SparkFun Forums

[nicte83]

Hi,

I have zero experience, but am not adverse to learning. I work in a laboratory. One of our tests uses a vacuum pump for either 1 minute or two minutes. Right now it is plugged into a power strip that I switch on and off.. which means I have to babysit it which digs into my efficiency quite a bit.

I want to create something that functions like the belkin conserve socket (http://www.amazon.com/Belkin-Conserve-S ... B003P2UMS0) - only with 1 & 2 minutes, versus the times they have.

I have been browsing around, and maybe picaxe? maybe something with the powerswitch tail II?

I really don't know what I need to get started. Please give me some advice as to how you think I should approach this project?

[lyndon]

Building a timer with two fixed times is pretty easy, but it depends on your background. Can you program? How accurate does the timer need to be?

The solution may be either a simple Arduino-type control (accurate, but requires programming skills) or building from a schematic on the web (not as accurate, but no programming needed).

Here Is a simple demo I made that switches a solenoid valve on for a preset time. Probably took about 5 minutes of programming with an off the shelf board.

OTOH, what's wrong with off the shelf timers? They are pretty cheap.

[nicte83]

If you could find me an off the shelf timer that shuts off the power at one and two minutes you would be my hero, I have looked all the places I know to go and come up empty..

It needs to be fairly accurate. Going over by a few seconds is not a problem, but under would be. It must be consistently repeatable.

I have never programmed like this, I can use xhtml/css, manipulate javascript and do some php. I don't mind learning a new thing.

[Mee_n_Mac]

If you don't need high precision timing ...
http://www.zoro.com/i/G1835206/?category=4793

Spring Wound Timer, Timing Range 5 Minutes, Contact Form SPST, Power Rating @ 125 VAC 1 HP, Power Rating @ 250 VAC 2 HP, Load Capacity @ 125 VAC 20 (Inductive)/7 (Tungsten) Amps, Load Capacity @ 250 VAC 10 Amps, Load Capacity @ 277 VAC 10 Amps, Hold Feature No, Decorator, Mechanical, 2 1/2 Inches Deep Junction Box, Ivory

[nicte83]

That could work, but I would like to keep exploring my options - as I have to "sell" the method to my bosses!

[Mee_n_Mac]

You could look at the various count-down timer kits and then couple one of those with a relay or the powerswitch tail. But if your bosses are like my corporate hierarchy, they'll want something UL approved.

[lyndon]

What's your budget for this?
There is an eBay timer for under $5. AKA "you pays your money and you takes your chances..."

You could use an industrial timer for $69. Will probably work as advertised and may need some connection to A/C and power output, but probably do what you need for $100 all in. Simpler, cheaper version also available.
Timing is one of the most common process control functions, so timers of all flavors are generally readily available.

[edit] Sorry, I was thinking 1-2 seconds instead of 1-2 minutes, but the comment above still applies. Automation Direct has dozens or hundreds of timers and many of them are square in the range you need.

Or an Arduino mini with a relay and a couple of pushbuttons for around $50 total would probably do it. The DIY way usually isn't as cheap as it first seems. If you can handle Javascript & PHP you should be able to manage enough C to get a timer working.

I can also build you one, but any of the above options would probably be cheaper.

[nicte83]

Thank you for your input. Now I just need to get approval.

[lyndon]

Which of the suggestions did you choose? If it's the Chinese eBay timers, I really want to know if they work well.

[edit]
And if you need help wiring everything up, just post here or PM me.

Thank you for your input. Now I just need to get approval.

[n1ist]

I use Omron HC3R timers for life-testing and similar controls in the lab. Programmable on and off times from seconds to hours. The ones I use have a 120VAC coil, and I drive a contactor or relay to control heavy loads.
/mike