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LSMFT

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Oct 18, 2010, 8:08:12 PM10/18/10
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I'm trying to find a timer to do what I want. Descriptions on the
internet are sadly inadaquate.
I want a timer that if it has input, say from a thermostat, to come on
for a set time (2 to 5 minutes) and cut off. And I want it to do this
every 15 minutes to 2 hours. What kind of timer do I need.
I don't mind wiring an octal socket it they come that way.

--
LSMFT

Simple job, assist the assistant of the physicist.

Jeff Liebermann

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Oct 18, 2010, 8:32:46 PM10/18/10
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On Mon, 18 Oct 2010 20:08:12 -0400, LSMFT <bol...@aol.com> wrote:

>I'm trying to find a timer to do what I want.

I have the same problem with kids, co-workers, sub-contractors, and
government agencies. They never seem to do what I want.

>Descriptions on the
>internet are sadly inadaquate.

You're not doing much better.
Input specs?
Output specs?
Power specs?
Definition of operation?
Max cost?
Quantity?
Timing adjustment or fixed?
Adjustment ranges?
Digital or analog?
Accuracy?

>I want a timer that if it has input, say from a thermostat, to come on
>for a set time (2 to 5 minutes) and cut off. And I want it to do this
>every 15 minutes to 2 hours. What kind of timer do I need.

Not a very good description. Does the timer sample the thermostat
output for the full duration of 2 to 5 minutes, or does the input need
to be there for the full 2 to 5 minutes? If the thermostat comes on
outside of the 2 to 5 minute window, what happens to the output? What
does the output do during this time? Stay on or drop out?

You probably need two timers. The 15 min to 2 hr timer enables the 2
to 5 minute timer, which then looks for an input when enabled. I have
no clue if you want 12V, 24V, 117V, AC or DC to run this thing, or
what manner of load, so I can't scribble a suitable circuit. A dual
555 type timer and a relay might work.

>I don't mind wiring an octal socket it they come that way.

DIN rail is the current fashion. Octal socket timers are rather
antiquated. See if this jogs your imagination:
<http://www.bb-elec.com/bb-elec/literature/105A_820_Series.pdf>
If you have money and want versatility, I suggest a PLC (programmable
logic controller) what can be trained to do almost anything you
describe with a ladder diagram.
<http://www.bb-elec.com/product_multi_family.asp?MultiFamilyId=39&Trail=158&TrailType=Main>


--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

LSMFT

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Oct 18, 2010, 8:45:37 PM10/18/10
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I'm working with 120 volts. The gate is thermostat closed or 120
applied. When closed, start 2 to 5 minute timer. If set for 3 minutes,
keeps contacts closed for 3 minutes as along as the gate is closed.
Otherwise do nothing or drop out if gates opens.
If gate is still closed do it again in 30 minutes to 2 hours, otherwise
do nothing.

LSMFT

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Oct 18, 2010, 8:46:38 PM10/18/10
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The load is a circulator 120 VAC.

LSMFT

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Oct 18, 2010, 8:48:18 PM10/18/10
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Can a programmable thermostat do this? I thought not.

LSMFT

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Oct 19, 2010, 8:21:37 AM10/19/10
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How about two re-triggerable one shots with variable delay shutoff in
series.

Art Todesco

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Oct 19, 2010, 8:44:57 AM10/19/10
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On 10/18/2010 8:08 PM, LSMFT wrote:
> I'm trying to find a timer to do what I want. Descriptions on the
> internet are sadly inadaquate.
> I want a timer that if it has input, say from a thermostat, to come on
> for a set time (2 to 5 minutes) and cut off. And I want it to do this
> every 15 minutes to 2 hours. What kind of timer do I need.
> I don't mind wiring an octal socket it they come that way.
>
If you're into building it yourself, here's a link to a schematic:
http://www.zen22142.zen.co.uk/Circuits/Timing/ivt.htm


nesesu

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Oct 19, 2010, 10:35:14 AM10/19/10
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Ha! Just what the OP needs.

Neil S.

LSMFT

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Oct 19, 2010, 12:59:17 PM10/19/10
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I would have no problem building it. That's what my trade used to be.

David Nebenzahl

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Oct 19, 2010, 1:13:29 PM10/19/10
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On 10/19/2010 5:44 AM Art Todesco spake thus:

Wouldn't that be accomplished just as well and much more simply with a
single 555 timer?


--
The fashion in killing has an insouciant, flirty style this spring,
with the flaunting of well-defined muscle, wrapped in flags.

- Comment from an article on Antiwar.com (http://antiwar.com)

Art Todesco

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Oct 20, 2010, 8:25:34 AM10/20/10
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On 10/19/2010 1:13 PM, David Nebenzahl wrote:
> On 10/19/2010 5:44 AM Art Todesco spake thus:
>
>> On 10/18/2010 8:08 PM, LSMFT wrote:
>>
>>> I'm trying to find a timer to do what I want. Descriptions on the
>>> internet are sadly inadaquate. I want a timer that if it has input,
>>> say from a thermostat, to come on for a set time (2 to 5 minutes)
>>> and cut off. And I want it to do this every 15 minutes to 2 hours.
>>> What kind of timer do I need. I don't mind wiring an octal socket
>>> it they come that way.
>>
>> If you're into building it yourself, here's a link to a schematic:
>> http://www.zen22142.zen.co.uk/Circuits/Timing/ivt.htm
>
> Wouldn't that be accomplished just as well and much more simply with a
> single 555 timer?
You might be able to do it with a single 555, but this one was already
designed and was easily adjustable for each part of the cycle.

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