38results about How to "Adjustable magnification" patented technology

The invention relates a method for detecting line insulation of a circuit board. According to the method, the insulating resistance of the circuit board is detected by adopting an insulating resistance testing circuit of the circuit board. The detection method comprises the following steps of: providing a compensating circuit which is connected with the compensating end of a front end circuit; and generating compensating voltage or current by using the compensating circuit to eliminate the error of output total voltage Uo of the front end circuit, wherein the error only refers to an error generated by the base current IB of a triode which is in a conducted state in a triode array flowing into a sampling resistor. According to the method, an amplifying circuit consists of multiple stages, and the amplifying time is adjustable and high; an error output quantity caused by the base current of the triode in the measuring circuit is compensated through the compensating circuit, and an error caused by the base current of the triode in the triode array is eliminated; and double-end differential mode input is adopted at the first stage of the amplifying circuit, and single-end output is adopted at the tail stage of the amplifying circuit, so that the amplifying circuit has the characteristics of high common-mode rejection capability, low null drift, high input impedance, low output impedance and the like.

The invention provides an earthquake forecasting instrument which comprises a base, a coil, an alternating current amplifier, a current-limiting gate and an alarm device, wherein the coil is vertically arranged above the base; the coil, the alternating current amplifier, the current-limiting gate and the alarm device are sequentially connected; an amplification factor of the alternating current amplifier can be adjusted; the alternating current amplifier is provided with discontinuous gears; and the current-limiting gate is structurally characterized in that the current-limiting gate is conducted when an input voltage is larger than a rated voltage and is cutoff when the input voltage is less than the rated voltage. The earthquake forecasting instrument can monitor earth magnetism abnormal fluctuation in the early stage of earthquakes, has simple structure and low cost, is free from environmental influence and is convenient for a person to carry and use.

The invention discloses a readout circuit of a current-type terahertz pyroelectric detector, which belongs to the field of terahertz detection and imaging. The readout circuit includes a current-voltage converter, a 50Hz trap circuit, a first-order low-pass filter amplifier circuit and a potential raising module. Among them, the signal output by the terahertz pyroelectric detector is input into the current-voltage converter, which is used to convert the current signal into a voltage signal; the signal output by the current-voltage converter is input into the 50Hz trap circuit, which is used to eliminate power frequency interference; The signal output by the 50Hz notch circuit is input into the first-order low-pass filter amplifier circuit for further signal amplification; the signal output by the first-order low-pass filter amplifier circuit is then input into the potential raising module, which is used to raise the voltage so that the voltage signal output by the circuit is consistent with the subsequent The terminal digital acquisition circuit needs to match the voltage. The voltage signal output by the readout circuit is pure, and is suitable for collecting and outputting the weak current of the terahertz pyroelectric detector.

The invention discloses a high-strength mining expansion filling fireproofing and extinguishing material and an application method thereof. The material comprises the following substances in parts by weight: 16-25 parts of aluminate cement clinker, 12-20 parts of Portland cement clinker, 4-16 parts of active calcic material, 6-15 parts of setting accelerator, 5-10 parts of quicklime, 22-40 parts of fly ash, 0.1-1 part of zinc powder foaming agent, 0.5-2 parts of thickening time control agent, 1-2 parts of aluminum hydroxide, 1-3 parts of dispersing agent and a proper amount of sodium hydroxide. By adding the sodium hydroxide, the pH value of the prepared slurry is 12-13. The material can obviously enhance the compression strength of the filled body, can enhance the critical fracture toughness and stability of the filled body, implements long-distance line delivery, and also implement quick filling and high-efficiency fireproofing and extinguishment.

The invention provides a bipolar PNP transistor and a manufacturing method thereof. The bipolar PNP transistor comprises a substrate, an epitaxial layer formed on the substrate, a deep phosphorus zone, a base zone, a collection zone and an emission zone which are formed in the epitaxial layer, a first interlayer dielectric layer and a voltage modulation dielectric layer which are formed on the epitaxial layer, a first interconnection line formed on the first interlayer dielectric layer and the voltage modulation dielectric layer, a second interlayer dielectric layer formed on the first interlayer dielectric layer and the first interconnection line, and a second interconnection line formed on the second interlayer dielectric layer, wherein the base zone is covered by the voltage modulation dielectric layer, and electric leading out is realized through the first interconnection line. According to the bipolar PNP transistor and the manufacturing method, through forming the voltage modulation dielectric layer on the base zone, the electric leading out of the voltage modulation dielectric layer is realized through the first interconnection line, so the charge concentration of a base zone surface is changed through changing the induction charge number of the voltage modulation dielectric layer, and thus the magnification times of small current is adjustable.

The invention discloses a detection and amplification device for micro current, comprising a sampling circuit, an MCU (Micro Control Unit) control circuit and an amplification circuit, wherein the MCU control circuit controls sampling voltage; the amplification circuit amplifies the sampling voltage output by the sampling circuit; a filtering amplitude limiting circuit is connected between the sampling circuit and the amplification circuit; the amplification circuit comprises a first amplification circuit and a second amplification circuit; the filtering amplitude limiting circuit comprises afirst filtering amplitude limiting circuit and a second filtering amplitude limiting circuit; the MCU control circuit controls the first path of sampling voltage output by the sampling circuit to be filtered by the first filtering amplitude limiting circuit, and the first path of sampling voltage is input into a first path of amplification circuit for amplifying; and the MCU control circuit controls the second path of sampling voltage output by the sampling circuit to be filtered by the second filtering amplitude limiting circuit, and then, the second path of sampling voltage is input to the second amplification circuit for amplifying. The detection and amplification device has the advantages of accurate sampling, adjustable amplification multiple, simple circuit, reasonable design, strong practicality, simplified use and operation and strong anti-interference performance, and is simple and easy to realize.