Help designing an 'reset' hourly timer... 555??

Greetings everyone.

I have a number of network unreliable network appliances scattered out
across campus that have to be visited often, and the reset button
pressed. Some days I spend a lot of time doing this.

I'd like to build up a simple timer circuit that would generate a
positve pulse of non-critical duration, say 2 seconds, every hour or
so. The hourly pulse should be 'astable', i.e. i'd like it to occur
over and over, every hour or so. I'll take the pulse and use it to
trigger a circuit to close a relay, to which i will wire the leads of
the reset switch. Automate pressing the reset switch...

I did a little TTL design many years ago, but i don't remember much
about it.. It's been a long time.

If some kind soul could sorta get me started here, I'd sure appreciate
it. I may need to build up several of these if this works out..

Kindest regards,
Russ

 

[John Fields]

On Sat, 23 Apr 2005 17:07:30 -0400, newsuser@soco.wcu.edu wrote:

Greetings everyone.

I have a number of network unreliable network appliances scattered out
across campus that have to be visited often, and the reset button
pressed. Some days I spend a lot of time doing this.

I'd like to build up a simple timer circuit that would generate a
positve pulse of non-critical duration, say 2 seconds, every hour or
so. The hourly pulse should be 'astable', i.e. i'd like it to occur
over and over, every hour or so. I'll take the pulse and use it to
trigger a circuit to close a relay, to which i will wire the leads of
the reset switch. Automate pressing the reset switch...

I did a little TTL design many years ago, but i don't remember much
about it.. It's been a long time.

If some kind soul could sorta get me started here, I'd sure appreciate
it. I may need to build up several of these if this works out..

---
Here ya go...

+---------+----+-------+
| Vcc | | | +V
[1M] | +-->[1M] [0.36ľF] |
| [100K] | | HC4060 +-------+
| | +------+-------+-----------+ |K | O----->C
+-------|Rs Rtc Ctc | [1N4148] [COIL]- - -|
| | | | | O--> |
+--|MR Q13 Q4 Q3 | +-------+ |
| +------------+----+-----+--+ | +---------->NO
| | | | C
+---[1N4148>]---+ | +--[510]--B 2N4401
| | E
+---[1N4148>]--------+ |
GND


The one Meg pot should be set about half-way through its range, to
about 500k, to set the oscillator frequency to 2.275Hz. The 0.36ľF cap
should be polyester film. With a 5V supply for Vcc, base current into
the 2N4401 will be about 10mA, so for a forced beta of 10, you'd like
a relay with 100mA or less of coil current. No big deal, though, just
be aware that the 2N4401 is rated for a maximum collector current of
0.6mA, so you need to stay substantially below that.

--
John Fields
Professional Circuit Designer

 

[mike]

John Fields wrote:

On Sat, 23 Apr 2005 17:07:30 -0400, newsuser@soco.wcu.edu wrote:


Greetings everyone.

I have a number of network unreliable network appliances scattered out
across campus that have to be visited often, and the reset button
pressed. Some days I spend a lot of time doing this.

I'd like to build up a simple timer circuit that would generate a
positve pulse of non-critical duration, say 2 seconds, every hour or
so. The hourly pulse should be 'astable', i.e. i'd like it to occur
over and over, every hour or so. I'll take the pulse and use it to
trigger a circuit to close a relay, to which i will wire the leads of
the reset switch. Automate pressing the reset switch...

I did a little TTL design many years ago, but i don't remember much
about it.. It's been a long time.

If some kind soul could sorta get me started here, I'd sure appreciate
it. I may need to build up several of these if this works out..


---
Here ya go...

+---------+----+-------+
| Vcc | | | +V
[1M] | +-->[1M] [0.36ľF] |
| [100K] | | HC4060 +-------+
| | +------+-------+-----------+ |K | O----->C
+-------|Rs Rtc Ctc | [1N4148] [COIL]- - -|
| | | | | O--> |
+--|MR Q13 Q4 Q3 | +-------+ |
| +------------+----+-----+--+ | +---------->NO
| | | | C
+---[1N4148>]---+ | +--[510]--B 2N4401
| | E
+---[1N4148>]--------+ |
GND


The one Meg pot should be set about half-way through its range, to
about 500k, to set the oscillator frequency to 2.275Hz. The 0.36ľF cap
should be polyester film. With a 5V supply for Vcc, base current into
the 2N4401 will be about 10mA, so for a forced beta of 10, you'd like
a relay with 100mA or less of coil current. No big deal, though, just
be aware that the 2N4401 is rated for a maximum collector current of
0.6mA, so you need to stay substantially below that.

Sure sounds low for max collector current. You sure about that?

Depending on how the reset circuit is designed, you may be able to use
an optoisolator instead of the relay. Cheaper, easier to build.
Guessing that the reset might be a closure to ground, again depending on
the value of the pullup, you may be able to use a diode for the reset
and power the thing off the reset current...depending...
mike

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[petrus bitbyter]

<newsuser@soco.wcu.edu> schreef in bericht
news:1ndl61ld3f4g6mj43po2kor1s2ij4m83lt@4ax.com...

Greetings everyone.

I have a number of network unreliable network appliances scattered out
across campus that have to be visited often, and the reset button
pressed. Some days I spend a lot of time doing this.

I'd like to build up a simple timer circuit that would generate a
positve pulse of non-critical duration, say 2 seconds, every hour or
so. The hourly pulse should be 'astable', i.e. i'd like it to occur
over and over, every hour or so. I'll take the pulse and use it to
trigger a circuit to close a relay, to which i will wire the leads of
the reset switch. Automate pressing the reset switch...

I did a little TTL design many years ago, but i don't remember much
about it.. It's been a long time.

If some kind soul could sorta get me started here, I'd sure appreciate
it. I may need to build up several of these if this works out..

Kindest regards,
Russ

Russ,

Their are more ways to skin a cat. If you want to stay in the TTL-like
components you can use a 556 (dual 555) and two 4-bit counters like the
LS163. Connect the latter to make an 8-bit counter. Use one timer as a clock
by making an astable multivibrator with a period of about 14s. Use this to
clock the 8-bit counter. The ripple carry output of the counter should
trigger the the second timer which is a monostable with a time of the 2s you
need for the reset.

I've heard about monostables that can be programmed for an hour or so but I
never saw them.

A low component count solution would be an eight pins PIC or AVR, but you
will need some skills and (little) equipment to program them. If you need -
let's say - twenty of them it may be worthwhile to have a look at them.

The best solution of course is to find out what causes the problem and
remove that cause. However, I know all too well that it's not always
possible.

petrus bitbyter.

 

[Chris]

<newsuser@soco.wcu.edu> wrote in message
news:1ndl61ld3f4g6mj43po2kor1s2ij4m83lt@4ax.com...

Greetings everyone.

I have a number of network unreliable network appliances scattered out
across campus that have to be visited often, and the reset button
pressed. Some days I spend a lot of time doing this.

I'd like to build up a simple timer circuit that would generate a
positve pulse of non-critical duration, say 2 seconds, every hour or
so. The hourly pulse should be 'astable', i.e. i'd like it to occur
over and over, every hour or so. I'll take the pulse and use it to
trigger a circuit to close a relay, to which i will wire the leads of
the reset switch. Automate pressing the reset switch...

I did a little TTL design many years ago, but i don't remember much
about it.. It's been a long time.

If some kind soul could sorta get me started here, I'd sure appreciate
it. I may need to build up several of these if this works out..

Kindest regards,
Russ

As a suggestion.

There are plug-in electrical timeclocks available with 4 segments to the
hour. By pressing in each 4th segment you would achieve a 1 hour timing.
This pulse although 15 minutes long could then energise a 12V transformer
with the output going through a diode, a 2000uF cap and a 12V relay in
series. Should give a couple of seconds, connect a bleed off resistor across
cap.

Cheers.

 

[Fred Bloggs]

John Fields wrote:

On Sat, 23 Apr 2005 17:07:30 -0400, newsuser@soco.wcu.edu wrote:


Greetings everyone.

I have a number of network unreliable network appliances scattered out
across campus that have to be visited often, and the reset button
pressed. Some days I spend a lot of time doing this.

I'd like to build up a simple timer circuit that would generate a
positve pulse of non-critical duration, say 2 seconds, every hour or
so. The hourly pulse should be 'astable', i.e. i'd like it to occur
over and over, every hour or so. I'll take the pulse and use it to
trigger a circuit to close a relay, to which i will wire the leads of
the reset switch. Automate pressing the reset switch...

I did a little TTL design many years ago, but i don't remember much
about it.. It's been a long time.

If some kind soul could sorta get me started here, I'd sure appreciate
it. I may need to build up several of these if this works out..


---
Here ya go...

+---------+----+-------+
| Vcc | | | +V
[1M] | +-->[1M] [0.36ľF] |
| [100K] | | HC4060 +-------+
| | +------+-------+-----------+ |K | O----->C
+-------|Rs Rtc Ctc | [1N4148] [COIL]- - -|
| | | | | O--> |
+--|MR Q13 Q4 Q3 | +-------+ |
| +------------+----+-----+--+ | +---------->NO
| | | | C
+---[1N4148>]---+ | +--[510]--B 2N4401
| | E
+---[1N4148>]--------+ |
GND


The one Meg pot should be set about half-way through its range, to
about 500k, to set the oscillator frequency to 2.275Hz. The 0.36ľF cap
should be polyester film. With a 5V supply for Vcc, base current into
the 2N4401 will be about 10mA, so for a forced beta of 10, you'd like
a relay with 100mA or less of coil current. No big deal, though, just
be aware that the 2N4401 is rated for a maximum collector current of
0.6mA, so you need to stay substantially below that.

Looks like Q3 is activating the relay every 3.5 seconds-I think you want
Q13 driving the 2N4401 base and this will last until Q4 goes H again
about 7 seconds later, when the whole thing MR's and starts over.

 

[John Fields]

On Sat, 23 Apr 2005 18:30:11 -0700, mike <spamme0@netscape.net> wrote:

John Fields wrote:
On Sat, 23 Apr 2005 17:07:30 -0400, newsuser@soco.wcu.edu wrote:


Greetings everyone.

I have a number of network unreliable network appliances scattered out
across campus that have to be visited often, and the reset button
pressed. Some days I spend a lot of time doing this.

I'd like to build up a simple timer circuit that would generate a
positve pulse of non-critical duration, say 2 seconds, every hour or
so. The hourly pulse should be 'astable', i.e. i'd like it to occur
over and over, every hour or so. I'll take the pulse and use it to
trigger a circuit to close a relay, to which i will wire the leads of
the reset switch. Automate pressing the reset switch...

I did a little TTL design many years ago, but i don't remember much
about it.. It's been a long time.

If some kind soul could sorta get me started here, I'd sure appreciate
it. I may need to build up several of these if this works out..


---
Here ya go...

+---------+----+-------+
| Vcc | | | +V
[1M] | +-->[1M] [0.36ľF] |
| [100K] | | HC4060 +-------+
| | +------+-------+-----------+ |K | O----->C
+-------|Rs Rtc Ctc | [1N4148] [COIL]- - -|
| | | | | O--> |
+--|MR Q13 Q4 Q3 | +-------+ |
| +------------+----+-----+--+ | +---------->NO
| | | | C
+---[1N4148>]---+ | +--[510]--B 2N4401
| | E
+---[1N4148>]--------+ |
GND


The one Meg pot should be set about half-way through its range, to
about 500k, to set the oscillator frequency to 2.275Hz. The 0.36ľF cap
should be polyester film. With a 5V supply for Vcc, base current into
the 2N4401 will be about 10mA, so for a forced beta of 10, you'd like
a relay with 100mA or less of coil current. No big deal, though, just
be aware that the 2N4401 is rated for a maximum collector current of
0.6mA, so you need to stay substantially below that.


Sure sounds low for max collector current. You sure about that?

---
Trypo... Should be 0.6A, thanks.
---

Depending on how the reset circuit is designed, you may be able to use
an optoisolator instead of the relay. Cheaper, easier to build.
Guessing that the reset might be a closure to ground, again depending on
the value of the pullup, you may be able to use a diode for the reset
and power the thing off the reset current...depending...
mike

--
John Fields
Professional Circuit Designer

 

[John Fields]

On Sun, 24 Apr 2005 14:39:51 GMT, Fred Bloggs <nospam@nospam.com>
wrote:

John Fields wrote:
On Sat, 23 Apr 2005 17:07:30 -0400, newsuser@soco.wcu.edu wrote:


Greetings everyone.

I have a number of network unreliable network appliances scattered out
across campus that have to be visited often, and the reset button
pressed. Some days I spend a lot of time doing this.

I'd like to build up a simple timer circuit that would generate a
positve pulse of non-critical duration, say 2 seconds, every hour or
so. The hourly pulse should be 'astable', i.e. i'd like it to occur
over and over, every hour or so. I'll take the pulse and use it to
trigger a circuit to close a relay, to which i will wire the leads of
the reset switch. Automate pressing the reset switch...

I did a little TTL design many years ago, but i don't remember much
about it.. It's been a long time.

If some kind soul could sorta get me started here, I'd sure appreciate
it. I may need to build up several of these if this works out..


---
Here ya go...

+---------+----+-------+
| Vcc | | | +V
[1M] | +-->[1M] [0.36ľF] |
| [100K] | | HC4060 +-------+
| | +------+-------+-----------+ |K | O----->C
+-------|Rs Rtc Ctc | [1N4148] [COIL]- - -|
| | | | | O--> |
+--|MR Q13 Q4 Q3 | +-------+ |
| +------------+----+-----+--+ | +---------->NO
| | | | C
+---[1N4148>]---+ | +--[510]--B 2N4401
| | E
+---[1N4148>]--------+ |
GND


The one Meg pot should be set about half-way through its range, to
about 500k, to set the oscillator frequency to 2.275Hz. The 0.36ľF cap
should be polyester film. With a 5V supply for Vcc, base current into
the 2N4401 will be about 10mA, so for a forced beta of 10, you'd like
a relay with 100mA or less of coil current. No big deal, though, just
be aware that the 2N4401 is rated for a maximum collector current of
0.6mA, so you need to stay substantially below that.


Looks like Q3 is activating the relay every 3.5 seconds-I think you want
Q13 driving the 2N4401 base and this will last until Q4 goes H again
about 7 seconds later, when the whole thing MR's and starts over.

---
YOW!!! Helluva good catch, thanks!

I think I'd rather use Q13 and Q3 for the reset, though, and shorten
up the relay ON time to be closer to the OP's 2s.

Like this:

+---------+----+-------+
| Vcc | | | +V
[1M] | +-->[1M] [0.36ľF] |
| [100K] | | HC4060 +-------+
| | +------+-------+------+ |K | O----->C
+-------|Rs Rtc Ctc | [1N4148] [COIL]- - -|
| | | | | O--> |
+--|MR Q13 Q3 | +-------+ |
| +------------+----+---+ | +---------->NO
| | | C
+---[1N4148>]---+---------[510]--B 2N4401
| | E
+---[1N4148>]--------+ |
GND

Thanks again,
--
John Fields
Professional Circuit Designer