In Progress

Power and temperature controller

No time wasters please, please only bid if you can complete the project!

Design and prototype power circuit that have the following features:

1) Regulate power by way of adjusting the duty cycle by using triacs firing at zero crossings. The firing is controlled by a PIC chip, the firing cycle is adjustable in increments of 1% (from 1% to 99% of designed power of 3KW (20 Ohm resistance at 240V)). The adjustment is via two push buttons and the adjusted settings shall be stored in flash. Two LEDs shall indicate power adjustment (green = -1%, red = +1%). Status reading shall be done by pushing both buttons together and a readout shall be done by flashing of the LEDs (red = 10%, green = 1%. Example: 51% = 5 x red + 1 x green). The PIC chip should be easily programmed using MPlab IDC 2 through a programming port mounted on the PCB.

2) There should be a safety program that monitor voltage drop or other indicators which co-relate with no load (circuit open=no resistance) or faulty Triac. Upon no load, power output from the circuit should be cut. This safety program should always be the first thing running upon switching on of the unit. In the event of a fault (no load), after it cuts power output, it should repeatedly run the safety called self reset & self diagnostic. Another bicolour LED shall be used to show status (red = fault, green = Ok). This LED shall be remotely mounted on the end of a wire to allow it to be mounted elsewhere.

3) On top of this I would like to have a thermostat/temperature controller in the same circuit which will monitor surface temperature. The temperature sensor shall be as small as possible mounted remotely on a separate PCB or simply on the end of a wire. The temperature sensor should be easily taped or glued onto a flat surface. At a programmable high temperature limit (65 deg C standard), it should switch off the power, it should then switch it back on 5 degrees below this. This high temperature limits should be adjustable using a rotary dial (from 65 deg c to 35 deg c, smooth change), these setting should be programmable and not necessary to be very accurate (only the top limit of 65 deg C is critical, the lower settings are approximates).

4) The should be a maximum limit switch (basically a thermal fuse) which will cut off power to the unit at 105 deg C. A kind of worst case fuse.

5) The unit should be as square as possible, as small as possible, and can be fitted inside a standard 50.8 x [url removed, login to view] box.

6) If a heat sink is required, it should be as small as possible to be mounted within the same box.

7) 3 prototypes are required

8) Final deliverables are: complete design documentation (gerber file, operating manual, etc), 3 working prototypes, program (hex).

9) Due to time waster, I need this project to be completed ASAP.

Skills: Electronics

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About the Employer:
( 0 reviews ) Petaling Jaya, Malaysia

Project ID: #235654