Looking for the Electrical Gadget Master Among Us

[Michael Kadillak]

I have a requirement for an unusual electrical gadget that is IF it exists. What I need is a timed switch that I could use to turn on and off the power supply to another electrical devise at regular increments. I would like to be able to set it to have the power come on for one minute every 5,10 or 15 minutes. I have seen the switches for leaving your house lights on when you are out of town, but it cannot open and close as frequently as I need. Anyone know of such a device that would fit the billing? The application is photographically related to the darkroom.

Thanks in advance!

[Dan Fromm]

Michael, years ago when I was building an automatic water changing system for my fish room, I faced a similar program. My solution was a timer consisting of a clock motor turning a shaft with pairs of cams that bore on microswitches. I bought the timer I needed from Herbach & Rademan, now accessible as www. herbach.com. This link http://www.herbach.com/Merchant2/mer...R+Series+-+RPH
will get you to a single gang timer that opens and closes a circuit once an hour; H&R has others. The one I bought has two pairs of cams on one shaft, they used to sell 'em with as many as 24. Talk things over with H&R.

Cheers,

Dan

Yes, I know, its basically 19th century technology. Apt, eh?

[Eric Woodbury]

You might be able to do it with X10 (that house control stuff) and a computer to control it. Otherwise, try industrial controls. What's that big electrical stuff industrial control catalog?

[Jim Rice]

How accurate does it need to be? How consistent? How much power does it need to provide?

[Eric James]

Not sure if this is what you have in mind or if it fits your budget:

http://www.icca.invensys.com/paragon/ec4000_series.htm

Their price list suggests that it retails for less than $250.

http://www.icca.invensys.com/support...ceList2006.pdf

[Randy H]

Dan has the right idea. You can set the cammed micro-switches at very precise time intervals, varying from seconds to hours and everything in between. Years ago, I worked at a place that used these, and we used to scavange parts and build strobe lights from them. (drug-oriented, then on to disco-man) We set up six and eight switches per unit, and ran household lamps placed around the room, off the hot side of each. If the link he gave doesn't provide the info you need, check out McMaster-Carr and look up micro-switches.

[Jim Rice]

I'm thinking something along the lines of a couple of 555s if precision isn't paramount. Consistency will drift over time, but rather slowly. Trim pots can compensate, but are fiddly. Current draw will determine how heavy a relay we will need. Drop me a line.

[Gordon Moat]

Nikon make a device called an Intervalometer, though it is somewhat dedicated to working their cameras, and only works up to 27 hours. However, when searching for the details on these devices, I came across:

http://www.bmumford.com/photo/camctlr.html

Seems like something like this might work. I don't understand exactly what you want to accomplish, but this has some finite control to it.

Ciao!

Gordon Moat
A G Studio

[Michael Kadillak]

If I can be perfectly frank about the application that I am pursuing it could greatly assist in the solution.

I want to use the electrical switch to take a conventional interval gaseous burst timer that has independent switching for burst duration and interval (time between bursts) to test the application for stand or extreme minimal development using gaseous burst agitation for sheet film development.

The burst time on the interval timer is fine but the maximum interval is 60 seconds. With extreme minimal or stand development I want the flexibility to go anywhere between 5 minutes to as long as 15 minutes between agitation (bursts of nitrogen). Turning off the power to the interval timer allows me to overcome the limitations of the unit and should be the best solution as I do not want to have to stand there and turn on and off the interval timer. I would rather have a power switch to accomplish that function.

One example would have the power comes on for 30 seconds (when the gas bursts would take place to agitate the film in the developer) every 10 minutes for an hour when I would come back into the darkroom and turn the interval timer off as the development would be concluded.

Hope that helps,

Thanks

[Henry Ambrose]

How about a greenhouse timer?

http://homeharvest.com/climatecontroltimers.htm