Electronics Forum

by **Tom44** » Thu Dec 11, 2014 4:35 pm

Hello. I am currently working on a circuit for a project I have created.
I need help with creating my circuit. I want the circuit to rotate an object for 10 seconds whilst four LEDs are on for 10 seconds too. I want the circuit to be activated by a LDR and a button. The LDR will be placed in a surface where a ball will roll cross so once the ball has crossed I want the object to rotate and LEDs to turn on.
Thank you in advance and if you have any questions please ask.

by **KMoffett** » Fri Dec 12, 2014 3:26 pm

Do you have any spec's, voltage and current, on the motor you will use for the rotation? Is the start and end position of the rotated object important, or just 10 seconds of rotation? Is the purpose of the "button" to start the rotation in lieu of the LDR circuit doing it?

Ken

by **Tom44** » Sun Dec 14, 2014 10:06 am

The motors' voltage rating is 1.5V to 4.5V and the max current is 1.17A. The start and end position of the rotated object are not important. I want the button and LDR to both trigger the object to rotate and LEDs to turn on for 10 seconds.

Tom

by **KMoffett** » Mon Dec 15, 2014 1:22 am

OK, an LM555 10-second monostable driving a N-MOSFET, that switches on and off the motor and LEDs.
What power source? Battery, wall wart, ...?
What LEDs. Different LEDs have different minimum voltage requirements and maximum current ratings.
What LDR, and what light source will illuminate the LDR.

Ken

by **Tom44** » Mon Dec 15, 2014 9:16 am

It will be powered with a battery on a battery snap. The LED is the standard 5mm. Above the LDR there will be an LED that will always be on.

Tom

by **KMoffett** » Mon Dec 15, 2014 3:20 pm

When someone says "battery snap" I assume they mean a PP2 9V battery. Is that what you're intending to use? 5mm is a physical dimension. Bur, it sort of implies a ~10mA LED current. What color do you intend for the 4x LEDs and for the LDR LED? That determines the LED voltage rating. How far from the LDR is the LED?

In my design job I tend to ask a lot of questions of my customers. Often the answer is "I don't know"... and that's a helpful answer too.

Ken

by **Tom44** » Tue Dec 16, 2014 9:06 pm

The battery is a standard 9V. The colour of all the LEDs are red and the LED above the LDR is about 1cm.

Tom

by **KMoffett** » Fri Dec 19, 2014 4:51 pm

[quote="Tom44"]The battery is a standard 9V. The colour of all the LEDs are red and the LED above the LDR is about 1cm.

Tom[/quote]
"...motors' voltage rating is 1.5V to 4.5V and the max current is 1.17A."
A 9V PP2 battery will not last long with that motor...like minutes...maybe. I would go with three AA-cell. C-cell or D-cell batteries, depending on your size limitations. Is that possible?

Ken

by **Tom44** » Fri Dec 19, 2014 7:16 pm

Yes, I can get three AA-cell batteries. Could you direct me to a website that sells them?

Tom

by **KMoffett** » Fri Dec 19, 2014 7:48 pm

Tom,

I'm have my doubts about your ability the locate the necessary timer circuit parts if you don't know where to get AA ("double A") batteries. These are generally available in any store everywhere in the world. Where are you?

Ken

by **Tom44** » Sat Dec 20, 2014 6:21 pm

England

by **KMoffett** » Sun Dec 21, 2014 12:07 am

These are images AA batteries: [url]http://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0CAcQjRw&url=http%3A%2F%2Fpixgood.com%2Fduracell-aa-batteries.html&ei=xgyWVODoKtOWyAT724KwAw&bvm=bv.82001339,d.aWw&psig=AFQjCNFsBNE5RxRXm5g5SF6xm4tCkwqRsw&ust=1419206200231819[/url]

You should be able to get them at any grocery/hardware/electronics/chemist..shop.

I don't know if there are any electronics parts stores in you local area, like Radio Shack here, so before I start up a design project, can you let me know where you will get the electronic parts.

Here are online resources in the UK that I know about:

[url]http://uk.farnell.com/[/url]

[url]http://uk.rs-online.com/web/?cm_mmc=UK-PPC-0914-_-google-_-0_RS_Components_Longtail-_-UK_Only_rs+uk_E&gclid=CPDnhM7o1cICFQ9gMgodi2UAUw[/url]

[url]http://www.maplin.co.uk/[/url]

Ken

by **pebe** » Sun Dec 21, 2014 5:45 am

Or here is the one I use. Fast delivery and very reasonable cost.

http://www.bitsbox.co.uk/

by **Tom44** » Sun Dec 21, 2014 10:27 am

I already have plenty of electronic parts.

Tom

by **KMoffett** » Sun Dec 21, 2014 7:53 pm

OK, here is a circuit that should work for you. I have not bench tested it, as I don't know the specs on the LRD/LED sensor you may choose or how much current the motor will draw under you load.
Ken