Parts you need to build your own launcher !

B1= 9V battery for triggering
C1 and C2= 2200uF 250V capacitor
D1= 800V 10 A bridge rectifier
L1= electromagnetic coil (100mohm resistance, 246µH inductance)
R1= 50 ohm 40watt resistor (charging)
R3= 1 K ohm ½ watt resistor (triggering)
S1= 600V 100A SCR
SW1= push button switch
T1= Variac
R2= 200 K ohm ¼ watt resistor (bleeder/balancing)
D2= 100A free wheeling diode
P1= Ferromagnetic projectile (12 gm weight)

Coil Design
-The most difficult and important part of the design

Factors to be taken into account during the coil design:
1)Inside diameter must fit snugly on the barrel or the firing tube.
2)Outside diameter should be large but must be within the constructional limitations.
3)Coil resistance should be small.
4)Saliency ratio must be high for effective coupling of the electromagnetic field and the Ferro magnetic projectile

For the RLC simulation a RLC simulation program has been used which helped in getting the perfect combination of the voltage, resistance, inductance and capacitance to get the best suited current waveform.


“The best suited current waveform”:
1)Maximum amplitude
2)The one which dies away to near zero in about the time it takes the projectile to reach the mid-point of the coil.

The basic guideline
A charged capacitor is made to discharge itself through this series RLC circuit consisting of the electromagnetic coil. The intention is to make the current delivered by the capacitor to be of very high frequency and amplitude. The discharge is initiated by a small gate pulse applied at the gate of an SCR placed in series with the capacitor. A protection diode, acting as a free wheel, can also be provided to allow the current to circulate in the coil, protecting the electrolytic capacitor from damage.

An electromagnetic linear accelerator consists of one or more coils in the configuration of a LINEAR SYNCHRONOUS ELECTRIC MOTOR which accelerate a magnetic projectile to high velocity

The name Gauss gun is sometimes used for such devices in reference to Carl Friedrich Gauss, who formulated mathematical descriptions of the magnetic effect used by magnetic accelerators. The first such operational accelerator was developed and patented by the Norwegian physicist Kristian Birkeland

We know when current flows through an electromagnetic coil, a magnetic field is produced in its neighbourhood. Here such a coil is made to carry a very high current. This produces a very large magnetic field thus pulling a projectile towards it’s centre. The field is designed to shut off when the projectile is at the centre of the coil.

the beastly bridge rectifier :)
Test Setup 1 ( projectile velocity of around 18 m/s)
THE coil ( made WITHOUT a winding jig :) )
Test setup 2

Here are some of the pictures of the coilgun that I made last year !
Projectile used : an artsy composition made with headless iron nails and feviquick !
Drop me a comment if you would like some technical details :)

the making of anabug 1

the making of anabug 1:
anabug 1 was primarily meant to be a line follower equipped with a colour sensor. The colour sensor was supposed to detect the colour of the line. The sensors that were used are LDR LED pairs. the LDRs used are fitted with a lens for increased sensitivity. The same sensor type was used for detecting colour.

What was anabug 1 supposed to do?
anabug was supposed to do one of two things: either follow a line (dark on light/light on dark) and detect the colour of the line and display the colour using different coloured LEDs. (Special thanks to Mr Wilf Rigter for his excellent article on colour sensors) or it was to avoid obstacles and detect the colour of the floor beneath it.

downsides of anabug 1:
the LDR based sensors are EXTREMELY prone to picking up noise or undesired signals. Also the response of anabug 1 to the stimuli provided by it's environment is kinda slow.

the detailed circuit diagram will be uploaded soon !

cheers to all fellow roboteers!