Microcontroller-Temperature Measurement Uses Only a Diode & a Capacitor - 12/05/08 EDN Design Ideas: Discharging a capacitor through the reverse leakage of a PN junction allows you to measure ambient temperature. Using a PN-junction diode for temperature measurement usually depends on its 2‑mV/K temperature coefficient. Conventionally, you must amplify and digitize this voltage with an ADC before you can use the value in a microcontroller. Less well-known is the fact that the reverse current of a PN-junction diode shows a good exponential dependency over temperature; increasing the temperature by approximately 12K doubles the leakage (Figure 1). An easy way to measure current over such a large range of two to three decades is to charge and discharge a capacitor and measure the time or frequency Design by Andreas Grun Over-Temperature Micro-Power Alarm - The circuit is powered for years by a single 3 volt lithium battery. it sounds an alarm when the temperature exceeds a certain point. With some minor changes the circuit could also be configured for an under temperature (freeze) alarm. The circuit uses a . . . Hobby Circuit designed by David A. Johnson P.E.-June, 2000
Peltier Element Controls Itself - 10/27/94 EDN Design Ideas: Peltier elements, or semiconductor heat pumps, combined with heat sinks are a designer's choice when controlled low temperature is required for CCDs and high-density IC s. These devices are suitable for device temperature cycling in reliability tests Design by Dmitrii Loukianov, Moscow, Russia
PIC Projects: Digital Temperature Controller - Digital temperature controller is an essential instrument in the field of electronics, instrumentation and control automation for measuring and controlling temperatures. it can be used as much at homes as in...__ Electronics Projects for You
Program converts temperature from RTD sensor - 06/05/97 EDN Design Ideas: 100V, platinum resistance-temperature-detector (RTD]sensor provide as an accurate means of obtaining temperature readings. Platinum sensors have a nonlinear resistance-vs-temperature characteristic; therefore, for Design by Robert Ruehle, Relco Products, Denver, CO
Quad Comparator Regulates Temperature - 10/26/95 EDN Design Ideas: Using a negative-temperature-coefficient thermistor, the circuit in Fig 1a controls temperature within 1°C or better with a minimum of components, cost, and complexity. The circuit includes protection against a short or open temperature sensor. You can purchase all of the key components, except the actual heating element, at the local Radio Shack. Design by H Randall Moore, Lake Forest, CA
Replace a Pushbutton Switch with this Infrared Safety Switch - Using a slotted optical sensor, this circuit can be used as a replacement for a large mushroom pushbutton safety switch . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2006
Resistor packs eliminate temperature drift - 06/19/97 EDN Design Ideas: Finding low-temperature-coefficient resistors for 10-bit or more accurate analog applications is often a problem in the laboratory. Even if you have a good collection of precision, low-temperature-coefficient resistors in stock, chances are they won't track across even room temperatures. Design by Jim Hansen, Kollsman Inc, Merrimack, NH
Resolving Very Small Temperature Differences with the LTC2402 - DN257 Design Notes__ Linear Technology/Analog Devices
Room heating controller - Tired of mechanical thermostats that overshoot the set point and make you waste expensive energy? Here is a phase-control device that works well and is simple! __ Designed by Manfred Mornhinweg
Self Powered Solar Box Furnace - This project involves the construction of a self contained solar box furnace (Photo 1). I assembled the prototype with materials that I had laying around my workshop. it is suitable for heating up a small room or a detached shed. I use the furnace to warm up my garage, it takes the chill out of a fairly large space when the weather is cold, but sunny. it is possible to scale this project up to any size, a larger version, or a set of them, could be used to add a lot of supplemental heat a house __ Designed by G. Forrest Cook
Simple Soldering Iron Temperature Regulator - Soldering irons are available in different wattage and usually run at 230V AC mains. However, these have no temperature control. Low-voltage soldering irons (e.g., 12V) generally form part of a soldering...__ Electronics Projects for You
Simple Circuit Microcontroller-Temperature Measurement Uses Only a Diode & a Capacitor - 12/05/08 EDN Design Ideas: Discharging a capacitor through the reverse leakage of a PN junction allows you to measure ambient temperature. Using a PN-junction diode for temperature measurement usually depends on its 2‑mV/K temperature coefficient. Conventionally, you must amplify and digitize this voltage with an ADC before you can use the value in a microcontroller. Less well-known is the fact that the reverse current of a PN-junction diode shows a good exponential dependency over temperature; increasing the temperature by approximately 12K doubles the leakage (Figure 1). An easy way to measure current over such a large range of two to three decades is to charge and discharge a capacitor and measure the time or frequency Design by Andreas Grun |