â–¡ Liu Yaosheng homemade adjustable thermostat timing electric copy box attached to the editor's comment period published type thermocouple temperature sensor homemade adjustable thermostat timing electric oven circuit for reference. The oven can be used both as a drying device and as a home kitchen appliance. Oven circuit 1. This circuit consists of a power supply type thermocouple operational amplifier low-pass filter comparator temperature setting circuit control and timing circuit and warmer.
1 power circuit consists of transformer D-rectifier bridge 1404 integrated voltage regulator circuit 7812 and capacitor, 102. The output DC voltage is 12 volts, providing operating voltage to the amplification comparison and control circuitry.
The port 1 is a power limiting lamp with a current limiting resistor.
Thermoelectric 1禹 selects the commonly used type of shell-mounted armored thermocouple, 2, temperature measurement and amplification and low-pass filter circuit. Because the sensitivity of the thermocouple is low, the generated signal voltage is small, and the signal needs to be amplified. The amplified open-ended shell-insulated low-pass filter is used to eliminate external disturbances and has better load carrying capacity.
4. The comparison circuit consists of the open loop working 3, which constitutes the voltage dividing circuit and goes to the 3 positive input terminal. Wzty, wMMwyrtje9iaa and conduction, the point is pulled down to low level, the oscillation circuit does not vibrate, and the speaker does not alarm.
When the pipe is blocked, the grain will not fall any more, so that the infrared light emitted by one pipe will always be irradiated or not always on, and the tube will always be low or high. Because it is a DC signal, it will no longer pass the capacitor, and 1 will reach the defect point, so the capacitor 02 starts to charge. Then, 3 also charges with the charging of 02. Soon, the voltage on the capacitor, 2, 3 will be charged. When reaching the flip voltage of 555, the 2 and 6 feet of 555 become high level, 555 resets the 3 pin output low level to make the pole tube 2 cut off, 0 point becomes high level, start the oscillation circuit, so that the speaker sounds alarm .
After the physical debugging and installation are connected according to the principle, close the power supply, first simulate the falling of the wheat grain by hand, and then put the hand between the 01 tube and the 02 tube, and do the up and down wave motion, so that the infrared light irradiated on the 02 tube is broken. When the time is passed, the speaker should not sound. Otherwise, the potentiometer can be properly adjusted to achieve the best sensitivity. Then the hand stops the swing and does not block the light. The analog pipeline is blocked and the speaker will sound. Report.
When installing the physical object, the most important point is the installation of the infrared pair tube, 1 and 02. It is necessary to install the two tubes directly opposite the wheat drop pipe, and it can be placed in the middle of the pipe according to the specific situation. As for other components, it can be soldered on a small circuit board, and then the seeding machine infrared light-emitting tube 0102 adopts the body-infrared infrared tube 3rd 303 and 302, the integrated block 555 adopts the commonly used 555, and the resistors all adopt low power. Carbon film resistance, its specific resistance and parameters of other components are marked in 1.
Practical electronic production campus production selection computer voice karaoke machine â–² Shaoxing University of Arts and Science Xu Yongwei When the other party picked up the microphone to answer the phone, the phone sent a warm and warm computer voice 05758345277 Hello, Mr. Lin on demand for the first ice rain hope You have a good mood every day! Then the music rings. The other party will be grateful to the friend for this special gift.
It is now fashionable to send songs to blessings. Click song but the cost is higher. The author developed a computer voice karaoke machine, the effect is quite good and simple to make, you can send songs to friends at any time to send blessings.
Many internal campus telephone networks have realized internal calls for free. This karaoke machine makes full use of this resource. It only needs to make a small circuit board and slightly change the telephone, and the circuit is attached. The modified telephone is Tsinghua Tongfang 031 Ding 501 dual-system caller ID telephone, which opens the phone and finds the connection line connected to the handle on the circuit board, which is the handle receiver and the handle microphone. Strip the insulation of the wire and solder the two 43.5 sockets to provide the reference voltage. Only set the potentiometer for the temperature, ie the reference voltage is given.
When the defect voltage is lower than the point voltage, 3 outputs a high level, otherwise 3 outputs a low level.
5. The control circuit consists of: 1 relay mechanical timer, 05 solid state relay heater working indicator light, when the thermoelectric potential generated by the thermocouple is amplified by six 1 to make the signal voltage of the defect point higher than the preset oven temperature signal point voltage, 3 output low level, cut off, relay release, 02 does not light, solid state relay cut off the heater power supply to stop heating. At this time, the temperature of the oven no longer rises, and the heat diffusion causes the temperature in the oven to drop, and the thermoelectric potential generated by the type thermocouple decreases. When the amplified thermoelectric potential signal voltage is lower than the point voltage, 3 outputs a high level, 1 It is turned on, the relay is closed, and the day 02 is lit. At the same time, the solid state relay turns on the heater power supply, the heater works, and the temperature in the oven starts to rise again, thereby achieving constant temperature control.
After the production of the constant temperature electric oven 3.
The heater selects the appropriate power according to the maximum temperature to be reached by the oven, and can be installed in the upper and lower parts respectively. The board is fixed to the right and isolated by a heat shield.
Timing knob temperature knob, circuit board power switch mechanical timer temperature setting potentiometer RP is installed in the front right side knob knob temperature setting finger marking line, marked with a thermometer after the actual measurement.
Editor's comment on Mr. Liu Yaosheng's self-made adjustable constant temperature timing oven, the circuit design is feasible, and should work properly. But the circuit design is a bit flawed, ask the design of the comparator 3 = here 3 is designed as a simple comparator, its transfer characteristics as long as the oven reaches and slightly exceeds the temperature, 7 and 8 divided pressure set the temperature 1 line on the abscissa The corresponding temperature value on the six heaters immediately powers off and stops heating; when the temperature of the oven drops slightly and is lower than the set temperature, the heater is immediately energized and heated, causing the heater to frequently move around the temperature set point, causing the electric wire relay, etc. The impact is even damaged.
Inflow into 8 ports makes the temperature setting voltage of the point slightly larger than the original value. When the oven temperature exceeds this set value corresponding to 4 points on the 3 abscissa, 3 outputs a low level, and the heating wire is powered off to stop heating. . Since the 3 output goes low, at this time 12, the power supply passes through, and after 7 is flowing, the improvement method is very simple, as long as the resistance of the 6-3 simple comparator circuit is increased, only the resistance latch 2 becomes hysteretic comparison. The device is solved, and the transfer characteristic of the hysteresis comparator is 3. When the output of the high level is 3, the heating wire is energized and heated, because there is a feedback current from the 3 output terminal, the newly added positive feedback resistor sets the voltage. The value is lower than when the heating wire is energized, and the degree of the oven is reduced to a point higher than 3 until it is low. After the point, 3 can output a high level again to heat the heating wire. This temperature interval is determined by the resistance of the latch. The larger the latch relative to the latch, the smaller the hysteresis of the hysteresis comparator is, as long as there is a small
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