I need help fast!

R

rgg

New Member

• Jan 15, 2010

• #1

I'm working on a project where I need to use a photocell to activate a motor. What I've done so far is place a photocell, that I bought from Radio Shack, in line with a 9 volt battery and a small fan. Originally the fan ran off of two AA batteries, but it also runs fine if you hook up the 9 volt battery to it. My problem is the fan WILL NOT work once the photocell is plaqced in line. I've checked the p/c and it appears to work correctly. Does anyone have any simple ideas on what I could do to make the fan work with the photocell???

 

audioguru

Well-Known Member

Most Helpful Member

• Jan 16, 2010

• #2

Use a transistor. The photocell turns on the transistor with a low current that drives the fan with a high current.
The photocell uses a low current and the transistor amplifies the current.

 

R

rgg

New Member

• Jan 16, 2010

• #3

Thanks but i forgot to mention...

Transistors or not allowed for the project, any other suggestions?

 

J

Justin Barnett

New Member

• Jan 16, 2010

• #4

do you have to use a 9 volt battery? will it work with just 2 AA batterys

 

audioguru

Well-Known Member

Most Helpful Member

• Jan 16, 2010

• #5

A photocell uses a low current but a fan uses a much higher current. You must use a transistor between them.
If you are not allowed to use a transistor then use a logic-level Mosfet or a power opamp.

 

Mikebits

Well-Known Member

• Jan 17, 2010

• #6

Perhaps you should mention all the requirements and restraints of your project.

 

Sceadwian

Banned

• Jan 17, 2010

• #7

You can't use transistors? What kind of project is this where you can't use a transistor?

 

audioguru

Well-Known Member

Most Helpful Member

• Jan 17, 2010

• #8

Use bits of string and chewing gum like in the good old days.

 

Sceadwian

Banned

• Jan 17, 2010

• #9

hmm, do point contact diodes count? I see a plan coming together...