Hello this is a copied thread from Modding...I figured I'd post it in here since it belongs here in the first place...the original thread with some comments from Zap and others can be found there. In the other thread, it was mentioned that this circuit and Zaps circuit are essentially the same...I'm not familiar with a darlington circuit...but if the second schematic above can be converted into a schematic that uses standard parts instead of IC's, kinda like zap's only uses transistors and stuff to do it...that would be awesome... I want one red LED to be lit when there's no HDD activity and the other red LED to be lit when there's no NIC Activity...I want them to each swap to a corresponding blue LED when activity occurs from their corresponding leads. Any help will be MUCH appreciated Sorry for copyign this thread around so much
All that the ULN2830A does is give you a simple package for 8 Darlington transistors. Like a buffer, kind of, but with a lot of current gain. Let's forget current gain though, because we're really switching here, not amplifying. The theory of operation is the same between macro's and ZW's implementation. I'll explain that, and hopefully it will become clear how you can implement this to suit your needs. The HDD activity header is active low, and so there's a pin that's at +5V, and one that's LOW to indicate the activity. This is really being generated by the IDE electronics, it's on pin 39 of the cable, and passed through to the mobo header. Anyway, the optoisolator (or one of ZW's transistors) will have a current flowing in the collector during HDD activity. ZW's design is probably more adaptable to what you need--he just uses a complementary pair of transistors (as I recall, he has a 2N3906 and a 2N2222--not exactly the complementary matched pair in the strict sense, but one PNP and one NPN respectively). Macro uses a pull-up to invert the sense of the signal. In the PNP transistor, the base current flowing causes the collector current to switch OFF, and in the NPN, the base current flowing switches the collector current ON. So in general, use one complementary pair of transistors (2N3904 is the complement to 2N3906, and should be very cheap, I paid $0.06 for mine). Tie both of their bases back to the signal you are trying to use for a switch, and put LEDs in the collector circuit. Lather, rinse, repeat. The optoisolator is pretty much optional, but I'd do a lot more testing if you choose to omit it, making sure your rig doesn't have shorts that will fry your IDE electronics.
I understood very little of what you said. I am at the point where if you give me the parts and a schematic, I can build it...and I know a few simple electronic calculations and what not...but stuff liek this I am still learning...I basically understand, but kinda don't in a way ya know? What I'm needing now is a schematic diagram and (american) parts list that will do both NIC and HDD.I'm not sure if the NIC is the same as the HDD with the negative being the switcher...I don't have a multimeter yet to test it (there's one at work) and wouldn't know what to be testign for anyways... And yes, I'd DEFINITELY want to go with the opto-isolator just because I'm not certain of what all this does. cpemma also posted a circuit in the articles forum under the HDD light thread...I REALLY like that circuit...and I'm only missing one thing, and thats whether or not I can use a GES-5307 darlington transistor or do I need a different one...if you coudl go look at that and give me some feedback on which one I need, I'll be done with this and stop being a bother Thanx for the replies tho! Do ya'll have a chatroom ya'll hang out at anywhere?
