Despite the fact that multimeters are always equipped with probes, in inexpensive models measuring instruments(DT 181, DT 182, DT 832, etc.) their quality leaves much to be desired. The result does not take long to arrive. It happens that not even a month passes before the owner discovers that it is impossible to take measurements with the device, because a wire has broken in one of the plugs or tips. Figure 1 demonstrates typical problem, characteristic of inexpensive Chinese products.
Figure 1. Broken wire – typical fault for Chinese productsOf course, it is not difficult to fix such a malfunction, but this will not solve the problem as a whole, and a new break will not be long in coming. This means it’s time to purchase high-quality and reliable multimeter probes, for example, Mastech products (T3033, T3009, E3029, etc.) or S-Line (ETL-5, ETL-10, ETL-11).
For the sake of fairness, it should be noted that among the products of unknown manufacturers from the Middle Kingdom, you can find quite decent analogues that will be reliable and, at the same time, in no way inferior to the original products. But to do right choice, you need to know what design features you should pay attention to. let's consider Various types test leads to determine their advantages and disadvantages. Let's start with inexpensive products.
Measuring probes, in which the wires are PVC insulated, plastic is used as the material for plugs and holders, and the tips themselves are made of steel, as a rule, the most inexpensive. They are included in the kit for budget models of multimeters, such as DT-838 or DT-830B (see Figure 3).
Figure 3. Inexpensive multimeters are equipped with appropriate probes Usually, test leads are selected different color to correctly connect the device to the circuit being measured.
The standard electrode thickness for such products is 4 mm, and the length varies depending on the model. The shape of the holders may have several variations, but this is insignificant design feature does not affect reliability.
Such products are not the best option, any careless movement may cause the tip to come off. In addition, we should not forget about the disadvantages inherent in PVC insulation, they are as follows:
It should also be noted that stylus tips with needles with a diameter of 4 mm are not suitable for all jobs. For example, to take measurements from electronic boards where SMD components are located, you will need thin probes for the tester.
The only advantage budget models- low price. Such products are fully justified when using a multimeter at a non-professional level, that is, for domestic purposes for minor repairs.
Here are some typical distinctive features, characteristic of a quality instrument:
Products from the following brands meet these requirements: Fluke, Unitrend, Mastech, etc.
Figure 4. Flucke styli complete with crocodile clips Generally good professional probes collapsible, this allows you to use special attachments for them. It makes sense to talk about them in more detail.
Many manufacturers provide connection to test leads different types attachments, which makes the probes universal and significantly expands the scope of their application (see Figure 5).
Figure 5. Test leads and attachment set Thanks to this set, you can choose long or short needles, depending on the need, change the thickness of the tip, for example, when you need to make delicate measurements, etc.
To check SMD components, it is convenient to use a special pliers attachment; testing with it is shown in Figure 6.
Figure 6. Checking the SMD resistor The alligator clip (see Figure 4) is no less useful; it can be used to connect to a device for taking measurements, while during the testing process your hands are freed, which allows you to make other measurements.
Using an attachment that has a spring-loaded hook (Figure 7), you can connect to most attachments on printed circuit boards.
Figure 7. Spring-loaded hook attachment A nozzle with a terminal adapter (Fig.) allows you to easily connect to a laboratory power supply to control voltage and current.
Figure 8. Terminal adapter Concluding the topic of professional measuring leads, you should pay attention to one significant drawback of such products - the relatively high price. For example, original Flucke probes with a set of attachments cost about $60.
It is not at all necessary to buy new test leads if the old ones cannot be repaired. Moreover, it is not difficult to make multimeter probes with your own hands. The result will be somewhat inferior to professional products, but the cost of the products will be disproportionately lower. As for quality and reliability, their level will be no worse than that of their Chinese counterparts.
First of all, you need to purchase high-quality stranded copper wire in silicone insulation. As a last resort, you can use a PVC sheath, but, as mentioned above, such probes will have a lot of disadvantages.
You can use regular fountain pens, felt-tip pens or pencils with replaceable leads as holders. Sewing needles or dart tips from the game Darts are suitable for electrodes.
Figure 9. All that remains is to glue the tip and put on the heat-shrinkable casing Second option: we use a pencil with a replaceable lead as a probe; the role of the tip will be played by a sewing needle. The manufacturing principle is almost the same, only the wire is soldered to a needle.
Related video:
Note that pen caps can be used as protective attachments for such probes.
The multimeter “suddenly” needed wires with alligator clips. I made temporary ones from what came to hand. Two years ago. The wires turned out to be a bit harsh and therefore periodically break off at the soldering points, then cursing, I solder them again and once again tell myself that I need to find wires of better quality and, in the end, make something more decent.
Soviet wires in measuring probes
And today at the market I saw used probes with suitable wires. Grandfather, over 70 years old, a radio amateur since the 50s of the last century, was selling his property. We talked (he told me how in those years, before making anything from radio components, it was necessary to first make these radio components - complete subsistence farming). I bought it solely because of the wires. “Made in the USSR” has become a serious brand in our time.
Probes and wires for multimeters
The wires were long, about twenty meters long. I decided to divide it in half. Make some with crocodiles, the second with original probes (if you can straighten their ends - they were too crooked originally). First, I straightened it on an anvil with a small hammer, after preheating the metal with a hairdryer (for better ductility). I was afraid that they would be fragile.
Measuring probes
After preliminary editing, I unsoldered the probes from the wires and continued to give them a more appropriate appearance and condition using electric sandpaper, and then with emery cloth. In the end, everything worked out. I'm thinking of using them for delicate measurements on small components.
I looked closely at the wires, because they were the ones that interested me in the first place. There were 20 copper cores under the protective sheath. Each with a diameter of 0.2 mm. I calculated the cross section: (0.2 x 0.2) x 0.785 = 0.0314 mm/kV This is the cross section of one. Accordingly, the cross-section of 20 pieces (total wire) will be 0.0314 x 20 = 0.628 mm/kV.
(for comparison: a copper wire with a diameter of 1 mm has a cross-section of 0.768 mm/sq.m.)
Homemade probes and wires
It turned out to make these two pairs of measuring wires. With crocodile clips and probes.
Checking wire resistance
Since the accuracy of measurements is affected by the resistance of the wires, I could not resist making comparative measurements (although for my amateur radio practice this is not at all significant). The wire with the probe included with the multimeter is 0.5 Ohm.
Wire with probe from production times Soviet Union- 0.4 Ohm. For the sake of objectivity, I note that it is 20 cm shorter.
Chinese and homemade probes for the tester
The photo clearly shows the difference between what was and what has become. It took an hour to do everything about everything. The opportunity for this was made possible by the exceptionally successful acquisition of profile wires. But now, having looked under the sheath, we have a real idea of what kind of wire we need to look for for the manufacture of measuring wires (multi-core, with a diameter of one core of 0.2 - 0.3 mm and with a total cross-section of all cores of 1 mm, while the wire sheath should be quite thick and at the same time elastic). Author - Babay iz Barnaula.
Hi all!
Now on sale various testers, but in most cases the probes for them are of low quality.
There was a case where in the cold the wires of the probes broke like matches. So I decided to make the missing probes myself.
Trying on a dart tip. It needs to fit the size of the pen tip. If it doesn't fit, you'll have to cut off the thread on the handle. If this does not help, then you will have to find other pens.
Take the tip of the dart and heat it gas burner. After sufficient heating, take a piece of solder dipped in soldering acid, and throw it inside. We lower the wire there and wait for the solder to cool.
We assemble the dipstick. It is better to glue the tip.
Second set. Probes with needles for puncturing insulation. We take pencils with replaceable leads and take them apart.
We take needles and try them on instead of leads.
Solder the wires to the needles.
Insert the needle and wire into the pencil from behind. It may not work the first time; you need to hit the center of the pencil collet. The needles must be glued into the collet, otherwise they will go inward when pressed.
In general, everything is ready, all that remains is to solder the plugs to the wires and cover the probes with colored heat shrink. Be careful with the hairdryer! The plastic of office supplies may become deformed.
Pen caps came in handy too.
Addition. While disassembling the computer power supply, I discovered a connector whose terminals fit very well on all probes, including Chinese and Soviet ones.
Therefore, I decided to also make crocodile attachments. We remove the terminals; they are held in the block by latches. Press the latch with an awl and remove the terminal. We cut off the shank at the terminal and bend the latch inward.
We take the alligator clip, insert the terminal, and solder it.
The crocodile is ready.
Thanks to all. In conclusion, I will say that I bought wires with frost-resistant insulation with a cross section of 0.75 mm?.
Measurements with a multimeter are made using probes. Not all multimeter probes included in the kits have good quality, so it would be preferable to make them yourself. It doesn’t take much time, but then it makes it possible not to be distracted by replacing them. It is also possible to equip the probes with crocodile clips, which will free your hands while taking measurements. Sometimes it is useful to have both measuring collapsible thin probes and a model with alligator clips; each of them will be indispensable in certain situations.
Alligator probes are very convenient to use if you need to fix a conductor for accurate measurements with a multimeter. To carry out the work you will need the following tools and components:
Wires use stranded copper because copper has good conductivity and flexibility. Silicone shells are soft, flexible, and will not break or crack over time. You can find an option specifically designed for black and red multimeters.
To make homemade probes, you need to connect the wires with plugs and clamps. If you know how to solder and have everyone necessary tools the procedure will take no more than half an hour.
It is advisable to select the same color for the plug, wire and clamp, so that one probe is, for example, completely red, and the second completely black. In this case, the multimeter will be convenient to use and it will be easy to observe polarity when taking measurements.
First, you need to insert the wires into “bananas”, through which they will be connected to the multimeter. The connection with the plug is not particularly difficult.
A bolt is unscrewed from the banana, after which a wire can be inserted inside, the end of which has been stripped in advance. Then you need to tighten the bolt, thereby securely fixing the wire inside. The same operation is performed with the other wire. At this point, the “bananas” can be considered connected.
On at this stage strip and tin the free ends of the wires that will go to the alligator clips. Next, take a crocodile clip for a wire that matches the color. The insulation is removed from it and the bolt is unscrewed.
Clamping the wire with bolts is not the most reliable solution for multimeter probes. It will be better to solder it in this place, having first made a small soldering pad out of tin. The second “crocodile” also joins.
Now you can start soldering the crocodile. To do this, a wire is inserted inside, bringing the tinned end to the prepared area.
The wire must first be covered with crocodile insulation so that it can then be pulled over the connection.
Solder is taken and the wire is soldered to the crocodile. The soldering must be strong so that the wire does not fly off at the slightest tension. When the wire is soldered, you need to clamp it with the lower edges of the crocodile body; this can be done using pliers.
After this, strong clamps are formed, which will guarantee long-term serviceability. homemade probe. Next, the insulation is put on the crocodile. This is necessary for its reliable and safe operation, as well as for its aesthetic appearance.
You can also make thin probes for a multimeter. The cheapest and easiest option is to make them from the body of handles. Everything here is very similar, only instead of clamps you will need the following parts:
As a tip, either buy special thin probes for a dt multimeter, or use thin sewing or medical needles. It is better to use special probe needles, purchasing them on the radio market or in an online store.
Everything else you need is the same as in the previous version of making probes for a multimeter. The plugs are connected in the same way as described above, and securing the tips of future probes has several features.
To begin with, one hole is made in the top caps of the pens. This is necessary for the wire to go inside. It is desirable that their diameter matches the diameter of the wire. Next, the lower part of the handle is disassembled and a needle is inserted into it.
The needle must be soldered to the wire, which is previously inserted into the cap. The solder should not be made too thick, but it must be soldered securely. The soldering process was also discussed above.
When everything is ready, silicone is poured into the lower part of the handle and until it hardens, the needle sticks out according to the level. She should not be disturbed for several hours.
You can do it this way. First, stick the needles out 4-5 cm, then put on the cap. Thus, the tips for the probes will independently take the desired position. When the silicone has hardened, the structure is strong and comfortable.
To check the device for functionality, you need to measure the resistance of the probes. To do this, you need to connect the multimeter to the network and set the switch to measure resistance.
If the multimeter does not have automatic range adjustment, you need to switch to measuring the lowest limit.
Insert the leads of the probes into the sockets of the device, and then connect the probes to each other. The resistance figure should be 0, or as close to zero as possible. If the multimeter is automatic, then a couple of seconds after the circuit is closed, the device itself will set to 0.
If you know the sequence of the process, then all the work will not be difficult. You need to have minimal soldering skills, and then everything will be done quickly, and the device will last for many years.
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