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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Ambient temperature sensing
Hi,
I'm looking for a circuit that will represent temperature ranges up to 60 degrees (celcius) using at least 3 LED's or transistors as the outputs for each range, but I DO NOT want a digital display like a 7-segment or LCD though. I want to be able to utilize these outputs to control others parts of my circuitry (perhaps like voltage calibration). Example: LED 1 (green) = -10-20 degrees, LED 2 (yellow) = 20-30 degrees, LED 3 (red) = 40+ degrees, I am open to all suggestions. Thanks in advance. J |
#2
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Ambient temperature sensing
"Jason S" bravely wrote to "All" (01 Dec 05 21:12:24)
--- on the heady topic of "Ambient temperature sensing" JS From: "Jason S" JS Xref: core-easynews JS sci.electronics.repair:350096 JS Hi, JS I'm looking for a circuit that will represent temperature ranges up to JS 60 degrees (celcius) using at least 3 LED's or transistors as the JS outputs for each range, but I DO NOT want a digital display like a JS 7-segment or LCD though. JS I want to be able to utilize these outputs to control others parts of JS my circuitry (perhaps like voltage calibration). JS Example: JS LED 1 (green) = -10-20 degrees, JS LED 2 (yellow) = 20-30 degrees, JS LED 3 (red) = 40+ degrees, JS I am open to all suggestions. JS Thanks in advance. J, You might try crossposting to sci.electronics.design. Your circuit needs a voltage reference and a window comparator. The voltage reference is used with a temperature probe and the window comparator will divide your output into 3 ranges. With some cmos gating you can readily light 3 separate leds. A*s*i*m*o*v .... I worked hard to attach the electrodes to it. |
#3
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Ambient temperature sensing
Jason,
You could try the LM34 and LM35 series of temperature sensors from National Semi. There output is linear with temp. 10mv/degrees F for the LM34. The LM35 is 10mv/degrees C. The output can then drive a few comparators with the appropriate trip points. http://www.national.com/ds/LM/LM34.pdf http://www.national.com/ds/LM/LM35.pdf -- Tony Marsillo Nutmeg Repair ----------------------------------------------------------------- "Jason S" wrote in message ... Hi, I'm looking for a circuit that will represent temperature ranges up to 60 degrees (celcius) using at least 3 LED's or transistors as the outputs for each range, but I DO NOT want a digital display like a 7-segment or LCD though. I want to be able to utilize these outputs to control others parts of my circuitry (perhaps like voltage calibration). Example: LED 1 (green) = -10-20 degrees, LED 2 (yellow) = 20-30 degrees, LED 3 (red) = 40+ degrees, I am open to all suggestions. Thanks in advance. J |
#4
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Ambient temperature sensing
Jason S wrote:
Hi, I'm looking for a circuit that will represent temperature ranges up to 60 degrees (celcius) using at least 3 LED's or transistors as the outputs for each range, but I DO NOT want a digital display like a 7-segment or LCD though. I want to be able to utilize these outputs to control others parts of my circuitry (perhaps like voltage calibration). Example: LED 1 (green) = -10-20 degrees, LED 2 (yellow) = 20-30 degrees, LED 3 (red) = 40+ degrees, I am open to all suggestions. Thanks in advance. J How about an analog bargraph IC? Otherwise a quad comparator chip could be setup to do this, IIRC the LM329 is such a chip. |
#5
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Ambient temperature sensing
"James Sweet" wrote in message news:1ZOjf.1374$fY3.718@trnddc01... Jason S wrote: Hi, I'm looking for a circuit that will represent temperature ranges up to 60 degrees (celcius) using at least 3 LED's or transistors as the outputs for each range, but I DO NOT want a digital display like a 7-segment or LCD though. I want to be able to utilize these outputs to control others parts of my circuitry (perhaps like voltage calibration). Example: LED 1 (green) = -10-20 degrees, LED 2 (yellow) = 20-30 degrees, LED 3 (red) = 40+ degrees, I am open to all suggestions. Thanks in advance. J How about an analog bargraph IC? Otherwise a quad comparator chip could be setup to do this, IIRC the LM329 is such a chip. Hi thanks for the reply. The quad comparator wouldn't really work, because only 1 'output' LED/Transistor needs to be lit at any given time, not more than 1. The analog bargraph would probably work, but would need to be able to set it up as 'Dot' mode (probably easy to do), then I could use logic gates to provide filtering from each of the outputs to produce my final 3 or 4 output ranges. However, any ideas on how to hook up a temperature sensor to it? I found schematics based on voltage measurement, not I know nothing about temp sensors and how I would hook it up with this type of circuit. Can you point me in the right direction? Thanks, J |
#6
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Ambient temperature sensing
Jason S wrote:
"James Sweet" wrote in message news:1ZOjf.1374$fY3.718@trnddc01... Jason S wrote: Hi, I'm looking for a circuit that will represent temperature ranges up to 60 degrees (celcius) using at least 3 LED's or transistors as the outputs for each range, but I DO NOT want a digital display like a 7-segment or LCD though. I want to be able to utilize these outputs to control others parts of my circuitry (perhaps like voltage calibration). Example: LED 1 (green) = -10-20 degrees, LED 2 (yellow) = 20-30 degrees, LED 3 (red) = 40+ degrees, I am open to all suggestions. Thanks in advance. J How about an analog bargraph IC? Otherwise a quad comparator chip could be setup to do this, IIRC the LM329 is such a chip. Hi thanks for the reply. The quad comparator wouldn't really work, because only 1 'output' LED/Transistor needs to be lit at any given time, not more than 1. The analog bargraph would probably work, but would need to be able to set it up as 'Dot' mode (probably easy to do), then I could use logic gates to provide filtering from each of the outputs to produce my final 3 or 4 output ranges. However, any ideas on how to hook up a temperature sensor to it? I found schematics based on voltage measurement, not I know nothing about temp sensors and how I would hook it up with this type of circuit. Can you point me in the right direction? Thanks, J Use a darlington transistor, for silicon the leak current doubles every 6 degrees celcius,and the leak current of the first transistor multiplied twice by your current gain should be around the Milliamp range.Up to about 100 degrees,works nicely. Add 3 comparators to check for voltage level across a suitable resistor,you could use a quad IC 741 type for that. |
#7
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Ambient temperature sensing
Hi thanks for the reply. The quad comparator wouldn't really work, because only 1 'output' LED/Transistor needs to be lit at any given time, not more than 1. The analog bargraph would probably work, but would need to be able to set it up as 'Dot' mode (probably easy to do), then I could use logic gates to provide filtering from each of the outputs to produce my final 3 or 4 output ranges. However, any ideas on how to hook up a temperature sensor to it? I found schematics based on voltage measurement, not I know nothing about temp sensors and how I would hook it up with this type of circuit. Can you point me in the right direction? Thanks, J A quad comparator has four outputs, there's four comparators, seems like it would do exactly what you need. |
#8
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Ambient temperature sensing
On Thu, 1 Dec 2005 20:45:56 -0500, "Tony Marsillo"
put finger to keyboard and composed: Jason, You could try the LM34 and LM35 series of temperature sensors from National Semi. There output is linear with temp. 10mv/degrees F for the LM34. The LM35 is 10mv/degrees C. The output can then drive a few comparators with the appropriate trip points. http://www.national.com/ds/LM/LM34.pdf http://www.national.com/ds/LM/LM35.pdf I'd suggest an LM35 plus an LM3914 bar graph driver. -- Franc Zabkar Please remove one 'i' from my address when replying by email. |
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