Complete noob help. Switch to turn on motor and turn off by itself.

[guyandho]

I am a complete newbie at electronics. So please bear with me.

I would like to create a switch that will turn on a small motor (only needs 1.5-3V DC). I would like to turn on this motor, and after it runs for a certain time, or after something moves for a certain distance, the motor will turn off, or the switch will turn off.

Does anyone have ideas on how to do this?

Basically, the motor will be attached to a pulley, which will pull open a tiny curtain to a picture frame. I am doing this as a Christmas present.

Thank you for any advice you have.

 

[jgharston]

Basically, the motor will be attached to a pulley, which will pull open a tiny curtain to a picture frame.

You could have a switch that detects when the curtain is open and use that to turn off the motor.

 

[DerStrom8]

I am a complete newbie at electronics. So please bear with me.

I would like to create a switch that will turn on a small motor (only needs 1.5-3V DC). I would like to turn on this motor, and after it runs for a certain time, or after something moves for a certain distance, the motor will turn off, or the switch will turn off.

Does anyone have ideas on how to do this?

Basically, the motor will be attached to a pulley, which will pull open a tiny curtain to a picture frame. I am doing this as a Christmas present.

Thank you for any advice you have.

Welcome to Electro-tech-online, guyandho!
This could easily be done with a 555 timer wired in monostable mode. You press a momentary push-button switch, it turns on the output for a set amount of time (determined by a variable resistor) and then shuts off. Here is the basic schematic for this circuit:

**broken link removed**

You will probably want to connect a transistor to pin 3 of the 555, as the 555 probably won't be able to source enough current for the motor. You can probably run the whole thing on two AA batteries, though this is quite low for the 555 timer supply voltage. I would recommend using at least 3 AAs (4.5 volts) which shouldn't damage the motor.
Hope this helps, and keep posting!
Der Strom

NOTE: The unlabeled resistor and capacitor determine the length of the output pulse. I would use, say, a 1uF capacitor and a variable resistor so that the pulse length is adjustable. You could also experiment with capacitors and fixed resistor values until you get it to stay on for the amount of time you need. Good luck!

 

[ronv]

I bet you want to both open and close the curtain. If so you can use a DPDT switch with switches at both ends - Or, if everything is sturdy enough you could use a DPDT center off switch and let the motor stall at the ends.

 

[guyandho]

Thank you all for your replies. I will try it out. I will look into the DPDT switch first. Is the 555 kind of like a controller? I think I might incorporate the DPDT into the 555 so that I can open and close the curtain as well, but it has to go only a certain distance though. Is this possible? Or will the 555 achieve this w/o the DPDT?

When I have tested it out, I will post results.

And look forward to more post. I am very interested in electronics. I want to create a DIY car started this winter, hopefully before the snow melts so I can use it. lol.

Thnx guys..... and gals.

and P.S. I am not a sexist. My name is Guy Ho. Hence the username guyandho, just thought it's a little funny is all (since I've been made fun of before).... just fyi

 

[BrownOut]

What you need are limit switches that stop the mechanism at the desired position. I have a schematic at home of such a system, will post later...

 

[BrownOut]

Couldn't find the drawing I promised. But take a look at this thread.

 

[DerStrom8]

The 555 is a timer. In the monostable (or one-shot) mode, it is set to turn on the output for a certain amount of time when a momentary push-button switch is pressed (output turns the motor on) and then shut it off (which turns the motor off). Another idea would be to use a 556 instead (a double 555) and control two different motors--one to lift the curtain, the other to lower it. This way you could use the DPDT to tell it which [internal] 555 to turn on. If you want, I can put together a schematic for you.
Der Strom

 

[ash20]

This could easily be done with a 555 timer wired in monostable mode!

this is the best way i think.. i was going to suggest it myself..

 

[ash20]

i am not sure whether this is a good idea but you can use a photodiode for this.. when it detects any light, it passes current proportional to the amount of light...

(A photodiode is a type of photodetector capable of converting light into either current or voltage, depending upon the mode of operation)

...so when you enter the room with lights open, it will detect the light and pass the current, which will drive the motor and then the curtains will open ... ummm do you like this idea??? :-|

 

[DerStrom8]

i am not sure whether this is a good idea but you can use a photodiode for this.. when it detects any light, it passes current proportional to the amount of light...

(A photodiode is a type of photodetector capable of converting light into either current or voltage, depending upon the mode of operation)

...so when you enter the room with lights open, it will detect the light and pass the current, which will drive the motor and then the curtains will open ... ummm do you like this idea??? :-|

There's just one thing wrong with it: The curtain that the original poster is talking about is a tiny one on a picture frame

 

[ash20]

The curtain that the original poster is talking about is a tiny one on a picture frame

well then how much help will 555 do?? its more bulky for a picture frame... it would be much better if original poster simply connects a long wire to the motor and then when he wants to show to someone, he could just pick the wire(with switch) , press the switch and his work is over.. the circuitary will make his idea a little bulky!!

 

[DerStrom8]

Just a quick question for guyandho:
In your original post you mentioned that you wanted the motor to turn on and off by itself. Would it work instead if you used a SPTT with the center position being off and either of the two other positions being momentary? This way you would have to HOLD the switch in the "up" or "down" position to make the curtain go up or down, but it would be much easier to make. What is your preference?
Der Strom

 

[DerStrom8]

well then how much help will 555 do?? its more bulky for a picture frame... it would be much better if original poster simply connects a long wire to the motor and then when he wants to show to someone, he could just pick the wire(with switch) , press the switch and his work is over.. the circuitary will make his idea a little bulky!!

The 555 circuitry is very compact. The whole thing (excluding the motors) could fit on a board, say, 3x5cm. and be no thicker than a few millimeters.
I may have misunderstood your previous post. I was thinking that you were talking about opening window curtains (full size), so I apologize for the misunderstanding
I believe guyandho was hoping to touch a button once and the circuit would do the rest of the work. If he simply uses a switch, as you suggested, he would have to hold it down (if it's a momentary switch) or else turn it off when the curtain has fully opened or closed. With a 555/556, all he would have to do is press a momentary switch once, let go, and the curtain would open or close all the way by itself.
Der Strom

 

[guyandho]

DerStrom, your idea about the SPTT with the momentary switch sounds like something I would look into. Work for the weekend! awesome!

But I got another idea, from Ash20. I was thinking of using a motion sensor to activate the motor. One idea is to use a cheap photoelectric sensor with a laser, and when the laser is trip, the sensor will activate the motor, which in turn will be controlled and timed by the 556. Is this possible? How much do motion sensor cost? or photoelectric sensor? Which is the cheapest way?

What do you guys think?

 

[DerStrom8]

DerStrom, your idea about the SPTT with the momentary switch sounds like something I would look into. Work for the weekend! awesome!

But I got another idea, from Ash20. I was thinking of using a motion sensor to activate the motor. One idea is to use a cheap photoelectric sensor with a laser, and when the laser is trip, the sensor will activate the motor, which in turn will be controlled and timed by the 556. Is this possible? How much do motion sensor cost? or photoelectric sensor? Which is the cheapest way?

What do you guys think?

You may be able to use a simple motion sensor using a two CdS photocells and two 393 comparators (the output is tripped when even a very slight shadow is cast over the sensor), ad the outputs of the 393s would trigger the corresponding 555s. There is also a dual 393-- the LM339--which you could use together with the 556 to achieve this. This way, there would be one sensor to lift the curtain, and one to close it. All you would need to do is wave your hand over the desired photocell.
Der Strom

 

[guyandho]

Guys bad news. First off, I want to thank for all your your responses. But I have to postpone this project for the time being. My father is in the ICU for a heart condition, and I have to take care of him for now. The present/project will have to be worked on later. I might just buy something for him yet.

Thanks for all your response though, and I will get to back to posting soon. And maybe on the project too when everything is back to normal again.

 

[DerStrom8]

I am very sorry to hear that your father is unwell. Give him my best, and good luck to the both of you. I hope he gets better soon :/
Sincerely,
Der Strom

 

[ash20]

may god make him well soon.. good luck to both of you....