Tech Directions - December 2007 - (Page 16)

Op-Amp Checker Fig. 3—Front panel drawing PTT OP-AMP —Vs +Vs ing. Left LED flat side up and right LED flat side down. Bend and solder the leads of the right LED to the left LED. 11. Using the wiring diagram (Fig. 4) as a guide, carefully solder the various components to the 8-pin DIP socket, the PTT switch, and LEDs. Per Figs. 1 and 4, solder the two battery clips into the circuit. The opamp checker’s hookup connections should resemble the unit shown in Photo 3. 12. While the op-amp checker is using a #54 drill bit. Do not insert the 8-pin socket at this time. 7. Determine the location of the PTT push-button switch. Mark the spot to be drilled with a pencil, and drill the hole using a #J drill bit. 8. Find the locations where the four mounting screws will be inserted through the perfboard and attach to the plastic enclosure. Mark each spot with a pencil. Doublecheck the measurements, and, if all is OK, drill the holes using a #30 drill bit. 9. Per the front panel drawing (Fig. 3), press the 8-pin socket into the perfboard. It should fit snugly. Make sure that the indent on the 8-pin socket is at the left. Mount the push-button switch to the panel. Do not tighten the hex nut at this time. Just snug it down. 10. Referring to Fig. 3, insert the two LEDs. Viewing from the outside of the panel, make sure the flat sides of the LEDs (cathodes) are oppos- R LED L LED 220 Ω 5 6 7 8 S1 22 K 220 K 2.2 K 4 3 2 1 .1 μF Red Blk — + + — Red Blk Fig. 4—Wiring diagram Photo 3— Hookup connections still apart, attach two 9 V batteries to the battery clips. Insert an opamp into the test socket and press the PTT switch. If it works—great! If not, determine what the problem is and fix it. Insure that no soldered wires or component leads touch other points. If necessary, refer to the proto-board circuit that is still intact. 13. Once you have satisfied yourself that everything works properly, tighten the PTT switch’s hex nut. Carefully place the attached batteries in the plastic box. Both batteries should be on their narrow sides. Put a piece of sponge between the bat 16 techdirections ◆ DECEMBER 2007

Table of Contents Feed for the Digital Edition of Tech Directions - December 2007

Tech Directions - December 2007 Technically Speaking Contents Direct from Washington The News Report Technology Today Technology's Past Mastering Computers Is This Op-Amp Any Good? Lab-Built Checker Removes All Doubt Here Comes the Sun! Residential Solar Systems Add Up to Savings Pinhole Cameras—For Science, Art, and Fun! Poster Project Maps Out Design Process Gifts for Geeks E-gallery More than Fun

Tech Directions - December 2007

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