Banana plug

Another test that I have found always brings out the inherent weaknesses of the part is the hard dV/dt test. Basically, I simply slam the red banana plug into the already-powered-up DC bench power supply and look for overshoots (voltage or current) in the switcher. There is a fair amount of natural input bounce created by this rather unofficial test, but that can really help aggravate/expose any startup logic issues with the IC. Of course we may later decide to specify a smooth (non-jittery) input AVI At for the IC and just move on. My colleague used to use a mercury switch for the same purpose. That gives almost the same hard input AV At, but without all the bounce. 

Multimeters have sockets into which test leads are inserted. Test leads are insulated wires that have banana plugs on one end, for insertion into the sockets, and metal tips on the other end, for contacting the points in the circuit that are being measured. 

Obtain a socket board and multimeter with test leads from your instructor. If not already done, insert the banana plugs on the one end of the test leads into the sockets on the multimeter for volt and ohm measurement. 

Place a gel, loaded with samples, on a block of reusable ice between two reservoirs containing electrode buffer. Connect the reservoirs to the power supply using electrical leads fitted with male banana plugs. Be sure that the entire bottom of the gel mold is in contact with the ice so that cooling is even. Orient the gel so that the wicks are closest to the negative pole (black or cathode). Use cellulose sponges or Handiwipes (available in most gro-... 

Two Petri dishes, insulated copper wire, banana plugs, alligator clips, glass plate, polished nickel-plated sheet iron (about 10 x 15 cm) as support, source of DC current (lOV), hair dryer, spatula, measuring cylinder, dropping pipettes, safety glasses, protective gloves. 

I) The white filter paper is impregnated with the NaCl solution to which have been added a few drops of the indicator bromothymol blue and a few milliliters of ethanol, dried almost completely with the hair dryer and placed on the glass plate. The DC current source (lOV) is brought into contact with the paper by means of alligator clips, copper wire and banana plugs in such a way that the poles are about 1 cm apart. The paper, which is colored yellow by the indicator, turns deep blue in the neighbourhood of the cathode. 

Solder a tungsten wire onto a banana plug. Sharpen the end of the wire by dipping it in a 3-M NaOH bath connected to a 6-V lantern battery. Attach the banana socket fused to the platinum plate onto a 150-mm petri dish with plasticine. Make a hole on side of lid of a 60-mm petri dish, insert the platinum plate through... 

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