Hello, I saw this video, and wanted to know what kind of tranistor he uses, to switch the LED's on and off. It would be really helpful if someone could answer this. Thanks

 

http://www.youtube.com/watch?v=mLKPwWGBtIw

Sorry forgot to put the link....

 

It doesn't really matter what transistor he had as long as he had it biased for saturation. When a transistor is in saturation it acts more like an automatic switch. So you could use a standard 2N3904 or 2N2222 transistor to accomplish your goal. All you have to do is apply the appropriate resistor values to saturate it.

Austin

 

Hello,

It can also be any mosfet like IRF510 ( 10 volts gate) or IRL510 ( 5 volts gate).

Greetings,
Bertus

 

Yes inded, that would work too.

robotkid2945, I would advise you to research transistors a little more, particularly on saturation. We have a great AAC e-book that talks about this and I'm sure you can find more information from other sources. If you have any further questions you can simply post them on this thread.

Austin

 

One error he made though, 33 Hz is the minimum frequency you need before you can't see the flicker. This was established with TV sets.

 

One error he made though, 33 Hz is the minimum frequency you need before you can't see the flicker. This was established with TV sets.

Bill,
That was in the days of CRT TV's. The CRTs had their own "persistence of vision"; glowing phosphors.

You have to flash LEDs at a higher rate; they don't have the persistence that CRT's do.

 

Hmmm, I'm going to test that theory.

 

Hey Bill let me know the results of your tests, that's a very interesting theory to prove. It logically makes sense; anything below a certain frequency will appear to have flicker. Though that was with CRTs, wouldn't it be the same for anything? The eye still has a set frequency when it flicker is evident, but maybe everyone has a different set frequency? I'd test it on multiple people and see if they notice the slightest change in frequency.

Austin