project

james.fung

hi guys,
Im new to this kind of stuff and i was hoping you guys could help

My project entails creating a device that cools IV fluid to 4 degrees C. I want to measure the temperature of this fluid and keep the fluid at 4C. So thus i was thinking of using a IR temp sensor with a feed back loop and alarm. The feed back loop would turn my power supply on and off depending on the temperature for regulation.

For example, my fluid rose from 4 C to 6 C, thus my device would turn on
fluid dropped from 4 to 2C my device would turn off
fluid rose to 10 C ( alarm would sound and would turn on)

However i don't exactly know what parts to get.

I was thinking of getting this:
MLX90614 Infrared Thermometer Module (90° FOV). I assume the BASIC Stamp 2 is the microprocessor?
How do i load My program to this micro processor?
What other parts do i need to buy?
What would be a good alarm, and LED display(to show temp of fluid at all times)?

Ps. please don't assume i know anything... because i don't..

Thanks for all help in advance.

Leon

How accurate does the temperature control have to be? You might need to use a PID controller.

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Leon Heller
Amateur radio callsign: G1HSM

james.fung

+- 4 degrees C. Do you think a PID is necessary given these requirements PID seems like it would increase my cost alot(+$40)? Im looking at

JLD7100 Temperature Controller

Specification
Power:AC(85V~265V) or DC(85V~360V)
Power consumption: 2Watt<
Range:-1999~9999
Sampling: 4/s
Relay output AC220V, 3A
Multiple sensor: T,R,J,B,S,K,E,Wre3 ~ Wre25 , PT100, Cu50
Accuracy: 0.2%
Dimension: DIN: 1/16 (48mmX24mmX75mm)
Hole: 45mmx22mm

james.fung

sorry i think the name is actually TET-7100 Intelligent Temperature Controller

Spiral_72

+/- 4C should be no problem WITHOUT a PID controller (I think)

The BS2 is the microcontroller, Yes. It's programmed through the RS323 port (serial port) on your computer OR a USB to serial adapter available from Parallax. A variant of BASIC is the language.

Just a couple thoughts:

Since IV fluid needs to be sterile, I'd think you need a non-contact sensor, or outside the fluid....

Buzzers for the alarm is available through Parallax, or Radio Shack.

7 segment LED displays would be the easiest to use (I think) and probably the cheapest. LCD would be MUCH nicer and more expensive / and potentially more difficult to interface for the beginner.

I don't have any ideas on selecting the temp probe. It will probably be 0-5V, 0-10V, 0-40mA or some variety of voltage or current. In any case you'll need a ADC for arguably the best precision, or use the RCTIME command might work just as well without the ADC (Analog to digital converter)

Cool project. What will you use for the heater / cooler??? Peltier?

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"puff"...... Smile, there went another one.

kf4ixm

Parallax also sells a 10 degree fov ir sensor also that may work better than the 90 degree fov, cut down on interference from the sides as i suspect you will be measuring the fluid as it flows through tubing or such. also a serial lcd module may work better as it's more easy to interface with the stamp. Also, Parallax has an outstanding Educational kit called Process Control (found here) that has a project inside that does pid temperature control using the basic stamp, and could easily be intergrated into what you want to do with your project. I would highly recommend getting this kit with a Basic Stamp Board of Education. With both of these kits, the 10 degree fov ir sensor and a serial lcd, and maybe a few other parts you would be able to build the system you want.

Hope this helps!

james.fung

Thanks for all of your help guys! this is really helping me think this though!

Spiral -- im definetly using a IR sensor. And i meant LED not LCD [noparse]:)[/noparse] . And yes im using a peltier!

kf4ixm- the 10 degree might be worth it for the extra 10 dollars. I might have to use the RS323 port instead of the educational board, i dont think i can drop 100 on a usb adapter( my teachers might not agree to pay for that)

SRLM

Sprial said...
LCD would be MUCH nicer and more expensive / and potentially more difficult to interface for the beginner.

Personally, I think the LCD is easier to use. All you need is a SEROUT statement, while a 7 segment display requires figuring out how to display a string of letters and multiplex them or otherwise control it.

@James - you could also use the homework board, although my searching right now has shown that apparently Parallax doesn't sell them in individual sets (just a 10 pack). Anyway, you could also go with a BS2 module and get a carrier board, assuming that you know or are willing to learn how to solder.

For your display I'd just use four LEDs: one for normal, one for low temperature, one for high temperature, and one for dangerous out of range temperature.

The temperature sensor does not have a BS2 onboard that you can program. You will need an external microcontroller. There are also other (read cheaper) microcontrollers out there, but they are more difficult to use and take more background knowledge. The Propeller from Parallax is one.

Finally, a PID controller would be a software feature, not a hardware feature. It wouldn't cost you money, unless you charge for your programming time.

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Spiral_72

I'm pretty sure you can drive a peltier PWM, so ya COULD write your own PID routines.... It'd probably be just PD though [noparse]:)[/noparse]

A lot of computers (laptops) are being shipped RS232 delete, so the USB adapter is required. If you can run RS323, do it.

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"puff"...... Smile, there went another one.