â–¡ Liu Yaosheng's homemade adjustable thermostat and timing electric oven, with the editor's comments. This oven is equipped with a thermocouple temperature sensor and features an adjustable thermostat and timing circuit for reference. The device can function both as a drying tool and as a home kitchen appliance. The oven circuit consists of a power supply, a thermocouple, an operational amplifier, a low-pass filter, a comparator, a temperature setting circuit, a control system, a timing mechanism, and a heating element.
The power supply circuit includes a transformer, a bridge rectifier, an integrated voltage regulator (1404), a 7812 voltage regulator, and capacitors, providing a stable 12V DC output to power the amplification, comparison, and control circuits. Port 1 is a current-limiting lamp with a resistor for safety.
The thermocouple used is a commonly available armored type, mounted in a shell. The signal from the thermocouple is small due to its low sensitivity, so it needs to be amplified. After amplification, the signal passes through a low-pass filter to reduce noise and improve stability.
The comparator circuit uses an open-loop configuration. It forms a voltage divider that feeds into the positive input terminal of the comparator. When the reference voltage is set properly, the output remains low, keeping the oscillator inactive and the alarm silent. However, if the signal changes, the comparator triggers the alarm.
When the grain flow is interrupted, the infrared light emitted by one tube may not reach the other, causing the signal to change. This causes the capacitor to charge, which eventually triggers the 555 timer, leading to an alarm. During testing, the system should be adjusted using a potentiometer to achieve optimal sensitivity.
During installation, the infrared emitter and receiver tubes must be aligned directly with the grain drop pipe. Other components are soldered onto a small circuit board. The infrared tubes used are 303 and 302 types, and the 555 IC is a standard model. Resistors are carbon film types with appropriate values marked on the diagram.
Another project is a computer voice karaoke machine developed at Shaoxing University of Arts and Science by Xu Yongwei. This device allows users to send custom messages or songs to friends via phone. When someone answers the call, a pre-recorded message plays, followed by music. It makes use of internal campus phone networks to provide free calls and enhance the user experience.
This karaoke machine is simple to build and cost-effective. It requires only a small circuit board and minor modifications to the phone. The modified phone is a Tsinghua Tongfang 031 Ding 501 dual-system caller ID phone. By connecting the microphone and receiver to the circuit board, the system becomes functional.
The control circuit includes a relay, a mechanical timer, a solid-state relay, and a heater indicator light. When the thermocouple signal exceeds the set temperature, the comparator turns off the heater, allowing the oven to cool. Once the temperature drops below the set point, the heater turns back on, maintaining a stable temperature.
The heater is installed in the upper and lower parts of the oven, with heat shields to prevent overheating. The circuit board includes a power switch, a timing knob, a temperature adjustment potentiometer, and a thermometer for calibration.
The editor's comment on Liu Yaosheng's self-made oven states that the design is feasible but has some flaws. The comparator circuit lacks hysteresis, causing frequent switching and potential damage to the relay. To fix this, a positive feedback resistor can be added to create a hysteresis effect, stabilizing the system and reducing unnecessary cycling.
Modern shave brushes are similar in appearance, composition and function to their centuries-old predecessors. Although a variety of different materials are still used to fashion shave brush handles, synthetic handles of nylon, urethane or plastic are the most common even with the most expensive shave brush manufacturers. Benefits of synthetic handles include a lesser chance of breakage and resistance to damage by moisture.
A shave brush's price is usually determined more by its bristle load than any other factor, except for brushes with very exotic handles. The most expensive brushes often use exotic materials in the handle. The bristles are fixed together into a knot that is installed into the handle. The best quality brushes are hand knotted. Badger and boar brushes are the most commonly found animals used for Shaving Brush fibers. Badger species include the Eurasian and the hog badger.
Badger brushes are often referred to as two band, or three band. Perhaps all badger hair fibers have three bands, but those used in the brushes conceal the lighter bottom band. Nonetheless, both types of bristle make desirable shaving brushes. Lower-quality brushes are often machine made and the bristles may be trimmed, resulting in sharp, prickly tips.
Best badger are brushes made with the finer and more pliable hairs from 20 - 25% of the badger's body. It is longer in length and lighter in color than 'pure' badger hair. A 'best' badger brush is more densely filled with hair than the 'pure' badger brush and will produce a correspondingly greater lather. However, some wet shavers argue that the variance between the quality of a 'pure' and a 'best' badger brush is negligible. Best badger and better quality brush hairs are often fit so that the ends do not have to be cut to shape.
Synthetic shave brushes, most often made using nylon bristles, are available in a range of prices and gradations in quality. Comparable to traditional shaving brushes, synthetic fiber brushes can quickly create a rich lather using relatively little shaving soap or cream. The synthetic fibers dry faster than natural hair and are less sensitive to everyday use.
Nylon Hair Shaving Brush,Shaving Brush Head,Beard Shaving Brush,Acrylic Shaving Brush Head
SAMINA FORAM (SHENZHEN) CO., LIMITED. , https://www.saminabrush.com