Electronics Chaser LED's, resisters and all things in between

"bump bump bump... yeah! u cant touch this!" linear? can u confirm this so i can start buying the parts?

Thanks
David

 

Er, I can't really make it out from the pics.

How are the LEDs connected? it's either between the chip and +V or the chip and ground.

 

the negative side of the leds connects to the chip. and it *looks* like the 12v runs though the chip then out to the battery. But on the way it stops a lot (R's and C's) on the board.

David

 

Do i need to explain it another way? Do u understand it?

David

 

I understand.

But it's your device we're modifying here. I'm not gonna start spouting part numbers and whatnot until we know what's up. With the meter, that's a known chip, so I'm comfortable with modifying that. On the scanner, you'll either use NPN transistors if your driver is active-high, or PNP transistors if it's active-low like the 3914 is. Fundamentally, that's the only thing we need to know, and there are only two cases. 2N390x will only cost you 6 cents apeice, so it's not like it's a huge expensive purchase anyhow, shipping will be the biggest part of it probably.

I'd sure start by connecting one of your outputs to a transistor and checking it out. Make sure to remove the LED though.

 

linear got another q 4 ya

I went by radioshack to pick up some resisters (180) but i did not see any... the highest i saw was 80 or so? am i looking at the right thing?? because i cant even find one online rated at 180....

Thanks,
David

 

Re: linear got another q 4 ya

It's a standard E12 value, everybody (except R@Shack) sells them.

 

So is it a good idea to get the transisters @ radioshack or online as with the resisters???


David

 

cpemma,
Can u give me links to sites that sale them? Both resisters and transisters at the same place would be nice so i can just buy it from one place. Thanks

David

 

Hey

Well i finally got everything i needed (the 180 resisters and pnp & npn transisters.) I hooked the 8 LEDs with 2 resisters (1 for every 4 leds) and a pnp transister. They all work when i suply 12v to them but when i solder the transister to one pin of the chip, it still stays on when its suppost to go off. Am i doing somthing wrong? I have it set up as follors:

Code:

                 12v [E]
                    |
Pin on chip[B] -----[O]C---- /\/\/----[]--[]---[]--[]---Ground
                         |---/\/\/----[]--[]---[]---[]---|

Should i go ahead and the NPN? I didnt want to because i didnt want to fry it. Also, the PNP isnt labled like the PNP one is [E|B|C]
Any fast help would be great becuase i need to get this finished by tomorrow.

Thanks for your time,
David

 

Re: Hey

So what transistor code number is it? A google on the part number will give you the pin connections.

 

the NPN is:
2N
3306 (3904??)
724

the PNP is:
F2N
3906
EBC

hope this is what u asked about.

 

According to one of the very few references, a 2N3306 is a PNP transistor.

 

2N3306 doesn't sound right to me.

My multimeter has a little feature to sniff out what kind of transistor you have and the pinout, but I doubt that helps you very much.

2N3904 is readily available, say at Radio S*ack. It's the complement to 2N3906.

http://www.fairchildsemi.com/ds/2N/2N3904.pdf
http://www.fairchildsemi.com/ds/2N/2N3906.pdf

Diagrams for the pinouts can be found on the respective first pages of the datasheets.

 

Hey Liner/cpemma,
I tryed hooking the NPN up like the PNP (like the PDF for it said) and none of the LEDs on the line worked.

Am i hooking them up wrong? I have the soldered to the pin on the Varad Chip thats going to LED1. The [E] going to a 12V power. The [C] going to a resister (180) out to 4 LED's and then the end connected to a ground. Then a second resister connecting 4 more LEDs and is also grounded.

When i am using the PNP, they all light up just fine. But they dont blink on/off when its the LED1's turn to light on and off (for the scanner effect). If i just have the 12v [E] and the [C] hooked up they still are all on without being saldered on to the pin on the chip.

As far as i can tell by magnifiging glass, the transister says 3304 on it. I know of the 3 and the 0 4 for sure.

Please get back with me on this, its driving me crazy. If i need to get some more resisters then i hope i can get them at radioshack cuz i need to get this finished by sunday.

Thanks for your time,
David

 

For the PNP, the emitter (E) goes to +12v, but for a NPN, E goes to ground. The arrow symbol points towards ground in each case.

If the leds light without the base being connected, sounds like the transistor is broken.

 

Well i have tried it both ways.. still doesnt work at all on the NPN side. I have 30 PNP transisters and i have used about 5 of them, all light up without being connected to the base, yes. But still do not work at all.

Need more light shedded on this one guys. I'm lost.

David

 

ok, i STILL need help with this project. Any ideas or drawings of how this needs to be put together would help.. i have tryed all i know to do and was told.... what else do i need to do???


David

 

Connect a NPN transistor (2N3904).

Connect BASE to your 3914.

Connect COLLECTOR to 12V.

Connect EMITTER to positive side of one LED, and hook up 3 more LEDS the same way in series (negative/flat side going away from the transistor). Put the resistor at the end going to ground. Test it out.

This would have been much easier if you had a volt meter. That way you could measure the voltage coming from the output when it was supposed to be on.

From the sounds of it, if you hook-up the PNP and its always on, it sounds like your output is active high, but output voltage is lower than 12V. In other words, if your outputs supply 5V, and your sourcing your transistor to 12V, it would constanty be a low signal for the PNP, and thus stay on all of the time.


PS: on second thought, go get a multimeter or something and measure the voltage coming from the outputs. If the flashing sequence is too fast, you may not get an accurate reading unless you use an osciliscope.

 

HAZER,
I will go out and buy one today. I really would like to get this thing working cuz i have 280 LED's just waiting on me I will get back with you.

David