If you require accurate Celsius to Fahrenheit purchase the VK011 once the QK145 goes above 98F it displays incorrect temperature info.
Comes with 1 sensor but can support up to 4.
Provides real-time data via the serial port, by interfacing with up to 4 DS18S20 Dallas temperature sensors. It has an accuracy of 0.5 degrees centigrade. You must choose either Fahrenheit or celcius based on a jumper. There is no external power required for this kit, because it gets its power from the serial port. The data stream is easily logged & processed. You can run each sensor over 200m distance from the board.
We have provided one DS18S20 in this kit. This allows you to test the kit. If you need more sensors, you can buy them here. We also have not provide cables to connect between the kit and each remote sensor. But we do provide a harness and connector for easy connection of the cables to the PCB. We have not tested the maximum distance which the sensors can be located from the PCB but believe it to be much more than 200 meters/yards.
The source code for the software inside the microcontroller is available from the developer.
First check the components supplied against the Component Listing. Follow the overlay on the PCB to assemble the kit. If you want to measure degrees Fahrenheit then add the Link 'F' to the board where shown. The default measurement is in degrees Centigrade, or you can add the Link at the 'C' position. The pin-out of the DS18S20 is shown here. You can easily determine how to connect the sensor to the 3-wire harness by looking at the back of the PCB to see which is the ground connection. Or you can go by the harness color: red is GND, yellow is VDD and the middle wire black, is the signal line.
The wiring harness pin location versus color can change. Always check pin locations, not colors.
The color codes on the wire mean nothing, if they did Red would be +5, Black would be ground and yellow would be the data line.
No external power is required. The kit is powered from the serial port of any type of computer. Some serial ports do not put out enough voltage, if you have issues try another serial port on another PC.
There are several ways to read the temperature data. You have to use a terminal program set to 2400 baud, 8 bits, no parity, 1 or 2 stop bits. The easiest way is to use Hyperterminal. Use the capture to log or save data. You can write your own program in BASIC using the INPUT command to capture the data as it comes in.
We believe the sensors may be located more than 200 yards from the PCB. Just check that the remote VDD is above 4.4 Volts. The kit designer recommends 10uF tantalum capacitors be placed across the power supply pins (not supplied) to minimise random errors and possibly get increased range. If power supply from your serial port is a problem you could use a lower current drawing 5 voltage regulator.
Here is a link to a web page of someone who has this device operating in and around his household. He has also made his code available to anyone who is interested: http://www.klein.com/assets//thermd//thermd" target=_blank
2K2 resistor 5% R1 R2 R3 R4 4 100uF mini C1 1 Mono 104 C2 1 1N4004 D1 1 10uF mini C3 1 78L05 IC1 1 Programmed 12C509 /P04 IC2 1 8 pin IC socket 1 DS18S20 1 DB9 Right angle Female connector 1 3 pin header and cable DS1 DS2 DS3 DS4 4 QK145 PCB 1
The DS18S20 is a digital thermometer featuring ﾱ0.5C accuracy over a -10C to +85C range. Data is read out over a 1-Wire serial bus in 2's complement format with 9 bits of resolution.
ﾱ0.5C accuracy from -10C to +85C Measures temperatures from -55C to +125C (-67F to +257F) 9-bit (expandable) resolution 1-Wire interface requires only one port pin for communication 64-bit unique and unchangeable electronic serial number Multi-drop capability for simplified distributed temperature sensing Alarm function with user-defined nonvolatile alarm settings No external components required to measure temperature 3.0V to 5.5V supply range Optional "parasite-power" operation (power derived directly from 1-Wire bus) TO-92 (DS18S20) and 150mil 8-pin SO (DS18S20Z) packages Thermostatic Controls