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.
I have the same problem with kids, co-workers, sub-contractors, and government agencies. They never seem to do what I want.
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?
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.DIN rail is the current fashion. Octal socket timers are rather antiquated. See if this jogs your imagination:
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.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
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 Simple job, assist the assistant of the physicist.
The load is a circulator 120 VAC.
-- LSMFT Simple job, assist the assistant of the physicist.
Can a programmable thermostat do this? I thought not.
-- LSMFT Simple job, assist the assistant of the physicist.
How about two re-triggerable one shots with variable delay shutoff in series.
-- LSMFT Simple job, assist the assistant of the physicist.
If you're into building it yourself, here's a link to a schematic:
t I want. Descriptions on the
Ha! Just what the OP needs.
Neil S.
want. Descriptions on the
schematic:
I would have no problem building it. That's what my trade used to be.
-- LSMFT Simple job, assist the assistant of the physicist.
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)
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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