Logic Probe For Ttl Circuits

THE LOGIC PROBE
The Logic Probe is an economical and useful device for testing a logic circuit. It displays the HIGH and LOW with different coloured LEDs. The purpose of a logic probe is to examinethe logic states at a particular point in an electronic circuit. It is usually used in fault finding and testing but it can also be used to find out how a piece of electronic equipment works or toassist in electronic design. This probe effectively functions as a logic-level indicator for TTL circuits.

PLACING AND SOLDERING PROCESS
Flux is used before soldering process to clean surface of theboard. The main function of flux is to clean and remove any oxide from the board and from components. These oxides deposited on the board may not permit good solder joints. If the solder joint ispoor, there will be poor electrical conduction or poor flow of electricity through the circuit.
Solder flux helps to de-oxidize metals (copper tracks on the board and leads of electronic components) andhelps better soldering and wetting. The activators in the flux promote wetting of the molten solder to the surface mount lands and component terminations or leads by removing oxides and other surfacecontaminants.
After the soldering process is over, it is important to clean the board to remove any unwanted residue that can affect the performance of the board and can even cause electrical shortcircuit. No-clean flux does not need any cleaning.

Too much heat can make the copper trace lift right off the board substrate, then we will use a soldering pencil rated at 15-25 watts, no more.
Weinsert the wire or component leads into the board from the rear, and bend them over enough to keep the component from falling out.
We lightly touch the tinned pencil to the copper trace and the leadat the same instant. A couple of seconds later, we touch the lead with the end of the solder, adding just enough solder to make a puddle, but not enough to make a fat blister. The solder needs to...