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Metal Detector Kit + Project Case (HCKITS0028) 
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Joined: Sun Aug 05, 2012 4:02 pm
Posts: 632
Post Metal Detector Kit + Project Case (HCKITS0028)


With this kit of parts (HCKITS0028) you can build your very own metal detector capable of detecting hidden metal objects up to a maximum of 4cm away (depending on object). Using just through-hole components this is an excellent kit if you are not very experienced at soldering and are looking for a fun electronics project to practice with. The kit includes all the required components. All you will need to complete this project is a soldering iron, solder, a pair of cutters, and a power supply source or two AA batteries. We have also included with this kit an ABS plastic project case which you can optionally house your completed project (board will need to be attached with hot glue or tape).

How to build:

Soldering tip: When soldering components to a circuit board it is always best to start with the smallest components first. This helps keep the board flat and stops access to pads from being restricted by larger components. When soldering the through-hole components in this kit you should always apply the solder to the pads on the non-component side. When the component is inserted splay the components legs slightly. This will help hold the component in place whilst you turn the board over to solder. After soldering clip the excess component legs so that they cannot short circuit with other components.

There are 4 wire-ended resistors in the kit. These all have different values and can be identified by the different coloured bands on the resistor body as follows:

RED, RED, YEL = 220K

Reference the above image for correct placement. Their orientation is not important.

Ceramic capacitors:
These are small beige/brown circular disks with the value 104 printed on them. Solder these to the pads marked 104 as per above image. Their orientation is not important.

These are black components with 3 legs. There are 5 in total and have different values engraved on them as follows:

1x 9013
2x 9015
1x 9012
1x 9018

These values will match up with the footprint values printed on the PCB. The orientation of these components is important. You can either refer to the silkscreen print on the PCB or the above picture for the correct orientation.

This is a blue and white 3 legged component with the value 101 printed on it. Reference the above image for the correct position.

Loud Speaker:

A large 2 legged black circular component. Note that one end of the component is marked with a '+' sign. Reference the above image for the correct position.

Polyester Capacitors:
These are flat green 2 legged components and have the value 2A222 engraved on them. There are 3 of these capacitors in total. Reference the above image for correct positioning. Their orientation in not important.

Electrolytic Capacitor:
This is a black or blue cylindrical 2 legged component with a white (negative) stripe down one side and marked with the value 100uF. The orientation of this component is important. Note that in the above image the with stripe is to the outside of the PCB.

Visual inspection:
All the components should now be soldered to your PCB. Give your finished board a visual inspection and make sure that all the component legs on the underside of the boar are clipped so they cannot make contact with another component.

Power can be applied to the two remaining pads marked '-' (negative) and '+' (positive). You can power the metal detector from anything between 2.7 and 5V DC, however we find that it is at its most sensitive with a 3V supply (2x AA or AAA cells).

If you wish to use the included project case with battery connectors then we recommend soldering it to your board in the following configuration:


Tuning your metal detector:
To tune your metal detector, connect your power supply/batteries to it and carefully adjust the potentiometer until you hear a repeated clicking from the loud speaker. Then very slowly turn the potentiometer back in the opposite direction until you can no longer hear any clicks. It should now be tuned to its maximum sensitivity.

The contents of this guide are copyright Hobby Components Ltd and may not be copied, reproduced, or reused elsewhere without permission.

Tue Nov 11, 2014 12:15 pm

Joined: Sun Dec 21, 2014 10:56 pm
Posts: 5
Location: Cambridge, UK
Post Re: Metal Detector Kit + Project Case (HCKITS0028)
One of the pins of the loudspeaker is marked with + polarity, but in the assembly instructions the image is not clear enough to indicate whether the + should be connected to the top or bottom hole of the sound.out solder pads. Would appreciate some advice, thanks.

Having subsequently found a way to image-enhance the photo on the build instructions web page, it appears that the plus side of the loudspeaker connects to the upper pad of the sound.out solder pad.

Mon Dec 29, 2014 3:09 pm

Joined: Sun Dec 21, 2014 10:56 pm
Posts: 5
Location: Cambridge, UK
Post Re: Metal Detector Kit + Project Case (HCKITS0028)
Having read some fairly mixed reviews about commercially available cable detectors used for locating mains cables in plastered walls, I thought I would build this kit and see if it could do the same job for a much more reasonable price.

With some small modification of the inside of the top half of the case to allow the board to lie flat within the circular lip, the kit does appear to be very sensitive and easily and precisely detects live cables protected by steel capping underneath approximately a 10mm thickness of plaster.

The kit was tested with cable runs for which the location was accurately known. Now I'm hoping to make practical use of the kit to mark safe drilling positions for mounting pictures on various walls in my house (having first turned off the mains power while drilling !).

Good kit - recommended.

Mon Jan 12, 2015 3:39 pm
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