LSMFT wrote:
LSMFT wrote:
Jeff Liebermann wrote:
On Mon, 18 Oct 2010 20:08:12 -0400, 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=15 8&TrailType=Main




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.



The load is a circulator 120 VAC.

Can a programmable thermostat do this? I thought not.

--
LSMFT

Simple job, assist the assistant of the physicist.