Project:Sanguinololu Thermocouple

[[|Sanguinololu Thermocouple]]
Created	03/11/2012
Version	1
Members	Pinski1
Project Status	Awaiting PCBs
QR code

Introduction

I wanted to add a thermocouple to my 3D printer's hot end. Ideally it would improve the quality of my printed objects as it would provide more accurate temperature readings with greater immunity from electronic noise generated by the stepper motors.

Features

The PCB I have designed has the following features:

• Fits onto the expansion headers already present on the Sanguinololu
• Adds a MAX31855 thermocouple to digital convertor chip
• Enables temperature readings between -200°C to +1350°C ±2°C
• Has a resolution of 0.25°C
• Can sample at 10Hz

Files

Schematic

The Eagle 5.11 schematic file.

PCB Layout

The Eagle 5.11 board file.

Bill of Materials

Qty	Value	Ident	Description
1	TXB0104D	IC1	SOIC14 Bi-Directional level translator chip
1	TPS73033DBVT	IC2	Could be any SOT23-5 +3V3 voltage regulator
1	MAX31855KASA+	IC3	SOIC8 Thermocouple-to-Digital chip
2	2.2uF	C1, C2	Ceramic 1206 decoupling capacitors
3	10nF	C3, C4, C5	Ceramic 0805 decoupling capacitors
1		SV1	2x5 way, straight, 2.54mm, female header
1		X1	2way, screw terminal, 5.08mm
1			Thermocouple, K Type

Pictures

Top	Bottom
		The Eagle CAD layout.
		The Eagle CAD 3D render
		The PCB renders of OSH Park
To come	To come	The delivered PCBs.

How to Build

Tools required:

• soldering iron
• solder
• tweezers

Tools that would be useful:

• solder sucker
• solder wick
• magnifier

Soldering

1. Start by soldering the MAX31855KASA+ into position. Ensure pin 1 is correct and all the pins are lined up.
2. Next solder in the TXB0104B, agin ensure pin 1 is correct and the pins line up.
3. Solder in the final IC the +3V3 reg. This is the smallest package so special care will need to be taken to ensure the pins like up correctly.
4. With the ICs done now solder in the passives. Start with the larger 1206 2.2uF capacitors, these will only fit in two places.
5. Then solder in the smaller 0805 10nF capacitors, there should be 3 of these.
6. With the surface mount components in place put the 2x5way female header such that it points out the bottom of the board (see the render) and solder it.
7. Finally solder in the 2way screw terminals

Testing

You will need a Bus Pirate or something equivalent to communicate with the board and a K type thermocouple to sense the temperature.

Function	Pins		Function

Licence

This design is licensed under Creative Commons BY-NC-SA

This design is modified from Sanguinololu SD