Digtal output

lol goos circuit

netking, if you want to learn more about electronics, go through the tutorial attached to this program, what you are posting is just graffiti, and is not of much use.

Thats got to be the 15th time you've said that to someone, I agree, but at least he's not posting the stupid insulting shit over and over like some of these new idiots... Why not just explain why you say that, and perhaps he will learn from it and take your advice, only one way to find out!

@Issacsutt, I am finding too much wrong with these circuits to suggest corrections, if you can offer different help, please do so rather than having a crack at me for not doing so.

I'm not trying to crack you, I think your very knowledgeable about electronics, and just thought they would learn better from what you could say, rather than from the tutorials. But, those other idiots will never learn, so it would be a complete waste of your time to say anything to them, however I felt like others such as @netking might be more willing to listen.

I understand BillyT. Issacsutt go and help netking, lets see. I think help is in this caase impossible since the basics are not there.

Well personally, if I were trying to make a logic probe, I wouldn't have used an OP AMP for starters, I would've just used a transistor... but not without a voltage divider to establish some threshold of around 2.5V to differentiate between High and Low, because a Low digital signal could have some leakage, or a voltage drop caused by the pn junction in a transistor that could falsely trigger the probe's transistor to conduct, thus falsely turning on the LED. Secondly, I would probably use two LEDs instead of just one that would only come on when High, and turn off when Low, because if there happens to be no signal on the node your testing by mistake, you wouldn't be able to tell; the LED could be off representing a LOW or off because there's no signal... you wouldn't know, so it would be a better idea to represent High with one LED, and Low with another... which means that you would need either a PNP and an NPN transistor, or an NPN transistor and an inverter. Finally, you might want include some kind of protection circuit, cause what if the point your testing some how has higher than a nominal 5V accrost it, you wouldn't want it to get damaged, a voltage regulator built from a moderately high value resistor in series with a zener diode biasing a transistor, with maybe even a current limiting resistor, could protect it for what you need. An OP AMP could be used if you really wanted, to control the threshold input more accurately, but bipolar transistors should work nearly just as well for this. Considering netking's circuit though, the OP AMP is a complete waste, doing nothing more than passing the signal here, and the circuit serves more as a flashlight than it does for "testing a digital input" like a logic probe.

Issacsutt, that was a good commentary of the thought processes when designing a logic probe, the only problem with it is that even I had to sit back and analysis each stage as I read it, I wonder if netking will be able to grasp the intricacies.

Ok I see what you mean, thanks. So far not nothing from netking ...though he did join just yesterday

Yeah, probably just a trial person, I'm not trying to be mean, I'm just trying to let these trial people know that electronics is not just about throwing a handful of components together and calling it a circuit.

Yeah exactly!