Ten Daily Electronic Common Sense-Section 10

Diode selection criteria in circuit design：

1. According to the selection of circuit function: a High-frequency detection circuit should use 锗 detection diode, which is characterized by high workpiece frequency, small forward voltage drop, and small junction capacitance, 2AP11~17 for 40M, 2AP9~10 for 100MHereinafter, 2AP1~8 is used for 150M or less, and 2AP30 is used for 400M or less.3. Reasonable selection of the diode according to the cost performance of the whole machine: According to the cost performance of the whole machine and the role of the matching diode in the whole machine, a reasonable selection is made. The junction type and the glass bulb diode should be prevented from falling on the hard ground.·
2. For the glass bulb diode, the soldering iron should be prevented from directly contacting the glass bulb during soldering.
3. The forward voltage cannot be applied to the Zener diode.
4. The base diode is susceptible to electrostatic damage, and the person and equipment should be grounded.·
5. For the chip diode, pay attention to the expansion of the diode itself and the printed board.
6. For diodes with matching requirements, it is necessary to prevent mixed groups during use, so as not to affect debugging.

Performance characteristics of the MAX134：

1. MAX134 adopts multiple integral A/D converters, and the maximum count value is usually plus or minus 39999. If the spare bit is dedicated for UP (DOD) automatic zero calibration, it is plus or minus 3999. It can also be increased to 79999 when measuring unipolar signals.
2. The A/D conversion accuracy is 0.025%, and the highest resolution is 5UV. When the clock frequency is 32768HZ, the measurement rate reaches 20 times/S. The chip includes an A/D converter, range switch, buzzer driver, active filter, battery low voltage detector, and has a completely digital interface, with BCD code output, and can achieve up to 20 functions after UP.
3. Adapt to 9031, 8051, and other microcontrollers. When forming a smart meter, MAX134 can provide all logic circuits, counters, and registers for A/D conversion, and complete the measurement through an additional mode selection circuit. The range and mode selection are set by UP, and the zero reading correction is also completed by UP.
4. With UP and AC/DC converter, the basic range is set to DCV (400MV, 4V, 40V, 400V, 4000V); ACV (same as DCV, but both are RMS); ACA (400MV RMS); ohms (400 ohms) , 4,000 ohms, 40,000 ohms, 400,000 ohms, 4 megohms); detect diodes; check circuit continuity (buzzer block). The range can be automatically converted when measuring voltage and resistance.
5. Powered by a 9V laminated battery or positive and negative 5V dual power supply, the working current is 100UA. In sleep mode, the quiescent current is only 25UA.

What are the main functions of the main control circuit?

• Receive various signals. The main control circuit mainly receives the following signals:·
  1. In the function preset stage, receiving preset signals for each function.
  2. Receive a given signal input from the keyboard or an external input terminal.
  3. Receive the control signal input from the external input terminal.
  4. Output calculation results.
• The calculation results of the main control circuit output are as follows:·
  1. The drive circuit output to the inverter causes the inverter device to output the SPWM voltage wave according to the given signal and the preset requirement.
  2. Output to the display to display the current status.
  3. Output to the external output terminal. Receive signals from voltage, a current sampling circuit, and other sensors (such as temperature sensor), combined with the limits in the preset function, for comparison and judgment.
• If it is considered that a fault has occurred, then:·
  1. stop sending SPWM signal to make the inverterAborting the output.
  2. Output an alarm signal to the output control terminal.

What constitutes a resonant accelerometer?

The resonant acceleration sensor is composed of a support beam, a mass, a resonator, an excitation unit, and a vibration pickup unit.

What is the watchdog timer?

The watchdog timer has a l5-bit counter. `

After the prescaler divides the CPU clock, the timer counts down the clock.By setting the PM1 bit of the PM1 register, it is possible to select whether to generate a watchdog timer interrupt request or a watchdog timer reset when the watchdog timer underflows.

When the main clock, internal oscillator clock, or PLL clock is selected as the CPU clock source, the prescaler can be selected to divide by 16 or divide by 128 through the WDC7 bit in the WDC register.

When the subclock is selected as the CPU clock source, regardless of the WDC7 bit, the prescaler is always divided by two.

What are the LED lighting products?

After Edison invented the carbon filament incandescent lamp in 1879, lighting technology entered a new era.`

Looking back on the history of lighting in the 20th century, new sources such as fluorescent, mercury, high and low pressure sodium, metal halide, compact fluorescent, high frequency electrodeless fluorescent, microwave sulfur lamps are emerging.

However, it is still LED that really causes the qualitative change of lighting technology.

What are the power saving modes?

1. Two ultra low power stop modes.
2. Wait for mode for reducing power consumption.
3. Ultra low power real-time clock interrupt, can operate in the run, wait and stop modes.

What is included in battery management technology?

• Charging: The types of secondary battery charging circuits and charging algorithms are various, and they are appropriately charged in a unique system environment for a specific chemical type of battery.
• Protection: When using lithium-ion/polymer batteries, protection must be provided because overcharging or overheating can cause fire or explosion.
• Fuel metering: Fuel metering is more than monitoring the current flowing into and out of the battery pack. Accurate fuel metering requires a systematic approach that takes into account typical usage patterns and environments.
• Safety: It is critical for lithium-ion battery pack manufacturers to build safe and reliable products for battery-powered systems.

What are the types of near field tag antenna structures?

Three near-field tag antenna structures: small loop antenna, ring-shaped cracked resonant antenna, and elongated loop antenna.

What is the data link layer?

A notable feature of the WirelessHART standard is its time-synchronized data link layer.The communication time slot of the Wire-lessHART data link layer is strictly defined as 10 ms and uses TDMA technology to support collision avoidance and deterministic communication.