guv Bob" wrote in message news "RosemontCrest" wrote in message ...
On 9/4/2013 3:40 PM, Guv Bob wrote:
My component level electronics is rusty, including RC circuit calculations, having been doing module swapping for years. This is probably a very simple question for the folks here....

Is this a reasonable circuit for a delay timer?

If so, how would I calculate the values of R &C for this...

1. Switch closes
2. After 5 seconds, the relay energizes and remains energized until switch is opened.

Sketch...
http://img839.imageshack.us/img839/4650/uh3.gif

Thanks in advance!

Bob


What is the minimum activation voltage of the relay coil? What is the
maximum coil voltage of the relay? What is the typical resistance of the
relay coil?

I'm using the relay shown in this MK111 circuit...
http://www.vellemanusa.com/downloads...nual_mk111.pdf

PS -- Photo of relay and data sheet attached.

On Thu, 05 Sep 2013 13:47:53 -0700, Guv Bob wrote:

"Guv Bob" wrote in message
news "RosemontCrest" wrote in message
...
On 9/4/2013 3:40 PM, Guv Bob wrote:
My component level electronics is rusty, including RC circuit
calculations, having been doing module swapping for years. This is
probably a very simple question for the folks here....

Is this a reasonable circuit for a delay timer?

If so, how would I calculate the values of R &C for this...

1. Switch closes 2. After 5 seconds, the relay energizes and
remains energized until switch is opened.

Sketch...
http://img839.imageshack.us/img839/4650/uh3.gif

Thanks in advance!

Bob


What is the minimum activation voltage of the relay coil? What is the
maximum coil voltage of the relay? What is the typical resistance of
the relay coil?

I'm using the relay shown in this MK111 circuit...
http://www.vellemanusa.com/downloads...nual_mk111.pdf

PS -- Photo of relay and data sheet attached.

Relay characteristics aren't controlled closely. As long as they meet
the guaranteed specs, that's all that counts. Anything better than that
is OK. This means that the circuit you propose can have a different
delay if you substitute another relay, even if it is the same type.

Therefore, you really can't calculate the values unless you measure the
characteristics of the particular relay you are going to use. It would
be easier to just try different values of the parts until you get the
result you want. As someones else pointed out, even then the results are
likely to be inconsistent.

This is the problem that 555 timer ICs solve. Consider using one.

--
Jim Mueller

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.

"Jim Mueller" wrote in message eb.com...
On Thu, 05 Sep 2013 13:47:53 -0700, Guv Bob wrote:

"Guv Bob" wrote in message
news "RosemontCrest" wrote in message
...
On 9/4/2013 3:40 PM, Guv Bob wrote:
My component level electronics is rusty, including RC circuit
calculations, having been doing module swapping for years. This is
probably a very simple question for the folks here....

Is this a reasonable circuit for a delay timer?

If so, how would I calculate the values of R &C for this...

1. Switch closes 2. After 5 seconds, the relay energizes and
remains energized until switch is opened.

Sketch...
http://img839.imageshack.us/img839/4650/uh3.gif

Thanks in advance!

Bob


What is the minimum activation voltage of the relay coil? What is the
maximum coil voltage of the relay? What is the typical resistance of
the relay coil?

I'm using the relay shown in this MK111 circuit...
http://www.vellemanusa.com/downloads...nual_mk111.pdf

PS -- Photo of relay and data sheet attached.

Relay characteristics aren't controlled closely. As long as they meet
the guaranteed specs, that's all that counts. Anything better than that
is OK. This means that the circuit you propose can have a different
delay if you substitute another relay, even if it is the same type.

Therefore, you really can't calculate the values unless you measure the
characteristics of the particular relay you are going to use. It would
be easier to just try different values of the parts until you get the
result you want. As someones else pointed out, even then the results are
likely to be inconsistent.

This is the problem that 555 timer ICs solve. Consider using one.

--
Jim Mueller

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.


Thanks Jim. I have no experience with 555 timers. Where would I find a basic circuit for this application using a 555?

On Fri, 6 Sep 2013 09:57:57 -0700, "Guv Bob"
wrote:

"Jim Mueller" wrote in message eb.com...
On Thu, 05 Sep 2013 13:47:53 -0700, Guv Bob wrote:

"Guv Bob" wrote in message
news "RosemontCrest" wrote in message
...
On 9/4/2013 3:40 PM, Guv Bob wrote:
My component level electronics is rusty, including RC circuit
calculations, having been doing module swapping for years. This is
probably a very simple question for the folks here....

Is this a reasonable circuit for a delay timer?

If so, how would I calculate the values of R &C for this...

1. Switch closes 2. After 5 seconds, the relay energizes and
remains energized until switch is opened.

Sketch...
http://img839.imageshack.us/img839/4650/uh3.gif

Thanks in advance!

Bob


What is the minimum activation voltage of the relay coil? What is the
maximum coil voltage of the relay? What is the typical resistance of
the relay coil?

I'm using the relay shown in this MK111 circuit...
http://www.vellemanusa.com/downloads...nual_mk111.pdf

PS -- Photo of relay and data sheet attached.

Relay characteristics aren't controlled closely. As long as they meet
the guaranteed specs, that's all that counts. Anything better than that
is OK. This means that the circuit you propose can have a different
delay if you substitute another relay, even if it is the same type.

Therefore, you really can't calculate the values unless you measure the
characteristics of the particular relay you are going to use. It would
be easier to just try different values of the parts until you get the
result you want. As someones else pointed out, even then the results are
likely to be inconsistent.

This is the problem that 555 timer ICs solve. Consider using one.

--
Jim Mueller

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.


Thanks Jim. I have no experience with 555 timers. Where would I find a basic circuit for this application using a 555?


We know the coil of your relay of choice is 12VDC, but not how much
current is required (resistance of coil, or spec current).

It could be as simple as an R/C plus a 555, plus a diode, or it might
need a transistor as well.

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

"Jim Thompson" wrote in message ...
On Fri, 6 Sep 2013 09:57:57 -0700, "Guv Bob"
wrote:

"Jim Mueller" wrote in message eb.com...
On Thu, 05 Sep 2013 13:47:53 -0700, Guv Bob wrote:

"Guv Bob" wrote in message
news "RosemontCrest" wrote in message
...
On 9/4/2013 3:40 PM, Guv Bob wrote:
My component level electronics is rusty, including RC circuit
calculations, having been doing module swapping for years. This is
probably a very simple question for the folks here....

Is this a reasonable circuit for a delay timer?

If so, how would I calculate the values of R &C for this...

1. Switch closes 2. After 5 seconds, the relay energizes and
remains energized until switch is opened.

Sketch...
http://img839.imageshack.us/img839/4650/uh3.gif

Thanks in advance!

Bob


What is the minimum activation voltage of the relay coil? What is the
maximum coil voltage of the relay? What is the typical resistance of
the relay coil?

I'm using the relay shown in this MK111 circuit...
http://www.vellemanusa.com/downloads...nual_mk111.pdf

PS -- Photo of relay and data sheet attached.

Relay characteristics aren't controlled closely. As long as they meet
the guaranteed specs, that's all that counts. Anything better than that
is OK. This means that the circuit you propose can have a different
delay if you substitute another relay, even if it is the same type.

Therefore, you really can't calculate the values unless you measure the
characteristics of the particular relay you are going to use. It would
be easier to just try different values of the parts until you get the
result you want. As someones else pointed out, even then the results are
likely to be inconsistent.

This is the problem that 555 timer ICs solve. Consider using one.

--
Jim Mueller

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.


Thanks Jim. I have no experience with 555 timers. Where would I find a basic circuit for this application using a 555?


We know the coil of your relay of choice is 12VDC, but not how much
current is required (resistance of coil, or spec current).

It could be as simple as an R/C plus a 555, plus a diode, or it might
need a transistor as well.

That would be great! The 12VDC relay coil requires 38ma to actuate.

On Fri, 06 Sep 2013 09:57:57 -0700, Guv Bob wrote:

snip


Thanks Jim. I have no experience with 555 timers. Where would I find a
basic circuit for this application using a 555?

Here's a data sheet: http://www.ti.com/lit/ds/symlink/lm555.pdf. It has
a number of generic circuits. What you want is a monostable circuit. It
can be set up to trigger from power-on or from a separate signal. Can
you modify the example circuit yourself or do you need help?

--
Jim Mueller

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.

On Fri, 6 Sep 2013 13:37:42 -0700, "Guv Bob"
wrote:

"Jim Thompson" wrote in message ...
On Fri, 6 Sep 2013 09:57:57 -0700, "Guv Bob"
wrote:

"Jim Mueller" wrote in message eb.com...
On Thu, 05 Sep 2013 13:47:53 -0700, Guv Bob wrote:

"Guv Bob" wrote in message
news "RosemontCrest" wrote in message
...
On 9/4/2013 3:40 PM, Guv Bob wrote:
My component level electronics is rusty, including RC circuit
calculations, having been doing module swapping for years. This is
probably a very simple question for the folks here....

Is this a reasonable circuit for a delay timer?

If so, how would I calculate the values of R &C for this...

1. Switch closes 2. After 5 seconds, the relay energizes and
remains energized until switch is opened.

Sketch...
http://img839.imageshack.us/img839/4650/uh3.gif

Thanks in advance!

Bob


What is the minimum activation voltage of the relay coil? What is the
maximum coil voltage of the relay? What is the typical resistance of
the relay coil?

I'm using the relay shown in this MK111 circuit...
http://www.vellemanusa.com/downloads...nual_mk111.pdf

PS -- Photo of relay and data sheet attached.

Relay characteristics aren't controlled closely. As long as they meet
the guaranteed specs, that's all that counts. Anything better than that
is OK. This means that the circuit you propose can have a different
delay if you substitute another relay, even if it is the same type.

Therefore, you really can't calculate the values unless you measure the
characteristics of the particular relay you are going to use. It would
be easier to just try different values of the parts until you get the
result you want. As someones else pointed out, even then the results are
likely to be inconsistent.

This is the problem that 555 timer ICs solve. Consider using one.

--
Jim Mueller

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.


Thanks Jim. I have no experience with 555 timers. Where would I find a basic circuit for this application using a 555?


We know the coil of your relay of choice is 12VDC, but not how much
current is required (resistance of coil, or spec current).

It could be as simple as an R/C plus a 555, plus a diode, or it might
need a transistor as well.

That would be great! The 12VDC relay coil requires 38ma to actuate.


Are you actually using a relay to power an LED, or is that just a
representative load?

For an LED only, you don't even need the relay. How much current in
the LED?

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

"Jim Mueller" wrote in message b.com...
On Fri, 06 Sep 2013 09:57:57 -0700, Guv Bob wrote:

snip


Thanks Jim. I have no experience with 555 timers. Where would I find a
basic circuit for this application using a 555?

Here's a data sheet: http://www.ti.com/lit/ds/symlink/lm555.pdf. It has
a number of generic circuits. What you want is a monostable circuit. It
can be set up to trigger from power-on or from a separate signal. Can
you modify the example circuit yourself or do you need help?

--
Jim Mueller

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.

Thanks, Jim, that's a big help. I'm afraid I do need more help. Someone also mentioned needing a diode. I'm pretty lost at the component level.

If it helps, the application is to energize a small LED for approx 5 seconds when 12VDC is applied to the input. After 5 seconds the LED should go off even though 12VDC is still on the input.

I don't have the LED current draw, but it's very small - probably on the order of 10ma.

Many thanks for this help!

Bob

"Jim Thompson" wrote in message ...
On Fri, 6 Sep 2013 13:37:42 -0700, "Guv Bob"
wrote:

"Jim Thompson" wrote in message ...
On Fri, 6 Sep 2013 09:57:57 -0700, "Guv Bob"
wrote:

"Jim Mueller" wrote in message eb.com...
On Thu, 05 Sep 2013 13:47:53 -0700, Guv Bob wrote:

"Guv Bob" wrote in message
news "RosemontCrest" wrote in message
...
On 9/4/2013 3:40 PM, Guv Bob wrote:
My component level electronics is rusty, including RC circuit
calculations, having been doing module swapping for years. This is
probably a very simple question for the folks here....

Is this a reasonable circuit for a delay timer?

If so, how would I calculate the values of R &C for this...

1. Switch closes 2. After 5 seconds, the relay energizes and
remains energized until switch is opened.

Sketch...
http://img839.imageshack.us/img839/4650/uh3.gif

Thanks in advance!

Bob


What is the minimum activation voltage of the relay coil? What is the
maximum coil voltage of the relay? What is the typical resistance of
the relay coil?

I'm using the relay shown in this MK111 circuit...
http://www.vellemanusa.com/downloads...nual_mk111.pdf

PS -- Photo of relay and data sheet attached.

Relay characteristics aren't controlled closely. As long as they meet
the guaranteed specs, that's all that counts. Anything better than that
is OK. This means that the circuit you propose can have a different
delay if you substitute another relay, even if it is the same type.

Therefore, you really can't calculate the values unless you measure the
characteristics of the particular relay you are going to use. It would
be easier to just try different values of the parts until you get the
result you want. As someones else pointed out, even then the results are
likely to be inconsistent.

This is the problem that 555 timer ICs solve. Consider using one.

--
Jim Mueller

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.


Thanks Jim. I have no experience with 555 timers. Where would I find a basic circuit for this application using a 555?


We know the coil of your relay of choice is 12VDC, but not how much
current is required (resistance of coil, or spec current).

It could be as simple as an R/C plus a 555, plus a diode, or it might
need a transistor as well.

That would be great! The 12VDC relay coil requires 38ma to actuate.


Are you actually using a relay to power an LED, or is that just a
representative load?

For an LED only, you don't even need the relay. How much current in
the LED?

Yes, just a small LED - probably around 10 ma. I just happen to have a relay I thought might be needed.

On 9/6/2013 9:00 PM, Guv Bob wrote:

"Jim Thompson" wrote in message ...
On Fri, 6 Sep 2013 13:37:42 -0700, "Guv Bob"
wrote:

"Jim Thompson" wrote in message ...
On Fri, 6 Sep 2013 09:57:57 -0700, "Guv Bob"
wrote:

"Jim Mueller" wrote in message eb.com...
On Thu, 05 Sep 2013 13:47:53 -0700, Guv Bob wrote:

"Guv Bob" wrote in message
news "RosemontCrest" wrote in message
...
On 9/4/2013 3:40 PM, Guv Bob wrote:
My component level electronics is rusty, including RC circuit
calculations, having been doing module swapping for years. This is
probably a very simple question for the folks here....

Is this a reasonable circuit for a delay timer?

If so, how would I calculate the values of R &C for this...

1. Switch closes 2. After 5 seconds, the relay energizes and
remains energized until switch is opened.

Sketch...
http://img839.imageshack.us/img839/4650/uh3.gif

Thanks in advance!

Bob


What is the minimum activation voltage of the relay coil? What is the
maximum coil voltage of the relay? What is the typical resistance of
the relay coil?

I'm using the relay shown in this MK111 circuit...
http://www.vellemanusa.com/downloads...nual_mk111.pdf

PS -- Photo of relay and data sheet attached.

Relay characteristics aren't controlled closely. As long as they meet
the guaranteed specs, that's all that counts. Anything better than that
is OK. This means that the circuit you propose can have a different
delay if you substitute another relay, even if it is the same type.

Therefore, you really can't calculate the values unless you measure the
characteristics of the particular relay you are going to use. It would
be easier to just try different values of the parts until you get the
result you want. As someones else pointed out, even then the results are
likely to be inconsistent.

This is the problem that 555 timer ICs solve. Consider using one.

--
Jim Mueller

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.


Thanks Jim. I have no experience with 555 timers. Where would I find a basic circuit for this application using a 555?


We know the coil of your relay of choice is 12VDC, but not how much
current is required (resistance of coil, or spec current).

It could be as simple as an R/C plus a 555, plus a diode, or it might
need a transistor as well.

That would be great! The 12VDC relay coil requires 38ma to actuate.


Are you actually using a relay to power an LED, or is that just a
representative load?

For an LED only, you don't even need the relay. How much current in
the LED?

Yes, just a small LED - probably around 10 ma. I just happen to have a relay I thought might be needed.

In that case, all you need is a simple comparator, perhaps an opamp
operating "open-loop" to drive the LED.

On 9/6/2013 8:59 PM, Guv Bob wrote:
"Jim Mueller" wrote in message b.com...
On Fri, 06 Sep 2013 09:57:57 -0700, Guv Bob wrote:

snip


Thanks Jim. I have no experience with 555 timers. Where would I find a
basic circuit for this application using a 555?

Here's a data sheet: http://www.ti.com/lit/ds/symlink/lm555.pdf. It has
a number of generic circuits. What you want is a monostable circuit. It
can be set up to trigger from power-on or from a separate signal. Can
you modify the example circuit yourself or do you need help?

--
Jim Mueller

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.

Thanks, Jim, that's a big help. I'm afraid I do need more help. Someone also mentioned needing a diode. I'm pretty lost at the component level.

The diode would be placed in parallel with the relay coil, if you needed
relay, which you don't.

If it helps, the application is to energize a small LED for approx 5 seconds when 12VDC is applied to the input. After 5 seconds the LED should go off even though 12VDC is still on the input.

That should be easy to do with a comparator and a simple RC circuit.

I don't have the LED current draw, but it's very small - probably on the order of 10ma.

Most LEDs will operate fine at 10 mA; typical maximum current is 20-30
mA steady-state.

Many thanks for this help!

Bob

On 9/6/2013 8:59 PM, Guv Bob wrote:
"Jim Mueller" wrote in message b.com...
On Fri, 06 Sep 2013 09:57:57 -0700, Guv Bob wrote:

snip


Thanks Jim. I have no experience with 555 timers. Where would I find a
basic circuit for this application using a 555?

Here's a data sheet: http://www.ti.com/lit/ds/symlink/lm555.pdf. It has
a number of generic circuits. What you want is a monostable circuit. It
can be set up to trigger from power-on or from a separate signal. Can
you modify the example circuit yourself or do you need help?

--
Jim Mueller

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.

Thanks, Jim, that's a big help. I'm afraid I do need more help. Someone also mentioned needing a diode. I'm pretty lost at the component level.

If it helps, the application is to energize a small LED for approx 5 seconds when 12VDC is applied to the input. After 5 seconds the LED should go off even though 12VDC is still on the input.

I don't have the LED current draw, but it's very small - probably on the order of 10ma.

Many thanks for this help!

Bob

Attached is admittedly quick-and-dirty, but it's ever-so-simple; no 555
timer involved. Most any garden-variety N-channel MOSFET with Vgs(on) ~=
4V will work for Q1, but performance may vary from FET to FET. Depending
on the Vgs(on) of the FET you select, you may want to fiddle with the
value of R1 to get as close to 5 seconds as you desire.

Change the value of R2 to increase or decrease the forward current of
the LED and resulting brightness.

On Fri, 6 Sep 2013 21:00:39 -0700, "Guv Bob"
wrote:


"Jim Thompson" wrote in message ...
On Fri, 6 Sep 2013 13:37:42 -0700, "Guv Bob"
wrote:

"Jim Thompson" wrote in message ...
On Fri, 6 Sep 2013 09:57:57 -0700, "Guv Bob"
wrote:

"Jim Mueller" wrote in message eb.com...
On Thu, 05 Sep 2013 13:47:53 -0700, Guv Bob wrote:

"Guv Bob" wrote in message
news "RosemontCrest" wrote in message
...
On 9/4/2013 3:40 PM, Guv Bob wrote:
My component level electronics is rusty, including RC circuit
calculations, having been doing module swapping for years. This is
probably a very simple question for the folks here....

Is this a reasonable circuit for a delay timer?

If so, how would I calculate the values of R &C for this...

1. Switch closes 2. After 5 seconds, the relay energizes and
remains energized until switch is opened.

Sketch...
http://img839.imageshack.us/img839/4650/uh3.gif

Thanks in advance!

Bob


What is the minimum activation voltage of the relay coil? What is the
maximum coil voltage of the relay? What is the typical resistance of
the relay coil?

I'm using the relay shown in this MK111 circuit...
http://www.vellemanusa.com/downloads...nual_mk111.pdf

PS -- Photo of relay and data sheet attached.

Relay characteristics aren't controlled closely. As long as they meet
the guaranteed specs, that's all that counts. Anything better than that
is OK. This means that the circuit you propose can have a different
delay if you substitute another relay, even if it is the same type.

Therefore, you really can't calculate the values unless you measure the
characteristics of the particular relay you are going to use. It would
be easier to just try different values of the parts until you get the
result you want. As someones else pointed out, even then the results are
likely to be inconsistent.

This is the problem that 555 timer ICs solve. Consider using one.

--
Jim Mueller

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.


Thanks Jim. I have no experience with 555 timers. Where would I find a basic circuit for this application using a 555?


We know the coil of your relay of choice is 12VDC, but not how much
current is required (resistance of coil, or spec current).

It could be as simple as an R/C plus a 555, plus a diode, or it might
need a transistor as well.

That would be great! The 12VDC relay coil requires 38ma to actuate.


Are you actually using a relay to power an LED, or is that just a
representative load?

For an LED only, you don't even need the relay. How much current in
the LED?

Yes, just a small LED - probably around 10 ma. I just happen to have a relay I thought might be needed.


Go to my website...

http://www.analog-innovations.com/

Select the S.E.D/Schematics link

Near the top of the list...

"5-Second_Timer.pdf"

Or a direct link if you have no interest in the hundreds of other
example schematics :-} ...

http://www.analog-innovations.com/SED/5-Second_Timer.pdf

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

On Fri, 06 Sep 2013 20:59:46 -0700, Guv Bob wrote:

"Jim Mueller" wrote in message
b.com...
On Fri, 06 Sep 2013 09:57:57 -0700, Guv Bob wrote:

snip


Thanks Jim. I have no experience with 555 timers. Where would I
find a basic circuit for this application using a 555?

Here's a data sheet: http://www.ti.com/lit/ds/symlink/lm555.pdf. It
has a number of generic circuits. What you want is a monostable
circuit. It can be set up to trigger from power-on or from a separate
signal. Can you modify the example circuit yourself or do you need
help?

--
Jim Mueller

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.

Thanks, Jim, that's a big help. I'm afraid I do need more help.
Someone also mentioned needing a diode. I'm pretty lost at the
component level.

If it helps, the application is to energize a small LED for approx 5
seconds when 12VDC is applied to the input. After 5 seconds the LED
should go off even though 12VDC is still on the input.

I don't have the LED current draw, but it's very small - probably on the
order of 10ma.

Many thanks for this help!

Bob

The circuit in the link from Jim Thompson, http://www.analog-
innovations.com/SED/5-Second_Timer.pdf, turns the LED on after 5 seconds
which is the opposite of what you want. To reverse this (one way of
several) is to disconnect R1 from +12V and connect it to pin 3 of the
555. Then, the cathode of the LED is disconnected from pin 3 and
connected to ground. The 555 is somewhat unique for an older part in
that it can source a substantial current as well as sink.

Manufacturer's data sheets show pin 5 bypassed to ground with 0.01uF
although I have seen many circuits without it. As usual, be sure the
power supply is bypassed.

D1 on the schematic is to quickly discharge C1 when the power is turned
off so that the circuit resets promptly. This depends on having enough
additional load to accomplish this. If you don't have another load, a
resistor from +12V to ground (on the timer side of the switch) will do
it. 47K would be a good value but it isn't at all critical.

Have fun,

--
Jim Mueller

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.

On 07 Sep 2013 20:21:35 GMT, Jim Mueller wrote:

On Fri, 06 Sep 2013 20:59:46 -0700, Guv Bob wrote:

"Jim Mueller" wrote in message
b.com...
On Fri, 06 Sep 2013 09:57:57 -0700, Guv Bob wrote:

snip


Thanks Jim. I have no experience with 555 timers. Where would I
find a basic circuit for this application using a 555?

Here's a data sheet: http://www.ti.com/lit/ds/symlink/lm555.pdf. It
has a number of generic circuits. What you want is a monostable
circuit. It can be set up to trigger from power-on or from a separate
signal. Can you modify the example circuit yourself or do you need
help?

--
Jim Mueller

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.

Thanks, Jim, that's a big help. I'm afraid I do need more help.
Someone also mentioned needing a diode. I'm pretty lost at the
component level.

If it helps, the application is to energize a small LED for approx 5
seconds when 12VDC is applied to the input. After 5 seconds the LED
should go off even though 12VDC is still on the input.

I don't have the LED current draw, but it's very small - probably on the
order of 10ma.

Many thanks for this help!

Bob

The circuit in the link from Jim Thompson, http://www.analog-
innovations.com/SED/5-Second_Timer.pdf, turns the LED on after 5 seconds
which is the opposite of what you want. To reverse this (one way of
several) is to disconnect R1 from +12V and connect it to pin 3 of the
555. Then, the cathode of the LED is disconnected from pin 3 and
connected to ground. The 555 is somewhat unique for an older part in
that it can source a substantial current as well as sink.

Huh?

The way I read Bob's OP...

http://img839.imageshack.us/img839/4650/uh3.gif

the relay closes after 5 seconds, activating the LED.

Did I miss a post reversing that?


Manufacturer's data sheets show pin 5 bypassed to ground with 0.01uF
although I have seen many circuits without it. As usual, be sure the
power supply is bypassed.

D1 on the schematic is to quickly discharge C1 when the power is turned
off so that the circuit resets promptly. This depends on having enough
additional load to accomplish this. If you don't have another load, a
resistor from +12V to ground (on the timer side of the switch) will do
it. 47K would be a good value but it isn't at all critical.

Have fun,

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

On Sat, 07 Sep 2013 13:35:25 -0700, Jim Thompson
wrote:

On 07 Sep 2013 20:21:35 GMT, Jim Mueller wrote:

On Fri, 06 Sep 2013 20:59:46 -0700, Guv Bob wrote:

"Jim Mueller" wrote in message
b.com...
On Fri, 06 Sep 2013 09:57:57 -0700, Guv Bob wrote:

snip


Thanks Jim. I have no experience with 555 timers. Where would I
find a basic circuit for this application using a 555?

Here's a data sheet: http://www.ti.com/lit/ds/symlink/lm555.pdf. It
has a number of generic circuits. What you want is a monostable
circuit. It can be set up to trigger from power-on or from a separate
signal. Can you modify the example circuit yourself or do you need
help?

--
Jim Mueller

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.

Thanks, Jim, that's a big help. I'm afraid I do need more help.
Someone also mentioned needing a diode. I'm pretty lost at the
component level.

If it helps, the application is to energize a small LED for approx 5
seconds when 12VDC is applied to the input. After 5 seconds the LED
should go off even though 12VDC is still on the input.

I don't have the LED current draw, but it's very small - probably on the
order of 10ma.

Many thanks for this help!

Bob

The circuit in the link from Jim Thompson, http://www.analog-
innovations.com/SED/5-Second_Timer.pdf, turns the LED on after 5 seconds
which is the opposite of what you want. To reverse this (one way of
several) is to disconnect R1 from +12V and connect it to pin 3 of the
555. Then, the cathode of the LED is disconnected from pin 3 and
connected to ground. The 555 is somewhat unique for an older part in
that it can source a substantial current as well as sink.

Huh?

The way I read Bob's OP...

http://img839.imageshack.us/img839/4650/uh3.gif

the relay closes after 5 seconds, activating the LED.

Did I miss a post reversing that?

---
Here's his original post:

"Names can be confusing, so here's what I'm doing....

http://img43.imageshack.us/img43/7434/wvm.gif

When 12VDC is applied to the input, I need a 12VDC output for 5
seconds. Then output will go back off and stay off until the input
goes to zero. Then cycle starts again."

--
JF

On Sun, 08 Sep 2013 12:48:57 -0500, John Fields
wrote:

On Sat, 07 Sep 2013 13:35:25 -0700, Jim Thompson
wrote:

On 07 Sep 2013 20:21:35 GMT, Jim Mueller wrote:

On Fri, 06 Sep 2013 20:59:46 -0700, Guv Bob wrote:

"Jim Mueller" wrote in message
b.com...
On Fri, 06 Sep 2013 09:57:57 -0700, Guv Bob wrote:

snip


Thanks Jim. I have no experience with 555 timers. Where would I
find a basic circuit for this application using a 555?

Here's a data sheet: http://www.ti.com/lit/ds/symlink/lm555.pdf. It
has a number of generic circuits. What you want is a monostable
circuit. It can be set up to trigger from power-on or from a separate
signal. Can you modify the example circuit yourself or do you need
help?

--
Jim Mueller

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.

Thanks, Jim, that's a big help. I'm afraid I do need more help.
Someone also mentioned needing a diode. I'm pretty lost at the
component level.

If it helps, the application is to energize a small LED for approx 5
seconds when 12VDC is applied to the input. After 5 seconds the LED
should go off even though 12VDC is still on the input.

I don't have the LED current draw, but it's very small - probably on the
order of 10ma.

Many thanks for this help!

Bob

The circuit in the link from Jim Thompson, http://www.analog-
innovations.com/SED/5-Second_Timer.pdf, turns the LED on after 5 seconds
which is the opposite of what you want. To reverse this (one way of
several) is to disconnect R1 from +12V and connect it to pin 3 of the
555. Then, the cathode of the LED is disconnected from pin 3 and
connected to ground. The 555 is somewhat unique for an older part in
that it can source a substantial current as well as sink.

Huh?

The way I read Bob's OP...

http://img839.imageshack.us/img839/4650/uh3.gif

the relay closes after 5 seconds, activating the LED.

Did I miss a post reversing that?

---
Here's his original post:

"Names can be confusing, so here's what I'm doing....

http://img43.imageshack.us/img43/7434/wvm.gif

When 12VDC is applied to the input, I need a 12VDC output for 5
seconds. Then output will go back off and stay off until the input
goes to zero. Then cycle starts again."

That doesn't match his original imageshack sketch.

So, in my circuit, just put the series R+LED from 555 output to
ground?

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

On Fri, 06 Sep 2013 21:18:08 -0700, RosemontCrest
wrote:

On 9/6/2013 8:59 PM, Guv Bob wrote:
"Jim Mueller" wrote in message b.com...
On Fri, 06 Sep 2013 09:57:57 -0700, Guv Bob wrote:

snip


Thanks Jim. I have no experience with 555 timers. Where would I find a
basic circuit for this application using a 555?

Here's a data sheet: http://www.ti.com/lit/ds/symlink/lm555.pdf. It has
a number of generic circuits. What you want is a monostable circuit. It
can be set up to trigger from power-on or from a separate signal. Can
you modify the example circuit yourself or do you need help?

--
Jim Mueller

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.

Thanks, Jim, that's a big help. I'm afraid I do need more help. Someone also mentioned needing a diode. I'm pretty lost at the component level.

The diode would be placed in parallel with the relay coil, if you needed
relay, which you don't.

If it helps, the application is to energize a small LED for approx 5 seconds when 12VDC is applied to the input. After 5 seconds the LED should go off even though 12VDC is still on the input.

That should be easy to do with a comparator and a simple RC circuit.

I don't have the LED current draw, but it's very small - probably on the order of 10ma.

Most LEDs will operate fine at 10 mA; typical maximum current is 20-30
mA steady-state.

Many thanks for this help!

Bob

---
Your circuit, Rosemount 1.asc, doesn't seem to work.

Guv Bob 2.asc seems to.

--
JF

On Sun, 08 Sep 2013 10:53:56 -0700, Jim Thompson
wrote:

On Sun, 08 Sep 2013 12:48:57 -0500, John Fields
wrote:

On Sat, 07 Sep 2013 13:35:25 -0700, Jim Thompson
wrote:

On 07 Sep 2013 20:21:35 GMT, Jim Mueller wrote:

On Fri, 06 Sep 2013 20:59:46 -0700, Guv Bob wrote:

"Jim Mueller" wrote in message
b.com...
On Fri, 06 Sep 2013 09:57:57 -0700, Guv Bob wrote:

snip


Thanks Jim. I have no experience with 555 timers. Where would I
find a basic circuit for this application using a 555?

Here's a data sheet: http://www.ti.com/lit/ds/symlink/lm555.pdf. It
has a number of generic circuits. What you want is a monostable
circuit. It can be set up to trigger from power-on or from a separate
signal. Can you modify the example circuit yourself or do you need
help?

--
Jim Mueller

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.

Thanks, Jim, that's a big help. I'm afraid I do need more help.
Someone also mentioned needing a diode. I'm pretty lost at the
component level.

If it helps, the application is to energize a small LED for approx 5
seconds when 12VDC is applied to the input. After 5 seconds the LED
should go off even though 12VDC is still on the input.

I don't have the LED current draw, but it's very small - probably on the
order of 10ma.

Many thanks for this help!

Bob

The circuit in the link from Jim Thompson, http://www.analog-
innovations.com/SED/5-Second_Timer.pdf, turns the LED on after 5 seconds
which is the opposite of what you want. To reverse this (one way of
several) is to disconnect R1 from +12V and connect it to pin 3 of the
555. Then, the cathode of the LED is disconnected from pin 3 and
connected to ground. The 555 is somewhat unique for an older part in
that it can source a substantial current as well as sink.

Huh?

The way I read Bob's OP...

http://img839.imageshack.us/img839/4650/uh3.gif

the relay closes after 5 seconds, activating the LED.

Did I miss a post reversing that?

---
Here's his original post:

"Names can be confusing, so here's what I'm doing....

http://img43.imageshack.us/img43/7434/wvm.gif

When 12VDC is applied to the input, I need a 12VDC output for 5
seconds. Then output will go back off and stay off until the input
goes to zero. Then cycle starts again."

That doesn't match his original imageshack sketch.

---
Aarghhh...

You're right. I got his two threads confused.
---


So, in my circuit, just put the series R+LED from 555 output to
ground?

---
Nope, what you have is just right.

--
JF

On 9/8/2013 1:33 PM, John Fields wrote:
On Fri, 06 Sep 2013 21:18:08 -0700, RosemontCrest
wrote:

On 9/6/2013 8:59 PM, Guv Bob wrote:
"Jim Mueller" wrote in message b.com...
On Fri, 06 Sep 2013 09:57:57 -0700, Guv Bob wrote:

snip


Thanks Jim. I have no experience with 555 timers. Where would I find a
basic circuit for this application using a 555?

Here's a data sheet: http://www.ti.com/lit/ds/symlink/lm555.pdf. It has
a number of generic circuits. What you want is a monostable circuit. It
can be set up to trigger from power-on or from a separate signal. Can
you modify the example circuit yourself or do you need help?

--
Jim Mueller

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.

Thanks, Jim, that's a big help. I'm afraid I do need more help. Someone also mentioned needing a diode. I'm pretty lost at the component level.

The diode would be placed in parallel with the relay coil, if you needed
relay, which you don't.

If it helps, the application is to energize a small LED for approx 5 seconds when 12VDC is applied to the input. After 5 seconds the LED should go off even though 12VDC is still on the input.

That should be easy to do with a comparator and a simple RC circuit.

I don't have the LED current draw, but it's very small - probably on the order of 10ma.

Most LEDs will operate fine at 10 mA; typical maximum current is 20-30
mA steady-state.

Many thanks for this help!

Bob

---
Your circuit, Rosemount 1.asc, doesn't seem to work.

Actually, it does work on my Digi Designer breadboard... at least during
the first time the switch is closed. If the switch is subsequently
opened then closed within a few seconds, it doesn't work. C1 remains
charged.

Attached is a revised schematic that does actually work provided that
the switch-open time is greater than ~1 second.


Guv Bob 2.asc seems to.

Thanks, everyone, for all the educational info. I will hang around here regularly now.

I got what I needed by buying a MK111 time kit and modifying it - ended up with a the Delay on Make (or Power On Delay) timer. To try and head off the questions about nominclature ... this type of relay delays the power coming on to the load for a preset time. That's why it's call an "On Delay" timer -- it delays the power when turned on.

The different here is that I'm using the NC contact on the relay instead of the usual NO contact. So the power to the load is "on" when the 555 circuit is energized (thru NC), and is then turned off when the relay is energized.

Anyway, back to the practical stuff...

I made a real mess of the first board, thanks to a new Weller soldering iron. Ended up digging out my old Radio Shack iron which worked 10 times better - same type and wattage as the Weller. Here's the soldering job on each board.... try not to laugh...
http://img401.imageshack.us/img401/6528/9oag.jpg

Anyway, I made the changes Spehro mentioned and it works perfectly!

First I snipped R3 out of the circut which caused the LED to act as a one-shot as needed. So with that good news, I added the jumper puting the relay in the circuit and I am in Fat City!

FYI, on the left is the assembled board from the kit. Right shows it with the jumper added.
http://img835.imageshack.us/img835/6691/0wxx.jpg
http://img17.imageshack.us/img17/4276/g1k.gif

Thanks again to all for this very educational journey!

Bob