The DT-830B multimeter is a Chinese-made device that many use. Those who constantly deal with electronics can not do without such a technique. This article talks about what a DT-830B multimeter is. An instruction with a detailed description of the device allows even beginners to use it.
Many models are produced, differing in quality, accuracy and functionality.
The device is intended for the following basic measurements:
- electric current values;
- voltage between 2 points in an electric circuit;
- resistance.
In addition, the DT-830B multimeter and other related models can perform many additional operations:
- ring the circuit at a resistance below 50 Ohms with an audible alarm;
- test the semiconductor diode for integrity and determine its forward voltage;
- check semiconductor transistor;
- measure electric capacitance and inductance;
- measure the temperature with a thermocouple;
- determine the frequency of the harmonic signal.
How is the multimeter arranged?
- The dial shows the measured values in the form of numbers on a plastic or glass display.
- The switch provides a change in the functions of the device, as well as switching ranges. In the idle state, it is set to the off position.
- Sockets (sockets) in the case for installation of probes. The main thing, with the inscription COM and negative polarity, has a general purpose. A probe with a black wire is inserted into it. The next one, marked VΩmA, has a positive polarity with a red probe.
- Test flexible wires of red and black color with pincers.
- Panel for transistor control.
Multimeter DT-830B: manual with a detailed description of measurement modes
Not everyone understands how to measure the necessary parameters with the device. When a DT-830B multimeter is used, the instruction manual must be followed exactly. Otherwise, the device may burn out.
1. Resistance measurement
The function is necessary when you need to conduct wiring in the apartment or find a break in the home network. Not everyone knows how to use a multimeter in this case, but you just need to set the switch in the resistance measurement sector to the appropriate measurement range. The device has an audible alarm that the circuit is closed. If there is no signal, this means that somewhere there is a gap or a value of the circuit resistance above 50 Ohms.
The range of minimum resistances (up to 200 Ohms) is called a short circuit. If you connect the red and black probes together, the device should show a value close to zero.
The Chinese-made DT-830B multimeter has the following features when measuring electrical resistance:
- High error of indications.
- When measuring small resistances, the value obtained at the contact of the probes should be subtracted from the readings. To do this, they are previously closed. On the remaining ranges of the sector, the error decreases.
2. How to measure DC voltage
The device switches to the DCV sector, divided into 5 ranges. The switch is set to a deliberately larger range of values. When measuring voltage powered by a 3 V or 12 V battery, you can set the sector to "20". It should not be set to a large value, since the error of the readings will increase, and with a smaller device, it may burn out. With coarse measurements, if accuracy of only 1 V is needed, the multimeter can be immediately set to the “500” position. Similarly, they do when the measured voltage is unknown in magnitude. Then you can gradually switch the range to smaller values. The “HV” warning, which lights up in the upper left corner, signals the highest measurement level. High voltage values require caution in working with the device, although as a voltmeter from the DT-830B multimeter, it is more reliable than an ammeter or ohmmeter.
Observance of polarity of probes for the digital device is optional. If it does not match, this will not affect the value of the readings, and the “-" sign lights up on the left of the screen.
3. How to measure AC voltage
Installation in the ACV sector is the same as in DCV. High voltage of 220-380 V can lead to failure of the device if it is connected incorrectly.
4. Measurement of direct current
Low currents for electronic circuits are measured in the DCA sector. In these switch positions, voltage measurement is not permissible. In this case, a short circuit will occur.
To measure current up to 10 A, the third socket is used, into which the red probe should be rearranged. Readings can be taken in just a few seconds. Typically, an ammeter measures the current of electrical appliances. In this case, use the device carefully and when the measurements are really necessary.
5. Monitoring the health of diodes
In the opposite direction on the diode, the device should show infinity (unit to the left). In the forward direction, the voltage across the junction is 400-700 mV.
In this sector, you can also check the health of the transistor. If you imagine it as two counterclockwise diodes, you must check each transition for a breakdown. To do this, it turns out where the base is located. For the pnp type, it is necessary to find a pin (base) with a positive probe so that the negative probe shows infinity on the other two (emitter and collector). If the transistor is of type npn, the base is a minus probe. To find the emitter, it is necessary to measure the resistance of its transition, which is always greater than the collector. For a working element, it should be in the range of 500-1200 Ohms.
By calling the transitions with a multimeter in the forward and reverse directions, you can determine whether the transistor is working or not.
6. Sector hFE
The device can determine the current gain of the h21 transistor. To do this, just insert its 3 pins into the corresponding socket sockets. The display immediately shows the value "h21". To get the correct results, it is necessary to distinguish between the types pnp (right side of the panel) and npn (left side).
7. Opportunities for improving the device
The instruction on a multimeter DT-830B provides a certain number of functions. The models differ slightly from each other, and if desired, you can improve any, for example, add a measurement of the capacitor capacitance, temperature and all other additional functions listed above.
The description of the DT-830B multimeter in advertisements and reviews is quite true.
The basis of the multimeter is an analog-to-digital converter (ADC).
Multimeter DT-830B: scheme and repair
For an inexpensive small-sized device, the ICL7106 chip is most often used.
When measuring voltage, the signal enters from the switch through a resistor R17 to the input 31 of the chip. When the AC voltage is measured, it is rectified through the diode D1, after which the signal also passes through the chain to the output of the 32 microcircuit.
The measured direct current creates a voltage drop across the resistors, after which the signal is also fed to input 32. The microcircuit is protected by a 0.2 A fuse installed at the input.
The device often fails when contacts are lost and when turned on incorrectly. First of all, the fuse is checked and changed.
The device reliably works when measuring voltage, since it is well protected at the input from overloads. Failures can occur when measuring resistance or current.
Burnt resistors can be determined visually, and diodes and transistors can be checked using the methods described earlier. Checks for breaks and the reliability of contacts.
When repairing the instrument, the power supply is first checked. Then, the health of the chip is checked. It should be workable if the voltage at terminal 30 is 3 V, and there is no breakdown between the power and the general output of the microcircuit.
When disassembling, do not lose the switch balls, without which there will be no reliable fixation of it.
When to change the battery?
The power supply of the device changes in the event of disappearance of numbers on the display and deviation of the measurement results from approximate known values. A battery image appears on the screen. To replace it, you need to remove the back cover, remove the old one and install a new element.
Using the DT-830B multimeter is very convenient: the battery changes easily and very rarely. Only you need to work with him very carefully. The device can be easily burned if used improperly.
Product reviews
About such a device as a digital multimeter DT-830B, reviews are mostly positive. It is unpretentious, multi-functional, and the battery lasts for years. Everyone is satisfied with the low price of the device. Comments appear only on trifles.
The probes should be replaced, as they fail quite quickly. Their resistance is close to the standard and is 0.5 ohms.
Conclusion
The DT-830B multimeter is a universal device necessary for the home master and for the professional. It has many important features and is inexpensive. For successful use, it is necessary to study in detail what a multimeter DT-830B is. The operating instructions must be strictly observed so that there are no errors leading to the failure of the device.