Re: [time-nuts] Diodes as temperature sensors
Simple temperature sensors use the static diode characteristic, but a more accurate method is to use the slope of the characteristic, this is independent of individual diode parameters, though requires a little it more electronics to display. There are many papers on this back in the 1960/70s. Alan G3NYK From: Hal Murray hmur...@megapathdsl.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Cc: hmur...@megapathdsl.net Sent: Monday, 21 July 2014, 4:58 Subject: Re: [time-nuts] Diodes as temperature sensors alw.k...@gmail.com said: Apparently, the forward biased silicon diode was temperature sensitive enough that a small D.C. amplifier could drive a meter to read-out with reasonable accuracy. Well, maybe not accurate by Time-nut standards but close enough for its intended purpose. I think that mechanism is widely used for silicon temperature sensors. There is one (or more) on most modern CPU chips as well as special temperature measuring chips such as the Maxim/Dallas DS18B20 and DS18S20. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Diodes as temperature sensors
Back in the 1970's I was tasked with coming up with a thermometer that could be read in the studio of an AM radio station. I bought a Heathkit indoor-outdoor unit. It worked great at night but was all over the place in the daytime when the AM transmitter was on the air. Turned out the sensor was just a silicon diode forward biased. A small ceramic capacitor across the diode sensor fixed the RF sensitivity. Apparently, the forward biased silicon diode was temperature sensitive enough that a small D.C. amplifier could drive a meter to read-out with reasonable accuracy. Well, maybe not accurate by Time-nut standards but close enough for its intended purpose. A lot of better audio amplifiers use a silicon diode as a temperature sensor in the output stages to sense the case temperature to control the biasing and prevent thermal run-away. Seems like there are IC's that contain two diodes, one as a sensor and one as a heater. Part numbers escape me now. Al, retired, mostly ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Diodes as temperature sensors
On Sun, Jul 20, 2014 at 7:07 PM, Al Wolfe alw.k...@gmail.com wrote: Seems like there are IC's that contain two diodes, one as a sensor and one as a heater. Part numbers escape me now. You might mean the TMP36 family of sensors. They use diodes and must be the most common sensor out there. They are cheap and ultra-easy to use. But when I tried to use one to measure an FE5680 Rubidium oscillator I got a LOT of noise. I had to take ten or more reading and average them. Then I use shielded cable and place an RC filter near the sensor with only slight improvement. Likely I'm still making some kind of design error. But I moved on to one with a digital I2C output and it worked better.I was trying to moderate the fan speed to keep the Rb at constant temperature. The fan controller works well enough now. Here is a really good write up from the place I bought mine from tmp36-temperature-sensor/overview https://learn.adafruit.com/tmp36-temperature-sensor/overview -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Diodes as temperature sensors
alw.k...@gmail.com said: Apparently, the forward biased silicon diode was temperature sensitive enough that a small D.C. amplifier could drive a meter to read-out with reasonable accuracy. Well, maybe not accurate by Time-nut standards but close enough for its intended purpose. I think that mechanism is widely used for silicon temperature sensors. There is one (or more) on most modern CPU chips as well as special temperature measuring chips such as the Maxim/Dallas DS18B20 and DS18S20. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
