what is logic tester and wht principle does it work?theory for logic tester?

Answer 1

The previous post would be good if this question was under philosophy since there are logic classes in philosophy. Since you asked this question under the Engineering topic, I assume you mean an instrument used in electronics for testing logic circuits.

Logic circuits in electronics use simple voltage levels to indicate "On" and "Off" or "1" and "0" binary conditions. There are logic gates that implement logic functions such as AND and OR and the logic tester instrument allows the pins of the logic chip to be probed to verify things are working correctly. They typically have an LED or light on them that lights for a 1 and a different color or position that lights for a 0. Some of them may have audible tones for each condition and many of them have more advanced features such as an indication of a "clock" (signal that is rapidly changing between 1 and 0). There are different types of logic chips which use different voltage levels to represent the 1 and 0 states, so good logic testers allow all of these standard logic families to be tested (TTL, CMOS, ECL are the big three families).

These work by using a battery powered circuit to referenced to a ground point on the circuit under test to buffer the monitored signal, then to drive an LED. Pulsed detection is more complicated, but uses transistors or logic gates which act to detect the pulsing condition.

Having said all of this, most engineers do not bother with logic testers anymore. For one thing, most good digital multimeters (DMMs) can be used to probe logic circuits to see if they are pulsing or if they are at a voltage level typical of a "1" or "0". The second reason why is that many of the circuits to be tested now have large busses and we tend to use logic analyzers more often for this. These devices allow 10's to 100's of signals to be monitored simultaneously with the results captured on a graphic screen. Many are PC based and will store a sequence of pulses and allow combining several of the signals being monitored into a bus. They can display the bus as it changes in binary, hexadecimal, octal, decimal, and ASCII in a list form and in a graphic form. They are pretty handy devices for testing digital and microprocessor based systems.

Hope this answer has helped you!!

Answer 2

Well, logic is a theory. Logic tester would be the theory that implies that logic is about, or logic is or is not present within the terms of context to the logic (because we believe this or that is logical, may not be logical at all, so it depends on the context, or the environment and the people.) I would say the crux, or essence of logic tester (if I have understood you correctly), would be the pointing our of falacies or inconsistences within, or about the logic presented. I believe the point of logic is to point out holes in an argument; even this argument has holes in it though, so, this may also imply that we are on the wrong kind of logic all together, thus this "logic tester" you speak of, would be a completely useless notion that would not add up to the kind of logic some might say we "should" be looking for or using.