THERMOMETER PROJECTPCB ASSEMBLY INSTRUCTIONS

ASSEMBLING THE PCBHold the PCB as shown.

Now go through the components to ensure you can identify each one

Label Component No.

R1-6 150Ω Resistor (brown, green, brown) 6

R7 20KΩ Resistor (red, black, black, red) 1

TS 22KΩ Thermistor (@25 C) 1

C1 1uF Ceramic Dipped Capacitor 1

LED1-12 3mm Red LED 12

IC1 12F675 IC 1

8pin DIL IC Holder 1

2xAA Battery Holder with leads 1

RESISTORSThere are 7 resistors in all.

R1 to R6 are all 150 ohms in value. They can be placed either way round.

R7 is a low tolerance type which is blue with 5 coloured bands. It can also be inserted either way round.

IC HOLDERThe IC holder is for the IC. It is optional but a good idea to use it. The holder has a notch at one end. This should face downwards.

CAPACITORThere is one 1uF ceramic dipped capacitor. It has the numbers “105” written on one side.

This can be inserted either way round as it in a non-polarised type.

It will be either blue or yellow in colour.

LEDs

These can be pushed all the way into the PCB, use a spacer (6mm) to space the LEDs far enough from the PCB to clear the other components.

There are 12 LEDs. They must be inserted the correct way round. The LED has a flat section on the rim of the LED to denote the negative. This is clearly shown on the PCB, and how each LED is inserted the opposite way round from the ones next to it.

6mm spacer

THERMISTORThe Thermistor inserts below the IC holder. It can be inserted either way round. The wires are long so it can be soldered some distance from the board and positioned where required.

Make sure the wires do not touch together otherwise the reading will stay at 30 degrees.

POWER LEADSThe power leads from the battery holder are inserted up through the large hole in the PCB marked “Wire” and then back through the holes marked “+v” and “0v”. This prevents them from breaking off. Solder these wires to the pads underneath.

INTEGRATED CIRCUITThe IC can now be inserted into the IC holder. Make sure the notch on the case of the IC is facing downwards and all the pins are inserted correctly.

To ease IC insertion, carefully pinch the rows of legs inwards slightly to help align them. ICs generally have their legs set slightly apart from manufacture.