This is a device which basically uses an electromagnet to life small metallic objects from the ground. The device has internal power supply and can be used anywhere.

Main features:

1. It has a retractable stick which has a handle on one side and an electromagnet at the other end. The stick can be closed when not in use (approximately 30cm long). When it is to be used it can extended to about 70-80cm.
2. The handle of the device has a holder for the battery to power the electromagnet.
3. The handle also has a button to activate the electromagnet and also thus saving the energy of the battery when not in use.
4. From the battery the power wires run into the retractable stick towards the other end where the electromagnet is attached.
5. The electromagnet used in this device is an iron-core electromagnet. It has a circular shape. Also it can easily be attached and detached from the retractable stick for storage and comfort.
6. The electromagnet is attached to the stick in such a way that it easily spin around the axis of the hinge, so that it can easily align itself to the surface of the object it will pick.
7. The shape of the electromagnet is such that it will produce maximum force using the 18v battery supply.
8. The electromagnets can varied in size. The biggest magnet will have a diameter of 4 inches. The smaller electromagnets are lighter in weight but they will be less powerful.

Electrical circuit:

The circuit wiring of the device is quite simple. The battery is directly connected to the electromagnet with a switch in between to break and make the circuit. The polarity of the battery is irrelevant in this case. The battery to be used in this device is a 5 cell lipo battery.

The specifications of this battery are; Net Weight 610 capacity (mAh) 5000 max burst discharge (C) 40 max cont. current (A)  100 Length (mm) 145 width (mm) 48 Thickness (mm) 40 connector type 4.0mm Banana Connector Vol. Gap ~18.5V To install the battery simple connect the one end of the connector of the battery to the switch and the other end to the electromagnet. The battery fits in inside the housing of the handle, from the bottom of the handle just like the magazine of a gun. The battery can be obtained from http://www.hobbypartz.com/83p-5000mah-5s1p-185-20c.html

Electrical specifications of the Electromagnet: Details of the calculations are mentioned in the excel file. Considering the power consumption of the electromagnet and the battery power available the device can easily provide continuous electromagnet force for more than 4 hours. The electromagnet can lift up to 25N of force. A connector similar to the one used for the battery or any two wire connector will be attached to the electromagnet so that it easily be attached and detached.

Precautionary measures:

1. Don’t short the terminals of the battery.
2. Use the wire which is used to make coils. This wire has a thin layer of insulation on it. Don’t use ordinary wire for electromagnet.
3. Use a normally insulated wire for making the connections between the electromagnet and the battery.
4. If the wire is getting hot too rapidly turn off the battery. Chances are that the insulation is broken somewhere.
5. Don’t over discharge the battery. A good scheme is use the battery for 50% power and then recharge.