Scioly.org

Recently the motor that I used in conjunction with the photocell broke...it was a cooling fan from a laptop. Can the photocell only activate really small motors? (as in require a very small amount of voltage). What other motors have you used in the photocell step?

I'll get back to you on this one, but I'm experimenting with photoresistors today, in conjunction with motors.

I really hate how in the rules they said "photocell", as opposed to "photoresistor". Upon reading it, I immediately thought they meant "photovoltaic cell", as in "solar panel". Then I read later in a rules clarification that they really meant photoresistor. How annoying, I spent two weeks trying to make a photovoltaic cell work.

Anybody else have any ideas?

We have been having difficulty getting our photocell to even power the motor. If anyone has any advice, it would be much appreciated.

Hi Guys

Take a look here:
http://soinc.org/official_rules_clarif_2009

Basically: there was a rules clarification that basically states the light has to activate a switch (using a solar cells) that powers the motor. Meaning batteries can be used and this process becomes a lot easier than trying to power the motor with the light itself....

Hope this helps. If you check the Science Olympiad Wiki page you'll see that there's a picture of the circuit you'll more than likely want to use.

Sounds good...
Must you use a photovoltaic cell (as in solar cell), though?
Would it be legal to use a photoresistor instead?

I was thinking that one could use the photovoltaic cell to power a relay, and close another circuit. Legal?

Actually, you must use a photoresistor, turns out a while back they pulled a 180 and decided that photovoltaic cells such as solar cells are illegal =P

if you connect photocells to a relay you can power bigger motors as well

Everything in this thread has been covered in depth on the Photocell Bonus thread.....-
-what is and is not considered as a "photocell
-use of relays
-how to hook it all up and make it work.

Using a relay allows you to use pretty much whatever motor you want to. We're using a 12v computer cooling fan- (triggered by the photocell unit - )12v/20w bulb, photoresistor, 9v blue Radioshack relay) All powered by a 9.6v cordless drill battery. Works like a charm......
Box ran at 60.04 sec at Regionals yesterday.....

Balsa Man wrote:Everything in this thread has been covered in depth on the Photocell Bonus thread.....-
-what is and is not considered as a "photocell
-use of relays
-how to hook it all up and make it work.

Using a relay allows you to use pretty much whatever motor you want to. We're using a 12v computer cooling fan- (triggered by the photocell unit - )12v/20w bulb, photoresistor, 9v blue Radioshack relay) All powered by a 9.6v cordless drill battery. Works like a charm......
Box ran at 60.04 sec at Regionals yesterday.....

Wow 60.04 sec? that's incredible. did you medal?

htmlfreak wrote:did you medal?

Oh, yeah; 1st. The other box (our Team 1) was 4th with the touch. We'd have been 1st and second. Both boxes were running within a couple tenths over 60 on Friday night....