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Climate Controller

Measures temperature and/or humidity

Climate Controller
This project provides the ability to control two separate devices, such as an electrical heater and an extraction fan, based on the measured humidity and temperature. Despite the modest number of components, this circuit does offer a large number of settings and is even equipped with a serial interface for communication with your PC.
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Temperature range: –40°C to +125°C, resolution 0.1°C Humidity settings range: 0% – 99%, resolution 1% Setting range for temperature hysteresis: max. 5°C, resolution 0.1°C Setting range humidity hysteresis: max. 10%, resolution 1% Outputs can be controlled by combinations of higher or lower temperature than the threshold and/or higher or lower humidity than the threshold Adjustable continuation time after the temperature and/or humidity threshold has been passed, in the range from 1 to 99 minutes (separately adjustable for each output) Optionally switch on each output separately after an adjustable period from 1 to 99 hours of inactivity; the output then stays on for the above-mentioned continuation time Option to switch on one or both outputs for 1 to 99 minutes after the circuit is powered on Display of the status of the outputs and the actual temperature and humidity and the option of switching the outputs on and off remotely using the RS232 interface
Component List
Resistors
R1,R2 = 220Ohm 1W
R3,R9,R12 = 2.2kOhm
R4,R5,R6 = 330Ohm
R7 = 2.4kOhm
R8 = 5kOhm trimpot, horizontal
R10,R13,R18 = 22kOhm
R11,R14–R17 = 100kOhm
Capacitors
C1 = 220µF 25V, radial
C2,C3,C11 = 100nF
C4 = 10µF 16V, radial
C5,C6 = 100nF 400V, class X2
C7–C10 = 1µF 16V, radial
C12,C13 = 15pF
C14 = 330nF
Semiconductors
D1,D2 = 1N4148
B1 = DF04 bridge rectifier (280V piv, 1A)
LEDs, 3mm, for SV1, 3 pcs
T1,T2,T3 = BC547
IC1 = 7805T
IC2 = PIC16F887P
IC3 = MAX232
Miscellaneous
TR1 = power transformer, PCB mount, 9V / 2.8VA secondary (e.g. Weiss EI 30/23 BV 85/341)
Q1 = 20MHz quartz crystal
X1,X2,X3 = 2-way PCB screw terminal block, 0.2’’ lead pitch
K1,K2 = PCB relay with DPDT contacts, 250V / 5A, 12V coil (e.g. Panasonic JW2SN-DC12V)
SV1 = 6-pin pinheader, 0.1’’ pitch
SV2 = 3-pin pinheader, 0.1’’ pitch
SV3 = 8-pin pinheader, 0.1’’ pitch
SV4 = 4-pin pinheader, 0.1’’ pitch
X4 = 16-pin pinheader, 0.1’’ pitch
LCD, 2x16 characters, e.g. Gleichmann GE-C1602B-YYH-JT/R, Conrad Electronics # 183043 - 89
Humidity and temperature sensor with I2C interface, type IST HYT221 (Conrad Electronics #, 505671 - 89)
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