Hello, I'm new to this site and I am looking for a bit of help. I'm a mechanical engineer so my knowledge on practical electronic circuits is limited.
I am trying to install a control system on a project that I am doing. The project is as follows

1 - System is Tripped (switch tuned on)
2 - electric actuator (A) must be lowered till it's maximum position
3 - a delay of 1 to 2 min must occur
4 - Electric actuator (B) must be lowered to it's maximum position
5 - A delay of 1 to 2 min must occur
6 - electric actuator (B) must be raised
7 - once that is complete, electric actuator (A) must be raised
8 - system is back to original position and ready to be tripped again

I would also like to be able to do a system reset in case of power failure and such

I do not know wither to use a PLC or if this can be done using a combination of relays and time delay relays. I need the solution before the 15th of December. Any help would be appreciated. Thank you very much

 

Maybe using a 555 timer and a counter??

 

yeah, that might work, it's just that with the deadline approaching I need a failsafe approach

something easy and packaged in modules. A plc sounds very clean, but how hard are they to program? I'm sorry for my lack of knowledge on the subject

 

If it were me I'd throw a small 8 bit micro at it. However, it sounds like you have never worked with anything like this. Not that it's extremely difficult... there's just a bit of a learning curve associated with it. Considering your deadline I would think a series of 555's along with some circuitry to drive relays would be your "failsafe".

 

With the deadline, I'd go with time-delay relays. No programming, no time constants to calculate, just plug & play.

 

I'd agree with that...

One issue might be getting time delayed relays in time. You can pick a 555 and passive components up at any radio shack but I would expect to have to mail order time delayed relays.

 

Thanks a lot buddy, I would like to go with an 8 bit or some form of plc. do you know of any good sites that would have info on how to set up basic plc circuits? I would also need the same for the 555 solution.

How easily are plc's to buy? would a specialized electronic store carry them in your opinion?

thanks again for your help
Jonathan

 

There are many flavors of microcontrollers out there... If I were doing the project and unit cost was of little concern I would simply choose the microcontroller in which I am most familiar. For me, this would be microchip (www.microchip.com) or TI (www.texasinstruments.com). Components can be purchased through many distributors. My favorite is Digi-Key (www.digikey.com). If you've never done this before I would recommend you NOT take this direction.

You should probably look at something a bit simpler. Try the basic stamp (www.parallax.com) or the basicx (www.basicx.com). The latter is far superior... but lacks in examples/documentation when compared to the former.

If you purchased a development board I would think you could get it delivered and construct your project in time.

 

If you don't know about PIC try using PICAXE that can be directly programmable in BASIC, a really easy to understand language.