Total solder points: 47 Difficulty level: beginner 1 2 3 4 5 advanced METAL DETECTOR K7102 drilling s when r te s a is “Avoid d les in walls...
Features & Specifications To come up against an electric cable while drilling a hole in a wall can have catastrophic consequences. Likewise, drilling into gas, water pipes or central heating pipes can be extremely hazardous. With a handy metal detector it can now be determined beforehand whether there are metal objects to be found in a wall, ceiling or floor. An LED indicates if a metal object is in the vicinity.
Assembly hints 1. Assembly (Skipping this can lead to troubles ! ) Ok, so we have your attention. These hints will help you to make this project successful. Read them carefully. 1.1 Make sure you have the right tools: • A good quality soldering iron (25-40W) with a small tip. • Wipe it often on a wet sponge or cloth, to keep it clean; then apply solder to the tip, to give it a wet look. This is called ‘thinning’and will protect the tip, and enables you to make good connections.
Assembly hints 1.
Construction 2. Diode. Watch the polarity ! 1. Coils The coil consists of two windings around the ferrite core supplied. D1 : 1N4148 CATHODE D... In order to facilitate winding, thin double sided sticky tape can be stuck to the ferrite core, each winding can be held down using ordinary sellotape. 3. Zenerdiode. Watch the polarity ! Both windings must be wound in the same direction (see fig 1.
Construction & connection 4. Resistors 6. Transistors. R... R1 : 330 R2 : 470 R3 : 470 R4 : 2K7 R5 : 10K (3 - 3 - 1 - B) (4 - 7 - 1 - B) (4 - 7 - 1 - B) (2 - 7 - 2 - B) (1 - 0 - 3 - B) T1 : BC547B T2 : BC547B T3 : BC547B 8. Trim potentiometers RV1 : 2K5 RV2 : 100 7. LED. Watch the polarity! LD1 : 5mm RED 9. Push button 5. Capacitors. C... LD1 Choose C1 : C1 : 1n2 C1 : 3n3 SW1 (122) (332) Experiment for best result.
Assembly 10. Assembly Connect the battery terminal to the point marked “+” (red) and “-” (black), see figure 2.0. Black Fig. 2.0 Red Connect the windings to their respective points marked with a, b, (L1) and c, d (L2), see figure 3.0. Fig. 3.
Test 11. Test & final adjustments 1. 2. 3. 4. 5. 6. Connect a 9V battery to the battery holder. Go to a place where NO metal object is known to be in the vicinity. Turn preset RV1 fully clockwise. Turn RV2 fully anti-clockwise. Depress the push button and hold it in during the final adjustments. Turn RV1 anti-clockwise until the LED goes out. All further remaining adjustments are now concerned with RV2 only. To set to maximum sensitivity: turn RV2 until the LED is weakly lit.
Drill pattern 12.
PCB 13. PCB layout.
Diagram 14.
VELLEMAN Components NV Legen Heirweg 33 9890 Gavere Belgium Europe www.velleman.be www.velleman-kit.com Modifications and typographical errors reserved © Velleman Components nv. H7102IP - 2004 - ED1 (rev.1.
