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Temperature Control Circuits

Temperature Controls:  #'s - F       G - S       T - Z
 

Last Updated: October 24, 2017 02:55 PM

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Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

Temperature Alarm -  A simple op-amp circuit that will trigger a relay when a preset temperature is reached.  Please note that there is no hysteresis in this circuit, so that if the temperature changes rapidly, then the relay may switch rapidly.   __ Designed by Andy Collison

Temperature Controled Fan -  This circuit controls very accurately a fan of any size.    Just adjust the associated resistors for a different type and you're all set.    The above circuit diagram is for a small cpu-fan, rated 12V at 12mA current.   __ Designed by Tony van Roon  VA3AVR

Temperature Controlled NiCad Charger -  This circuit is for a temperature controlled constant current battery charger.  it works with NIC D, NiMH
, and other rechargeable cells.  The circuit works on the principle that most rechargeable batteries show an increase in temperature when the cells becomes fully charged.  Overcharging is one of the main causes of short cell life, hot cells pop their internal seals and vent out electrolyte.  As cells dry out, they lose capacity.  This circuit can quickly charge a rechargeable battery pack without any negative effects.  This circuit uses a 22VDC power supply, my version 2 circuit will run from a 12VDC supply such as a solar-powered or automobile power system. __ Designed by G. Forrest Cook

Temperature Controlled Ovens -  Here is a simple temperature controller suitable for a variety of purposes; it was designed to heat the copper float out of a toilet for a barometer!  __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

Temperature Controller -  The LM3911 requires only a few resistors and capacitors to turn it into a full-function temperature controller.    The schematic diagram illustrates the simplicity of the overall circuit.    The resistor network consisting of R1, R2, and R3 are used to provide the set point voltage for the feedback input of the LM3911 __ Designed by Tony van Roon  VA3AVR

Temperature controller has "take-back-half" convergence algorithm -  09/15/05 EDN Design Ideas:  Enhanced closed-loop control balances stability, responsiveness __ Circuit Design by W Stephen Woodward, University of North Carolina, Chapel Hill, NC

Temperature controller keeps IR Detector at 8ºK -  01/07/99 EDN Design Ideas:  Sensitive infrared array detectors must operate at a low temperature to avoid thermally generated dark current throughout the photoconductive elements.  This requirement is particularly true for SiAs array detectors, which   Page includes several designs.  Scroll to find this one __ Circuit Design by Jerry Penegor, Space Sciences Laboratory, University of California—Berkeley

Temperature controller saves energy -  3-Feb-05 EDN Design Ideas:  Given the high cost of electrical power, replacing a conventional on/off temperature control with a proportional controller can often save energy and money.  Figure 1 shows a low-cost, high-efficiency, time-proportional temperature controller for a residential water heater.  An Analog Devices ADT14, IC 1, serves multiple functions as a temperature sensor, quad-setpoint, programmable analog tempe __ Circuit Design by Tito Smailagich, ENIC, Belgrade, Yugoslavia

Temperature Data Logger -  This project will show you how to build Temperature Logger using a Stamp iI connected to a PC serial port.  I was planing on using the DS1620, but used a LM335 temperature sensor because it only needs a two wire interface and it is easy to waterproof.  All I did to waterproof it was to put some heat srink tubing around the 3 wires then around the hole sensor __ Designed by shaunwilson19 @ yahoo.com

Temperature Logger for the Fridge -    NOTE: Must register on this site __ Designed by Published in Elecktor July/Aug, 2010

Temperature Monitor & fan controller reduce fan noise -  01-May-01 EDN Design Ideas:  The scheme in Figure 1 reduces system acoustic noise by running system fans at their optimum speeds for a given temperature.  IC 1  combines ±1°C-accurate temperature measurement of three temperatures with automatic fan-speed control of two channels.  A two-wire serial interface allows you to oversee critical temperature and fan-speed data __ Circuit Design by David Hanrahan, Analog Devices Inc, Limerick, Ireland

Temperature Monitor measures three thermal zones -  12/11/03 EDN Design Ideas:  You can use an ADT7461 single-channel temperature monitor; an ADG708 low-voltage, low-leakage CMOS 8-to-1 multiplexer; and three standard 2N3906 pnp transistors to measure the temperature of three separate remote thermal zones (Figure 1).  Multiplexers have resistance, RON, associated with them; the channel matching and flatness of this resistance normally result in a varying temperature offset.  This system uses the ADT7461 temperature monitor, which can automatically cancel resistances in series with the external temperature sensors, allowing its use as a multichannel temperature monitor.   __ Circuit Design by Susan Pratt, Analog Devices, Limerick, Ireland

Temperature Monitor using 741 opamp -  A simple op-amp circuit that will trigger a relay when a preset temperature is reached.  Please note that there is no hysteresis in this circuit, so that if the temperature changes rapidly, then the relay may switch rapidly.   __ Designed by Andy Collison

Temperature Monitor with Alarm -  This temperature monitor alarm circuit continuosly monitors the room temperature and beeps when the temperature drops below 20 degrees centigrade.  This capability to constantly monitor the room temperature can help lower your air-conditioning costs by reminding you to turn off your airconditioner.  An optical display like a __ Designed by Popescu Marian

Temperature Programmer Uses Digital Control -  07/18/96 EDN Design Ideas:  The circuit in Fig.1 is useful for precise, repetitive temperature control of small-volume objects.  it offers high resolution and effective isolation between the control lines and the power mains.  it generates no RFi, has adequate speed, and provide as a linear relationship between the digital-input code and the average thermal power supplied by the heater.  The circuit works by generating a programmable number of triggering pulses to a TRIAC connected in series with the heater __ Circuit Design by Jordan Dimitrov, N Poushkarov Institute of Soil Science and Agroecology, Sofia, Bulgaria

Temperature Recorder. Part 1 -  This project uses a Microchip PIC  microcontroller, a serial EEPROM and a thermistor to create a temperature recorder.  Performance The temperature is measured and stored at user programmable intervals; this can be from 1 __ Designed by Andrew M. Bishop

Temperature Recorder. Part 2 -  Software PIC  Software The PIC  software is written in assembler and based on earlier projects using I 2 C interfaces.  The EEPROM, PIC  and external connector all share the same I 2 C bus and the PIC  will not use it unless the thermistor is fitted.  __ 

Temperature-Measurement Scheme Uses IR Sensor & Sigma-Delta ADC -  3-Apr-03 EDN Design Ideas:  Many noncontact temperature-measurement systems use infrared sensors, such as thermopiles, which can detect small amounts of heat radiation.  Biomedical thermometers that measure the temperature of an ear or a temple use noncontact temperature measurement, as do automotive-HVAC systems that adjust temperature zones based on the body temperature of passengers __ Circuit Design by Albert O'Grady and Mary McCarthy, Analog Devices, Limerick, Ireland

Thermal Cooling Fan Controller -  As we begin to enjoy those lazy hazy days of summer, the most important thing on most of our minds is how to keep cool during those hot days.  For some of us that means turning up the old air conditioner and sipping on a nice cold glass of our favorite soft drink.  However, we often forget about an equally important __ Designed by Radio Amateur Society of Norwich

Thermo Alarm -  The Th1 thermistor is a regular NTC (Negative Temperature Coeficient) of about 1000 ohms.    But other types will work too.    Adjust the sensitivity with the 20K trim-pot P1.  When the thermistor is at operating temperature, the resistance is high The 330K resistor (R3) is to introduce a little bit hysteresis back on the basis of Q2 to prevent relay chatter __ Designed by Tony van Roon  VA3AVR

Thermofan to Keep Your Amp Cool -  Use a 12V computer fan to cool your amp.    Uses diode temperature sensor f __ Designed by Rod Elliott  ESP

Thermostat  (1N4148) -  Temperature controlled fan with diode temp sensor.  This circuit controls very accurately a fan of any size.  Just adjust the associated resistors for a different type like the R6 resistor of 100 ohm, 2 watt type and you’re all set.  The above circuit diagram is for a small 12 volt fan, the size and type determined by the user. __ Designed by Tonny Von Roon

Thermostat (NTC) -  The LM3911 requires only a few resistors and capacitors to turn it into a full-function temperature controller.    The schematic diagram illustrates the simplicity of the overall circuit.    The resistor network consisting of R1, R2, and R3 are used to provide the set point voltage for the feedback input of the LM3911 __ Designed by Tony van Roon  VA3AVR

Thermostat Control for Electric Heaters -  One Advantage of these two units is the Sensor can be placed Away from the heater, therefore sensing the Actual Room temperature, not the direct heat from the heater.  These can also be used in a confined space with a Heat Lamp, to create a Drying Oven  __ Designed by G.L. Chemelec

Thermostat for 1KW Space Heater SCR controlled -  Below is a thermostat circuit I recently built to control a 1300 watt space heater.  The heater element (not shown) is connected in series with two back to back 16 amp SCRs (not shown) which are controlled with a small pulse transformer.  The pulse transformer has 3 identical windings, two of which are used to supply trigger pulses to the SCRs, and the third winding is connected to a PNP transistor pair that alternately supply pulses to the transformer at the beginning of each AC half cycle.  The trigger pulses are applied to both SCRs near the beginning of each AC half cycle but only one conducts depending on the AC polarity. __ Designed by Bill Bowden

Two Temperature Controlled Relays -  Switching Circuits:  These two circuits use Thermistors (Temperature Dependent Resistors).  Circuit No.1 energizes the relay when the temperature rises above a preset level. Use it to switch things on when it gets hot. Circuit No.2 energizes the relay when the temperature falls below a preset level. Use it to switch things on when it gets cold.  __ Designed by Ron J.

Universal Compensator Neutralizes Temperature Coefficient -  05/25/95 EDN Design Ideas:  The universal thermal-compensation module in Fig 1  can neutralize the temperature coefficient of both signs within a �0.6%/�C range.  The circuit can compensate the temperature coefficient of offset voltage, gain, sensitivity, or, in general, the linear terms of a device's overall temperature behavior.  The circuit consists of a pair of negative-temperature-coefficient (NTC) thermistors, labeled RT, and of fixed resistors with calculated values that reduce the inherent nonlinearity of the thermistors __ Circuit Design by Alexander Belousov,  Standard Motor Products, Long Island City, NY

Use a Transistor as a Heater -  04/19/12  EDN Design Ideas:  A temperature sensor and a hot transistor hold biological samples at a preset temperature.  it is common to use transistors for driving resistive heating elements.  However, you can use the heat that a power transistor dissipates to advantage in several situations, eliminating the need for a separate heating element because most transistors can safely operate at temperatures as high as 100°C.  A typical example is in a biological laboratory, in which the need for maintaining the temperature of samples in microliter-sized cuvettes is a common requirement.   __ Circuit Design by REC Johnson, B Lora Narayana, and Devender Sundi, Center for Cellular and Molecular Biology, Hyderabad, India

Use Thermoelectric Coolers with Real-World Heat Sinks -  04/17/08  EDN Design Ideas:  When using a Peltier thermoelectric cooler with a less-than-perfect heat sink, you must derate the maximum voltage and current applied to the cooler __ Circuit Design by W Stephen Woodward, Chapel Hill, NC


Temperature Controls:  #'s - F       G - S       T - Z

 


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