need to turn switch on/off at 1 - 5 second intervals

The subject pretty well defines my quest: need to turn switch on/off at 1 - 5 second intervals
Here's some background; I have a thermoblock that generates steam that is
too *wet*. I'd like to mount a valve (solenoid?) between the water mains & the thermoblock that can be opened/closed at varying intervals. Can someone point me toward a VERY cheap way to do this?
Robert Harmon -- http://www.tinyurl.com/mb4uj - My coffee pages. http://www.tinyurl.com/2tnv87 - My 'Guidelines For Newbies' page. http://www.tinyurl.com/2cr3e2 - I have things for sale here.
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Robert Harmon wrote:

Generally speaking, things in this power and timing range (1-5 secs, AC Water solenoid) are cheapest when done mechanically. Think motor, cam and microswitch.
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Robert Harmon wrote:

Assuming you have a mains powered solenoid:
+12 ---+----------------------------+-------+ |a | | [D1] [Relay] [D2] | | |a +-----+-----------+---+ +-------+ | | | | | | [1K] --------- | | | | 8 4 | | | +--------|7 | | | | | | | | P | 555 | | | O<---+---|6 3|---+ |+ T | | | [100uF] | | | | | +----+---|2 | | | | 5 1 | | |+ --------- | [100uF] | | | | [.1uF] | | | | | Gnd ---+-----+-----------+---+
Use a wall wart 12V power supply like DCTX-1234 from Allelectronics and a relay with contacts suitable for your solenoid's current draw. Relay RLY-451 from Allelectronics will handle 30 amps, so it would work. The pot value is 100K.
Wire the relay contact in series with the solenoid and the mains. If you don't have a solenoid, scrounge one from an old clothes washer that is being thrown away.
Ed
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ehsjr wrote:

An equivalent adjustable commercial repeat cycle relay is available for about $54 - may not be "VERY cheap" http://macromatic.com/search/product/search.php?search=t&product=TR-53122-05 These are available 12/24/120V AC/DC and 240VAC for the timer, with isolated contacts.
New solenoid valves might start around $20 - depends on flow rate.
-- bud--
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