Ammeters are devices that are used to determine the current strength in a circuit. Digital modifications are made on the basis of comparators. They differ in terms of measurement accuracy. It is also important to note that the devices can be installed in a circuit with direct and alternating current.
According to the type of construction, panel, portable, and built-in modifications are distinguished. By appointment, there are pulse and phase-sensitive devices. Selective models are allocated in a separate category. In order to delve into the instruments in more detail, it is important to know the device of the ammeter.
Ammeter circuit
A typical digital ammeter circuit includes a comparator along with resistors. A microcontroller is used to convert the voltage. Most often it is used with reference diodes. Stabilizers are installed only in selective modifications. Broadband filters are used to increase the measurement accuracy. Phase devices are equipped with transceivers.
DIY model
Collect digitaldo-it-yourself ammeter is quite difficult. First of all, this will require a high-quality comparator. The sensitivity parameter should be at least 2.2 microns. It must maintain a minimum resolution of 1 mA. The microcontroller in the device is installed with reference diodes. The indication system is connected to it through a filter. Next, to assemble a digital ammeter with your own hands, you need to install resistors.
Most often they are selected as a switched type. The shunt in this case should be located after the comparator. The division factor of the device depends on the transceiver. If we talk about a simple model, then it is used as a dynamic type. Modern devices are equipped with ultra-precise analogues. A regular lithium-ion battery can serve as a stable current source.
DC Devices
Digital DC ammeter is produced on the basis of highly sensitive comparators. It is also important to note that stabilizers are installed in the devices. Resistors are only suitable for the switched type. The microcontroller in this case is installed with reference diodes. If we talk about parameters, then the minimum resolution of devices is 1 mA.
AC modifications
Ammeter (digital) AC can be made by yourself. Microcontrollers in models are used with rectifiers. Broadband type filters are used to increase the measurement accuracy. The shunt resistance in this case should not be less than 2 ohms. The sensitivity of the resistors must be 3 microns. Stabilizers are most often installed expansion type. It is also important to note that you will need a triode for assembly. It must be soldered directly to the comparator. The permissible error of devices of this type fluctuates around 0.2%.
Pulse measuring instruments
Pulse modifications are distinguished by the presence of counters. Modern models are produced on the basis of three-digit devices. Resistors are used only orthogonal type. As a rule, the division factor for them is 0.8. The allowable error, in turn, is 0.2%. The disadvantages of the devices include sensitivity to the humidity of the environment. They should also not be used in sub-zero temperatures. It is problematic to assemble the modification on your own. Transceivers in models are used only dynamic type.
Phase sensitive modification device
Phase-sensitive models are sold at 10 and 12 V. The error tolerance for models varies around 0.2%. Counters in devices are used only two-digit type. Microcontrollers are used with rectifiers. Ammeters of this type are not afraid of high humidity. Some modifications have amplifiers. If you are assembling the device, you will need switched resistors. A conventional lithium-ion battery can act as a stable current source. The diode is not needed in this case.
Before installing the microcontroller, it is important to solder the filter. A converter for lithium-ion will need a variable type. His sensitivity scoreis at the level of 4.5 microns. With a sharp drop in voltage in the circuit, it is necessary to check the resistors. The division factor in this case depends on the bandwidth of the comparator. The minimum pressure of devices of this type does not exceed 45 kPa. The current conversion process itself takes about 230 ms. The clock rate depends on the quality of the counter.
Scheme of selective devices
The DC selective digital ammeter is based on high bandwidth comparators. The allowable error of the models is 0.3%. The devices operate on the principle of one-stage integration. Counters are used only two-digit type. Stable current sources are installed behind the comparator.
Resistors are used of the switched type. For self-assembly of the model, two transceivers are required. Filters in this case can significantly improve the accuracy of measurements. The minimum pressure of the devices lies in the region of 23 kPa. A sharp drop in voltage is quite rare. The shunt resistance, as a rule, does not exceed 2 ohms. The current measuring frequency depends on the operation of the comparator.
Universal Measuring Instruments
Universal measuring instruments are more suitable for domestic use. Comparators in devices are often set to low sensitivity. Thus, the allowable error lies in the region of 0.5%. Counters are used three-digit type. Resistors are used on the basis of capacitors. Triodes are found as a phase,and pulse type.
The maximum resolution of devices does not exceed 12 mA. The shunt resistance is usually around 3 ohms. Permissible humidity for devices is 7%. The limiting pressure in this case depends on the installed protection system.
Shield models
Shield modifications are made for 10 and 15 V. Comparators in devices are installed with rectifiers. The allowable error of the devices is at least 0.4 5. The minimum pressure of the devices is about 10 kPa. Converters are used mainly of variable type. For self-assembly of the device, you can not do without a two-digit counter. Resistors in this case are installed with stabilizers.
Integrated modifications
Digital built-in ammeter is produced on the basis of reference comparators. The throughput of the models is quite high, and the margin of error is about 0.2%. The minimum resolution of the devices does not exceed 2 mA. Stabilizers are used both expansion and impulse type. Resistors are set to high sensitivity. Microcontrollers are often used without rectifiers. On average, the current conversion process does not exceed 140 ms.
DMK models
Digital ammeters and voltmeters of this company are in great demand. In the assortment of this company there are many stationary models. If we consider voltmeters, then they can withstand a maximum pressure of 35 kPa. ATin this case, the transistors are of the toroidal type.
Microcontrollers are usually installed with converters. For laboratory research, devices of this type are ideal. The company's digital ammeters and voltmeters are manufactured with rugged housings.
Torex device
The specified ammeter (digital) is produced with increased current conductivity. The maximum pressure the device can withstand is 80 kPa. The minimum allowable temperature of the ammeter is -10 degrees. The specified measuring device is not afraid of the increased humidity. It is recommended to install it near the power source. The division factor is only 0.8. The ammeter (digital) withstands maximum pressure of 12 kPa. The current consumption of the device is about 0.6 A. The triode is of the phase type. This modification is suitable for home use.
Lovat device
The indicated ammeter (digital) is made on the basis of a two-digit counter. The current conductivity of the model is only 2.2 microns. However, it is important to note the high sensitivity of the comparator. The display system is simple, and it is very comfortable to use the device. The resistors in this ammeter (digital) are switched type.
It is also important to note that they are able to withstand a large load. The shunt resistance in this case does not exceed 3 ohms. The current conversion process is quite fast. A sharp drop in voltage can only be associated with a violation of the temperature regime of the device. Permissible humidity of the specifiedammeter equals as much as 70%. In turn, the maximum resolution is 10 mA.
DigiTOP Model
This DC digital voltmeter/ammeter comes with reference diodes. The counter in it is provided for a two-digit type. The conductivity of the comparator is at around 3.5 microns. The microcontroller is used with a rectifier. Its current sensitivity is quite high. The power source is a regular battery.
Resistors are used in a switched type device. The stabilizer is not provided in this case. There is only one triode. Direct current conversion occurs quite quickly. For domestic use, this device is suitable. Filters are provided to increase measurement accuracy.
If we talk about the parameters of the voltmeter-ammeter, it is important to note that the operating voltage is at the level of 12 V. The current consumption in this case is 0.5 A. The minimum resolution of the presented device is 1 mA. The shunt resistance is at 2 ohms.
The division factor of the voltmeter-ammeter is only 0.7. The maximum resolution of this model is 15 mA. The current conversion process itself takes no more than 340 ms. The permissible error of the specified device is located at a level of 0.1%. The minimum pressure the system can withstand is 12 kPa.
