Arghh...

ajward

Taking a break from Bob and Ted, I've been diddling with the PIR sensor. Built an NPN transistor circuit the PIR could use to control a relay that would switch on a video camera and recorder.
An hour an' a half and I couldn't get the 'switch' to work. :frown:
It was then I had a "Doh!" moment.
NPN and PNP transistors from the same manufacturer can look exactly alike!

Moving right along....

Amanda

Kevin Wood

Yeah, you gotta look at the arrows.

kwinn

Kevin Wood wrote: »

Yeah, you gotta look at the arrows.

Or the part number!

HollyMinkowski

They all look alike to me.

I was building some small circuits using pnp and npn's in TO-92
packages and kept mixing them up. I finally put little red dots on
top of the npn's in my parts case using nail polish :-)

wjsteele

Ah... your voltage simply wasn't high enough. Crank that baby up and it'll work... if ever so briefly! :-)

By the way... the nail polish trick is a good one... but I use a red sharpie... it still looks a little funny when a guy goes into a drug store to buy red nail polish.

Bill

HollyMinkowski

wjsteele wrote: »

By the way... the nail polish trick is a good one... but I use a red sharpie... it still looks a little funny when a guy goes into a drug store to buy red nail polish.

Hey, this is the new millennium....you could even get away with wearing the polish ;-)

schill

Instead of nail polish, I used to use small dots of Testors enamel model paint.

ajward

@Holly All I have right now is clear polish and I can see a problem there!