Step 4: Circuit Assembly Part 1

Here's a shopping list for electrical components:
Qty Sch Ref Name Value Package Rating Notes
1 C3 Tantalum Capacitor 10 uF 1206 6V or Greater  
4 C4, C5, C6, C7 Ceramic Capacitor 0.1 uF 0805 or 0603 6V or Greater  
2 C8, C9 Ceramic Capacitor 22 pF 0805 or 0603 6V or Greater  
1 C10 Aluminum Caoacitor 47 uF or greater 6.6mm x 6.6mm 6V or Greater  
1 C11 Tantalum Capacitor 4.7 uF 1206 6V or Greater  
10 C1, C2, C12 to C20 Ceramic Capacitor 1 uF 0805 or 0603 6V or Greater  
1 IC1 LM1117 3.3V SOT-223    
1 JP1 Male Header 3x2 0.1" Pitch   Standard 6 Pin ISP Header for AVR
1 JP2 Screw Terminal 2 Pins, SparkFun PRT-08084 3.5mm Pitch   For thermocouple
1 Q1 Crystal 16 MHz HC49 SMD 20 pF, +/- 30 PPM  
2 R1, R2 Chip Resistor 22 Ω 0805 or 0603 1/10 W, +/- 10%  
4 R3, R4, R7, R8 Chip Resistor 10 kΩ 0805 or 0603 1/10 W, +/- 10%  
1 R6 Chip Resistor 330 Ω 0805 or 0603 1/10 W, +/- 10%  
2 S1, S2 Button Switch TL3330      
3 S3, S4, S5 Button Switch TL6120DF     Must be super tall
1 USB USB Mini-B Female Connector UX60A-MB-5ST SMD   My favorite, easy to solder, flat bottom
1 LCD LCD COG Graphic Display NHD-C160100DiZ 160x100 Pixel    
1 LCD FPC Connector A100284CT, 1-1734592-4 14 Pos, 0,5mm Pitch,
Right Angle SMD
1 U1 AVR Microcontroller ATMega32U4-AU 44 TQFP    
1 U2 Thermocouple Amplifier AD595AQ 14 DIP    
1 U2 Chip Socket 14 Pins 14 DIP    
1 Relay Solid State Relay D2425 by Crydom   240 VAC, 25 A  
1 JP2 Thermocouple,
type K
by Test Products Int
  -40 to 510 °C  
1   USB Wall Charger     120V or 240V AC to 5 V DC, 1000 mA Used as wall AC to 5V DC converter
1   Cooling Fan 5V DC 40mm x 40mm,
10mm to 17mm thick
1   AC Extension Cord   16 AWG or Thicker 300V  

Solder these components to the PCB, follow the PCB design.

To get a PCB, download the project files, and send the Gerber files to a PCB manufacture. I used Seeed Studio 's Fusion PCB Service, it'll cost you $29 for 10 pieces.

Most components are 0805 (but can be substituted with 0603), everything on the PCB can be hand soldered. Surface mount soldering is easy, as demonstrated in my video:

There are several special connections you need to make, see the diagrams in the gallery about the following:
  • You need to solder a thick extension cord to the circuit. I live in North America, so one wire is "hot" and one wire is "neutral". Your country might use a slightly different system, but if you don't mix up the wires, this circuit should also work for your country.
  • As I mentioned before, a cheap USB charger is used as 5V DC power supply that converts AC power to DC power. After you hack that charger (the instructions will be in another "Instructable Step"), the diagrams show you where to make the connection.
  • I used velcro to attach the LCD to the PCB. Connect the flat cable into the FPC connector. Solder the backlight wires to the connection for the backlight.

You need to put a lot of solder onto the wide exposed AC tracks so it can handle the large amount of electrical current.

Clean the PCB using alcohol or flux cleaner. Leaving flux on the PCB might cause inaccurate readings from the AD595AQ.

The schematic has some notes on it, I hope you read them.
Zenock3 years ago
Do you think you could get the same vibrating action from an electric toothbrush?
wespow13 years ago
on the button switch would something like this work? http://www.ebay.com/itm/120770287927?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649#ht_2766wt_1163
frank26080115 (author)  wespow13 years ago
yes it will work

it'll look kind of ugly though