Timing Circuit with Relay

[Coded_Bananas]

Hi, I was hoping I could get some assistance from someone on a halloween project I was doing. I am trying to make a simple circuit to move a spider 4ft up and down a wall. I have made a dead simple circuit using a relay and two microswitches that simply reverses the polarity to the motor to make the spider move up and down.

This however requires the microswitches to be pushed as the spider reaches the correct position, still simple but I prefer neatness! So I was thinking a timing circuit with the 555 timer could energise the relay then de-energise it. However i'm unsure how to do this properly. I want the motor to run for probably about 5-10secs each way on a constant up and down motion i.e. no stopping.

Would I use two timing circuits? e.g. one to firstly energise the relay then the other to reset the original timing circuit? Does this work?

Sorry if the answer is easy but im lost!

 

[Nigel Goodwin]

You've already got the perfect solution - limit switches - a timing method won't be as accurate.

 

[Coded_Bananas]

The only thing with the microswitches is that i have to run 4ft of string between them to switch them. I was just thinking of whether I could neaten it up with a single enclosure, attach the enclosure to the wall and then thats it.

Thanks for the quick response!

 

[Tarsil]

How about two optical switces? That way don't need the string. U can make every switch from a LED&phototransistor.

 

[musthave]

do you whant it to stop at the same position every time

 

[Madhouse]

Could you not just use a read switch on the spider, and bury two magnets in the wall at the top and bottom of the path (perhaps painting over them or putting them the other side)? Simple, but may not be practical if you don't want to mark the wall in any way....

All you need to do then is reverse the direction each time the read-switch is activated (use some debouncing as well).

 

[Coded_Bananas]

Stopping at the same spot is not essential so long as I get a good up and down motion. I was trying to avoid having much on show. I suppose an even simpler method would be to just have a length of string the required drop length and one microswitch. The string would then unroll to the required length and then simply wind back up the other way. The microswitch would then reverse the motor.

God damn thats it! lol! Im gonna try that way! Everything could be housed in a simple small enclosure with only spider on show! Talking ideas through certainly helps! Thanks!