 Exothermic circuit
I am using the nichrome wire to have the generation of heat. Because the length of the exothermic part this time is about 30 cm, the nichrome wire which was rolled up in coil-shape suits. The nichrome wire which I used this time is the 300-W one in AC 100 V. It becomes hot when connecting AC 100 V with direct. To make the about 160°C temperature like this time, it is necessary to control the electric power.
Electric power control
With the circuit this time, I controlled to become the temperature which was set by detecting the temperature of the exothermic part. I think that it is not in the problem even if it controls the electric power only with the variable resistor without making be connected with the temperature detecting element. I think that the thermometer is necessary in the case to know the how much temperature the exothermic part becomes.
Thermometer
I used the thermometer of the diode sensor, but it is possible to use if being the thermometer which it is possible to measure in about 150°C. The thermometer which it is possible to measure in about 150-200°C with the small thermometer is marketed. I think that it is good to use it, too. However, in case of the such thermometer, there are many ones to work with the cell. May be troublesome a little.
Power circuit
The power supply switch to put to the equipment is put in the nichrome wire circuit. Therefore, the power supply of the thermometer or the temperature controller isn't switched off at the power supply switch.
The temperature of the exothermic part doesn't fall suddenly even if the bend work ends and the power supply is switched off. So, the temperature of the exothermic part must be watched over with the thermometer after the power supply switch is cut and the power supply supply to the exothermic part is made to stop, too.
In this condition, the power supply to the temperature controller is unnecessary. However, because the power supply is common, the power supply is supplied. Because the electricity consumption of the temperature controller is small, there is no problem.
The power supply voltage of ICL7136 to be using with the thermometer is OK to +15 V. However, I lower the voltage with the resistor to make +9 V which are the recommendation voltage of the circuit.
If pulling out the AC cord from the outlet, the thermometer stops.
When making the power supply switch OFF, the power supply to the nichrome wire stops. However, because the power supply to the temperature controller is supplied, the LED lights up, being red when the temperature of the exothermic part falls. The LED which lights up, being red shows that the power supply is supplied to the nichrome wire. This has the possibility to mistake. Therefore, I make light up the neon lamp when the power supply switch is ON. When the neon lamp lights up and the LED is the red, it is in the condition that the power supply is supplied to the nichrome wire. When the neon lamp goes out, even if the LED lights up, being red, the power supply is in the condition which isn't supplied to the nichrome wire. (The explanation is complicated a little)
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