i. Connecting K8067 temperature sensors to K8055 and K8055N boards

There are multiple ways to get temperature sensors connected to K8055 and K8055N boards. There are two Velleman kits K8067 and K6001, but you may also use the operation amplifier circuit from home automation subsection 2.c. K8067 and the circuit from subsection 2.c have analog outputs. Their signals can be lead directly to K8055 or K8055N board through A1 or A2 analog input. The boards have an inbuilt operational amplifier on both analog inputs (A1 and A2), which assure better linear response and better accuracy of the measured results. Extra amplification is not needed and K8055 or K8055N board can be connected directly to the analog output of the temperature sensor circuit.

Nevertheless, you may opt for a more sophisticated two stage amplification, where temperature sensor circuit only server as preamplifier and the K8055 or K8055N onboard operation amplifier server as a final amplification stage. These can be achieved by using a 50 k ohm trimmer on temperature sensor circuit (instead of 500 k ohm trimmer) and placing a 10 k ohm trimmer to the empty resistor terminals (R8, R9, R53 or R54 regarding the analog input used). The trimmer must be then adjusted to achieve desired amplification gain and thermistor readings accuracy.

There is of course an alternative option! Velleman K6001 kit temperature sensor circuit has an inbuilt pulse width modulator (CA3524) with impulse width of 0.5 ms to 2.5 ms. The temperature change response is 0,2 ms/°C. The pulse width can be accurately measured by a PC sound chip acting as a digital oscilloscope or by a PIC18FxxJ50 functional unit. These eliminate the need for buying a K6000 or a K6002 kit to be able to read the temperature from K6001 temperature sensor circuit. However, PIC18F2xJ50 must still be programmed to measure pulse width. We will discuss this matter in an upcoming Custom projects subsection.

Expert advice: Velleman K8055(N) and universal temperature sensor K8067