Saturday, 14 January 2017
High temperature protector with IC 3584
IC 3584 has thermal protection or voltage automatically shutdown when the temperature at IC exceed 150 degrees or more. You can operate this circuit at the transistor or IC heatsing, if a transistor or IC had exceeded the limit of the heat circuit automatically shutdown.How to use a thermal shutdown circuit above that is first given a circuit of voltage V+,V-,and ground , the given a voltage Vin to be created automatically shutdown if the temperature is high , and the output is inserted in the circuit of an amplifier or other. Then IC embedded in the heatsing or case, which if too hot will shutdown alone. If the circuit already decided voltage, the voltage will re-connect if the temperature returns to normal.
Saturday, 7 January 2017
Temperature Controlled Soldering Iron
A soldering iron that’s ideally suited for use with this controller is available from Dick Smith Electronics (Cat T-2100). This circuit runs from a 12V battery or a mains-operated DC source. It works as follows: a DC-DC converter (IC1, Q1, D1, Q2, T1, D2, L1, etc) steps up the 12V DC input to about 16V. The higher voltage boosts the power to the iron and reduces warm-up time. This output voltage is applied to a resistance bridge in which the heating element of the iron forms one leg.
A degree of hysteresis built into the circuit makes the LED flicker between red and green while the iron is maintained at its preset temperature. Calibrate the circuit as follows: while the iron is still relatively cold, monitor the input voltage and current and adjust VR1 so that the input power (Volts x Amps) is about 50W. When you have done that, set VR4 to maximum and adjust VR2 so that the LED flickers between red and green when the iron has reached the desired maximum temperature.
Finally, set VR4 to mid-position and adjust VR3 so that the LED flickers when the iron reaches the desired mid-range operating temperature. As an example, you might choose to set the maximum temperature to about 400°C and the mid-range operating temperature to about 350°C. The overall temperature range, in that case, should be approximately 280°C to 400°C. Check that the calibration is correct and repeat the adjustment procedure if necessary. Use a temperature probe, preferably one designed especially for soldering irons, rather than guesswork, when making the adjustment.
- VR4 should have a logarithmic taper to compensate for non-linearity in the temperature-resistance characteristic of the soldering iron.
Friday, 16 December 2016
Oil Temperature Gauge for 125 cc Scooter
Lots of Far-Eastern scooters are fitted with GY6 engines. These already elderly units are sturdy and economical, but if you want to “push” the power a bit (so called ‘Racing’ kits, better handling of the advance, etc.), you soon find yourself faced with the problem of the engine temperature, and it becomes essential to f it a heat sink (of ten wrongly referred to as a ‘radiator’) on the oil circuit. Even so, in these circumstances, it’s more than reassuring for the user to have a constant clear indication of the oil temperature. Here are the specifications we set for the temperature gauge we wanted to build:
Oil Temperature Gauge Circuit Diagram :
- no moving parts (so not meter movement), as scooters vibrate a lot!;
- as cheap as possible (around £12);
- robust measuring transducer (avoid NTC thermistors and other ‘exotic’ sensors);
- temperature range 50–140 °C. (122 – 291 °F);
- audible and visual warning in case of dangerous temperature;
- compact;
- waterproof.
Let’s start by the sensor. This is a type-K thermocouple, as regularly used by multimeter manufacturers. Readily available and fairly cheap, these are robust and have excellent linearity over the measurement range we’re interested in here. The range extends from 2 mV to 5.7 mV for ten measurement points. The positive output from the thermocouple is applied to the non-inverting input of IC3.A, wired as a non-inverting amplifier. Its gain of 221 is determined by R1 and R2. IC3 is an LM358, chosen for its favourable characteristics when run from a single-rail supply. IC3.B is wired as a follower, just to avoid leaving it powered with its pins floating.
IC3.B output is connected to pin 5 of IC1, an LM3914. This very common IC is an LED display driver. We can choose ‘point’ or ‘bar’ mode operation, according to how pin 9 is connected. Connected as here to the + rail, the display will be in ‘bar’ mode. Pin 8, connected to ground, sets the full scale to 1.25 V. R3 sets the average LED current. Pin 4, via the potential divider R7/R8+R9, sets the offset to 0.35 V. Using R8 and R9 in series like this avoids the need for precision resistors.
As per the LM3914 application sheet , R4-R5-R6 and C5 will make the whole display flash as soon as D10 lights (130 °C = 226 °F). Simultaneously, via R10 and T1, the (active) sounder will warn the user of overheating. Capacitor C6 avoids undesirable variations in the reference voltage in ‘flashing’ mode. IC2 is a conventional 7808 regulator and C1– C4 filter the supply rails. Do not leave these out! D1 protects the circuit against reverse polarity.
The author has designed two PCBs to be fit-ted as a ‘sandwich’ (CAD file downloadable from [1]). In the download you’ll also find a document with a few photos of the project. You’ll note the ultimate weapon in on-board electronics: hot-melt glue. Better than epoxy (undoable!) and quite effective against vibration.
Author : Georges Treels - Copyright : Elektor
Monday, 28 November 2016
Temperature Detector For Fan Controller
If the fans should fail, for example, the maximum temperature limit would lie at a considerably higher level than the desired value. The accompanying circuit, which compares the magnitude of the fan voltage to a fixed reference value, has been developed to allow the maximum temperature to be reliably detected. This circuit is tailored for 12-V fans. The reference voltage is generated by the ‘micro power voltage reference’ D1 and the FET T1, which is wired as a current source. These components are powered directly from the applied fan voltage. The current source is set up to deliver approximately 50µA.
D1 can work with as little as 10µA. The supply voltage for the IC is decoupled by R10, C3 and C4, with D4 providing over voltage protection. A maximum supply voltage of 16 V is specified for the TLC271. This opamp works with a supply voltage as low as 3 V and can handle a common-mode voltage up to approximately 1.5 V less than the positive supply voltage. Accordingly, 1.2 V has been chosen for the reference voltage. The fan voltage is reduced to the level of the reference voltage by the voltage divider R2–R3–P1. The limits now lie at 11.2 V and 16.7V.
If you find these values too high, you can reduce R2 to 100 kΩ, which will shift the limits to 9.5 V and 14.2 V. The output of the voltage divider is well decoupled by C2. A relatively large time constant was selected here to prevent the circuit from reacting too quickly, and to hold the output active for a bit longer after the comparator switches states. A small amount of hysteresis (around 1 mV) is added by R4 and R5, to prevent instability when the comparator switches. D2 ensures that the magnitude of the hysteresis is independent of the supply voltage. Two outputs have been provided to make the circuit more versatile.
Output ‘R’ is intended to directly drive the LED of an optocoupler. In addition, transistor T2 is switched on by the output of the opamp via R7 and R8, so that a relay can be actuated or a protection circuit triggered using the ‘T’ output. The high-efficiency LED D3 indicates that IC1 has switched. It can be used as a new ‘maximum’ temperature’ indicator when this circuit is added to the fan controller. The circuit draws only 0.25 mA when the LED is out, and the measured no-load current consumption (with a 12.5V supply voltage) is 2.7 mA when the LED is on.Resistors:
- R1 = 22kΩ
- R2 = 120kΩ
- R3 = 10kΩ
- R4,R6 = 1kΩ
- R5 = 1MΩ
- R7,R8 = 47kΩ
- R9 = 3kΩ9
- R10 = 100Ω
- P1 = 5kΩ preset
- C1,C3 = 100nF
- C2 = 100µF 25V radial
- C4 = 47µF 25V radial
- D1 = LM385-1.2
- D2 = BAT85
- D3 = high-efficiency-LED
- D4 = zener diode 16V/1W3
- T1 = BF245A
- T2 = BC547B
- IC1 = TLC271CP
- K1 = 2-way PCB terminal block, raster 5mm
- K2 = 3- way PCB terminal block, raster 5mm
Tuesday, 15 November 2016
Electronic Temperature Controlled Relay
This temperature controlled relay circuit is a simple yet highly accurate thermal control circuit which can be used in applications where automatic temperature control is needed. The circuit switches a miniature relay ON or OFF according to the temperature detected by the single chip temperature sensor LM35DZ.
When the LM35DZ detects a temperature higher than the preset level (set by VR1), the relay is actuated. When the temperature falls below the preset temperature, relay is de-energized. The circuit can be powered by any DC 12V supply or battery (100mA min.)
Electronic Temperature-Controlled Relay Schematic
How it works?
The heart of the circuit is the LM35DZ temperature sensor which is factory-calibrated in the Celsius (or Centigrade) scale with a linear Degree->Volt conversion function. The output voltage (at pin 2) changes linearly with temperature from 0V (0oC) to 1000mV (100oC).
The preset (VR1) & resistor (R3) from a variable voltage divider which sets a reference voltage (Vref) form 0V ~ 1.62V. The op-amp (A2) buffers the reference voltage so as to avoid loading the divider network (VR1 & R3). The comparator (A1) compares the reference voltage Vref (set by VR1) with the output voltage of LM35DZ and decides whether to energize or de-energize the relay (LED1 ON or OFF respectively).
Components list:
IC1 : LM35DZ
IC2 : TL431
IC3 : LM358
LED1 – 3mm or 5mm LED
Q1 – General purpose PNP transistor ( A1015,…) with E-C-B pin-out)
D1, D2 — 1N4148
D3, D4 — 1N400x (x=2,,,,.7)
ZD1 — Zener diode, 13V, 400mW
Preset (trim pot) : 2.2K (Temperature set point)
R1 – 10K
R2 – 4.7M
R3 – 1.2K
R4 – 1K
R5 – 1K
R6 – 33Ω
C1 – 0.1 µF ceramic or mylar cap
C2 – 470 µF or 680 µF electrolytic cap. (16V min)
Miniature relay – DC12V DPDT, Coil = 400 Ω or higher
Monday, 14 November 2016
Temperature Regulator with TIP122 Circuit Diagram
Temperature Regulator Circuit with TIP122
This is fine in Cryocam Roy, but I’m afraid that many of our camera cookbook may not be able to reach a maximum temperature of Roy. That and the fact that related to the Zener 4.7V difficult to replace me with Roy Z 5.1V zener with more accessible. This diode is available off the shelf at Radio Shack. I supply the resistor network on a range of 190 K to 270 K or -83 C to -3 C I believe that most of our cameras can be maintained to -3 C and I doubt that all our cameras in a position are to be attained – 83 C, so I think that this area should be good enough coverage. I chose to use a 100k pot at some point, because I’m going to the plate with a dual digital potentiometer DS1267 replace. I do not allow for a distance, using Win245 software controllable temperature control and the 100K pot is the control loop is working is to be updated very easily. I intend to use the pot on the remaining DS1267 to replace R43 on the board pre-amp. This allows a selectable gain control software for the camera cookbook. More later.
I would recommend the maximum TEC voltage regulator and leave it there. The circuit temperature controller does the rest. You may want to perform delete on the part of the adjustment of supply voltage and tie the totally positive TEC voltage directly at the outlet of the resistors R1 and R2 in parallel with power supply stocks cookbook. There is much room is available for experiment. Roy says that his power TEC does not need to precisely controlled tension, but also be filtered and have less than 10% ripple. So, I think you no harm by not following the proportion of the supply voltage regulation will do Peltier.