Bought a lazy multimeter

dcexpert

Bought a lazy multimeter [Copy link]

 

 
I bought a new multimeter last week. Actually, there is no shortage of multimeters now, but the Fluke multimeter I have been using is good in every way, except that every time it automatically shuts down, I need to turn the knob to OFF again before I can turn it on, and some functions need to be switched to the second or even third function. In fact, we don’t use many functions frequently, and the most commonly used ones are 2-3 functions. It feels a bit troublesome to turn it on every time. I happened to see a small and cheap multimeter that claims to have full automatic functions, which means it can automatically identify common functions such as voltage, resistance, on-off, and automatically switch ranges without shifting or switching. In addition, it uses ordinary AAA batteries, which is more in line with my ideas, so I bought one. Comparing Fluke 107 and ZTS1, Fluke’s workmanship is better in comparison The whole multimeter has only 3 buttons. The red button in the middle is the power button, or it can automatically shut down after waiting for 15 minutes. The NCV on the left is used to test the AC induction signal, which is used to test the live wire; the button on the right is the backlight switch. When there is no test signal, the Auto symbol will be displayed. Below are the holes for the three test leads. The two on the right are used for regular measurements, and the left one is for testing current. They are taped by default to prevent incorrect connections. This multimeter looks very simple. I wanted to see the internal structure, so I took it apart. Remove the rubber cover around the multimeter, and you can see two screws. There is another screw located in the battery box under the bracket. Remove the screws and you can see the circuit board. The entire circuit board is very simple, with only the main chip, buzzer, voltage divider resistor, light-emitting diode, fuse, etc. The battery is not connected using a plug or wire welding, but through contacts. Battery box and back cover Main chip and buzzer Below is a row of high-power precision resistors. However, we did not do a precision comparison test, so it should not be too good, nor too bad. What is strange is that the current test part is welded with a pin header (in the upper right corner), which does not look very good. After removing the three screws on the main board, you can also remove the main board. There is almost nothing on the front of the main board except the button contacts and LCD contacts. The white object connected to the main board is not the LCD, but the backlight of the LCD. Finally, take a look at the top cover of the multimeter, which has three silicone buttons and LCD. Overall, it is a very simple pocket multimeter.

sxccxz

Is your Fluke too low-end? The one I use can shut down automatically

dcexpert

sxccxz posted on 2018-10-29 10:23 Is your Fluke too low-end? The one I use can shut down automatically

It can shut down automatically, but it is more troublesome to turn it on after shutting down. It must be turned to OFF before it can be turned on

star_66666

He loves to disassemble machines.

曹伟1993

If you don't buy it for the purpose of taking it apart for fun, it will become meaningless, hahahahahahahahahahaha

dcexpert

Cao Wei 1993 posted on 2018-10-29 12:36 If you buy it not for the purpose of disassembling it for fun, it will become meaningless, hahahahahahahahahahahahahahahahahaha

Indeed

dcexpert

star_66666 posted on 2018-10-29 12:28 This guy really loves to disassemble machines

Disassembling machines makes people progress

PowerAnts

I'm so lazy.

xujian2000

Interesting, dismantling other people's equipment can be used for reference, and you can also see other people's processing methods, good!

曹伟1993

dcexpert posted on 2018-10-29 12:47 Indeed

If you are well, it will be a sunny day. If you are not well, then see you in the trash can~~~~~hahaha

star_66666

dcexpert posted on 2018-10-29 12:48 Disassembling a computer makes people progress

What Lao Yang said makes sense, I will follow your example

joywyc

Since it has been disassembled, it is not a bad idea to study it. The main questions are: (1) How to realize automatic identification, voltage or resistance, especially identification of millivolt AC voltage or high resistance? (2) How to switch between high and low voltage? The board should use analog switches, but it seems that the withstand voltage is not enough when measuring high voltage. How to solve this problem? In addition, considering that the current range is tested separately from the voltage and resistance range, automatic switching measurement should not be a problem.

sf116

Judging from the workmanship, it should be produced in a small workshop

micon

How is the accuracy?

dcexpert

micon posted on 2018-11-16 11:37 How is the accuracy

It's OK. The maximum reading is 3999

cyh924417122

dcexpert posted on 2018-10-29 10:27 It can be turned off automatically, but it is more troublesome to turn it on after turning it off. It must be turned to OFF before it can be turned on

I also think that the previous 17B can be awakened by pressing the function switch key

btty038

It's really simple

zhuyebb

Good post, thumbs up! Thanks to the host

liushiming82

The author of the post, you should explain to everyone the testing principle of each gear, because many people like me don’t know the testing principle of the multimeter, how to repair it if there is a problem with any part, etc.

dcexpert

liushiming82 posted on 2018-12-20 09:20 OP, you should explain the testing principle of each gear to everyone, because many people like me don’t know the testing principle of the multimeter. If there is any problem...

Although the principle of the multimeter is not complicated, it is not something that can be explained clearly in one post. There are books on the principle of multimeter in bookstores, you can buy one for reference.