"Small improvements to the MF50 multimeter
This type of multi-purpose surface plate is relatively large, and the reading is very convenient. The accuracy of the test also meets the requirements of general use, but it does not have the battery low-voltage display function of the digital meter. In many cases, we do not know that the battery voltage is lower than the minimum voltage required by the meter. , but also use as usual to cause errors, resulting in failure to correctly judge the electrical failure, bringing a lot of trouble to maintenance. Here I introduce a method to make up for its shortcomings, which is to add a little circuit to realize the battery voltage self-check function.
First of all, we need to find a 100K five-ring metal film resistor, use a digital multimeter with a new battery, measure its accurate resistance value and record it, and then start to modify the multimeter, open the back cover of the multimeter, find Insert the two test rods into the empty position, solder one pin of the resistor to any one of the positive and negative terminals, and then find a small single-pole single-throw switch, such as the light bulb switch on the portable power supply, and string it on the resistor. , the other end of the switch, pay attention to keep it insulated from other metal parts in the meter, use a sharp blade to open a rectangular hole with the right size of the switch at a suitable place on the multimeter shell, and stick it with Black & Decker glue. The battery low voltage detection function is installed.
Next, let's improve the test lead. The test lead of this type of multimeter is very blunt and often cannot be inserted in narrow places such as phone curves. We can sharpen the test needle with a whetstone to facilitate testing. We sometimes test Some circuits need to work for a long time, but when two hands are holding the test pens at the same time, there is no way to do other things. I feel that two hands are not enough. At this time, we can prepare a few more test pens and solder them on one of the test pins. A small clip can be much more convenient, and sometimes, to test small places, we can pull out the needle and replace it with a steel needle of about 3-4CM, and the problem will be solved.
The last item is to improve the triode test jack. When testing imported triodes, it is often not easy to use, because its pin arrangement is different from that of domestic triodes, so we think of a way to change it. First, expand the test hole. , until you can insert the test lead, find a small copper plate, open three holes on it, and install three jacks, but you must install it according to the pin arrangement of the imported tube, find three test leads, you need different colors The lead of the cladding is easy to distinguish, and the corresponding position of the copper clad plate is marked, which is much more convenient in use.
We can also change the less commonly used DC 1000V gear, add a buzzer, and change it to a short-pass test gear.
The above are just some of my personal experience, just to attract more ideas, I hope there will be more good methods in the newspaper.
