Friday, September 3, 2010

DIY laser spirograph (part 4)

How to build spirograph controller from a kit. Step by step assembling guide.

NOTE!!! Given information is provided for visual reference and may not reflect latest design changes and modification but every ordered kit supplied with updated schematic and component map. 

Kit includes PCB, preprogrammed with latest firmware microcontroller PIC18F1320 and all electronic components to build controller for advanced laser spirograph.

Complete part list:
1 x Capacitor 100nF          
1 x Pol Capacitor 100uF      
2 x Pol Capacitor 10uF          
1 x Diode 1N4148           
3 x 2N7000 MOSFET           
2 x Resistor 10K          
4 x Resistor 330R            
3 x Potentiometer 10K          
1 x Resistor 10R          
1 x Resistor 240R          
1 x Potentiometer 1K          
1 x SPDT Toggle Switch       
1 x preprogrammed microcontroller PIC18F1320    
1 x MC78M05ACT Voltage Regulator   
1 x LM317BT Adj Voltage Regulator   
1 x DIP-18 socket           
1 x ICSP Header, 5-Pin       
1 x PCB                

As electronic device, controller is pretty simple and assembling requires only basic soldering skills and minimum set of tools:

 - multimeter;
 - soldering iron, liquid flux, wire solder;
 - fumes extractor (or work in well ventilated area);
 - tweezers, pliers, wire cutter, small flat screwdriver;
 - 22 AWG stranded wire;
 - alcohol, soft brush;
 - heat shrink tubing;
 - glue gun.

Step 1.

Make wire connections on top side of board.
There are 8 wire jumpers. 7 wire jumpers are marked by yellow color
Position of jumper #8 is determined by voltage, that should be applied to fans.
Controller supports 5V and 12V fans but they cannot be mixed, i.e. you can connect three 5V fans OR three 12V fans and correct voltage is set by shorting only ONE of two possible jumpers.

For 5V fans, green jumper (W1 on schematic) is short, red jumper (W2) remains open.
For 12V fans, red jumper  (W2 on schematic) is short, green jumper (W1) remains open.

Of course you don't have to deal with all wire jumpers if kit is supplied with double-sided PCB.
 In that case install only W1 (5 volts) or W2 (12 volts) jumper.

Factory made PCB.

Step 2.

Solder DIP-18 socket. Make sure you install it correctly; check position of pin #1.
Microcontroller chip may stay in socket while you are soldering it. It will keep socket's pins aligned in case of overheating and softening of socket during soldering.

Step 3.

Install resistors and 1N4148 diode.
Make sure you install diode correctly. Cathode end of diode is marked by wide black band.
You also can use multimeter to determine diode's terminals.
If you are like me, don't remember color codes of resistors by heart, use multimeter to check resistor's value. Some resistors are installed vertically.

Step 4.

ICSP 5-pin header is a optional feature and can be omitted. It's intended only for field reprogramming of PIC microcontroller and requires use of ICSP compatible programmer and dedicated software. Microcontroller can also be reprogrammed with any socket based PIC programmer.

Install 2N7000 MOSFET transistors. To avoid forming of solder bridges between leads of transistor, use plenty of liquid flux during soldering. Test all neighboring leads of transistors for short circuit with continuity tester.

Step 5.

Install ceramic and electrolytic capacitors. Make sure polarity of electrolytic capacitors is correct.
Install voltage regulators LM7805, LM317 and  1K potentiometer.

Step 6.

Install 10K potentiometers and toggle switch. Use heat shrink tubing to insulate wire joints.
Headers for other connections are optional and wires can be soldered directly to the board.
In the last case wires can be secured with drop of hot glue at the joint point where wire's connected to board.
When soldering is complete, clean board with pure alcohol to remove flux residue.
Spirogarph requires DC power supply 9V 1A for 5V fans and 12V 1A for 12V fans.

Low power laser modules usually require 2.8 - 4V.
Adjust output voltage (POT R12) before connecting laser module and check polarity when connecting laser.

Setting voltage for laser module.

(part 3) <<<--- DIY laser spirograph --->>> (part 5)

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