Small Temperature Controller

8 comments

Rate

devranjandas Active Contributor Join Date: Jun 2007 Posts: 24	Small Temperature Controller 07/01/2008 12:23 AM
	I have to provide a temperature control mechanism to control the ambient temeprature inside an enclosure of 5U, 155mm width and 200 deep. The heater to be used is around 50W power. Now since the space is very small, I cant afford to put a conventional temperature controller say from Eurotherm which are typically 48X48X80 (although smaller sizes may be available). Further due to space constraints and low power requirement I wouldnt like to use a thyristor for control. I would prefer a power transistor to do the job. Since standard controller give DC outputs in 0 to 10V. How to use DC voltage to control the power transistor. Can people suggest some solutions.
	Register to Reply
	Pathfinder Tags: temperature control

Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!

cnpower Guru Join Date: Sep 2006 Location: CHINA Posts: 2945 Good Answers: 14	#1 Re: Small Temperature Controller 07/01/2008 2:10 AM
	Do you know how transistor work? how is thyristor work? 50w is not large power, but what type amplifier do you adopt here to control the temp? pulse or analog? different type need different powe devices values.
	Register to Reply

ral412 Associate Join Date: Jun 2008 Location: Houston Posts: 30	#2 Re: Small Temperature Controller 07/01/2008 9:51 AM
	www.micropac.com This company makes small micro heaters, from thier selection 50 w heater would take at least 28 vdc. although if you contact them they may be able to build one that can work from 10 volts but that would mean that more than 5 amps is available for the heater to produce the available heat.
	Register to Reply

marcot Guru Join Date: Feb 2008 Location: Montreal, Canada. Posts: 1372 Good Answers: 80	#3 Re: Small Temperature Controller 07/01/2008 11:39 PM
	What about a simple bi-metal thermostat? Some of them are adjustable. __________________ Experienced is earned, common sense is taught, both are rare essentials of life.
	Register to Reply Score 1 for Good Answer

Snaketails Guru Join Date: Sep 2007 Location: Wrong end of the yellow brick road in Oz Posts: 930 Good Answers: 15	#4 Re: Small Temperature Controller 07/01/2008 11:51 PM
	How about a 1-wire temperature device connected to a PC, and the output driving the heater on-off signal? __________________ Qn, Whats the differance between a Snake and a Onion? Ans, No one cries when you chop up a Snake
	Register to Reply

devranjandas Active Contributor Join Date: Jun 2007 Posts: 24	#5 In reply to #4 Re: Small Temperature Controller 07/02/2008 12:04 AM
	Well I need a PID algorith and it shas to be an embedded function and the space available is very less
	Register to Reply

Snaketails Guru Join Date: Sep 2007 Location: Wrong end of the yellow brick road in Oz Posts: 930 Good Answers: 15	#8 In reply to #5 Re: Small Temperature Controller 07/02/2008 11:33 PM
	So, a 1-Wire device (typically a TO-220 or SOIC-8) for your monitoring device and a small 12V car incandescant globe for your heater, a couple of wires leading to a PC, or embedded PC card running a OS, so then you have Ethernet, and logging capabilities. Your space requirements are the space within the enclosure or for the complete unit? The PCB card I'm talking about is one from Advantech, I have 1 that is a 486, with a CF card-disk on the back, and I'm using it for my UPS/temperature monitoring and network shutdown controller. __________________ Qn, Whats the differance between a Snake and a Onion? Ans, No one cries when you chop up a Snake
	Register to Reply

Randall Guru Join Date: Aug 2005 Location: Hemel Hempstead, UK Posts: 5826 Good Answers: 322	#6 Re: Small Temperature Controller 07/02/2008 5:36 AM
	Use a Positive Temperature Coefficient (PTC) Resistor to control the base current in a power transistor. Both the transistor and heater element supply heat. Use a spread sheet to plot the performance: For a given current in R3 you know what the voltage is at the bottom of R4; Calculate the voltage which would be present at the junction of R1, R2 and R4 if the base of the transistor was not connected. Now the V_be at I_c enables you to calculate the current in the parallel combination of R1, R2 and R4 . And, this is the base current. Use the H_fe to calculate the collector current. The spread sheet needs to be in iterative mode. Check over the range of H_fes that R4 compensates reasonably for different gains. __________________ If you spend all your time looking for people and things to complain about: trust me, you will find plenty to complain about.
	Register to Reply

marcot Guru Join Date: Feb 2008 Location: Montreal, Canada. Posts: 1372 Good Answers: 80	#7 Re: Small Temperature Controller 07/02/2008 10:20 AM
	What is the budjet? What are the size requirements? What are the technical specs? __________________ Experienced is earned, common sense is taught, both are rare essentials of life.
	Register to Reply

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!

Copy to Clipboard

	Got Something to Say?
	Ask a Question Start a Discussion

	Aerospace
	BioMech & BioMed
	Chemical & Material Science
	Civil Engineering
	Communications & Electronics
	Education and Engineering Careers
	Electrical Engineering
	General Discussion
	Instrumentation
	Manufacturing
	Mechanical Engineering
	New Technologies & Research
	Software & Programming
	Sustainable Engineering
	Transportation

	Site Directories
	Forum Directory Blog Directory User Group Directory RSS Feeds CR4 Rules of Conduct CR4 FAQ Site Glossary Who's Online (52 right now) Show Members