Who hasn't already done it, some mistake, gauge pulled and then this: The values can't be right. Yes then you have measured crap again. But often you quickly find your mistake.
Therefore, it never hurts to have a second measuring device for inspection. And wouldn't it still be cool to build it yourself? Well, developing a measuring instrument yourself is a bit more difficult, but we have a kit in the shop for it.
So you can use it to assemble your own measuring instrument.
Here in the blog we explain the individual steps.
Before we start with the kit, we check if everything is included:
It is very helpful to sort the resistors beforehand:
This resistance level table helps you to do this:
|Ring color||1st Ring||2nd Ring||3Ring (multiplier)||4. Ring (tolerance)|
|Bro||Brown||1||1||× 10||1 %|
|Rt||Red||2||2||× 100||2 %|
|Gn||Green||5||5||× 100000||0,5 %|
|Bl||Blue||6||6||× 1000000||0,25 %|
|Vi||Purple||7||7||× 10000000||0,1 %|
|Dg||Gold||-||-||× 0,1||5 %|
|Sr||Silver||-||-||× 0,01||10 %|
Special attention must be paid to the tolerance rings!
|1||0.99 x 0.5%||R10||Sw||Ws||Ws||Sr||Gn|
|2||900" -0.5%||R17, R20||Ws||Sw||Sw||Sw||Gn|
|1||9k x 0.5%||R21||Ws||Sw||Sw||Bro||Gn|
|1||90k x 0.5%||R22||Ws||Sw||Sw||Rt||Gn|
|1||352k x 0.5%||R23||or||Gn||Rt||or||Gn|
|1||548k x 0.5%||R27||Gn||Ge||Gr||or||Gn|
|1||1k x 1%||R5||Bro||Sw||Sw||Bro||Bro|
|3||10k x 1%||R6, R16, R30||Bro||Sw||Sw||Rt||Bro|
|1||33k x 1%||R7||or||or||Sw||Rt||Bro|
|2||47k x 5%||R25, R36||Ge||Vi||Sw||Rt||Dg|
|1||120k x 5%||R1||Bro||Rt||Sw||or||Dg|
|9||220k.5%||R4, R12, R13, R14, R19, R18, R24, R33, R35||Rt||Rt||Sw||or||Dg|
|1||1M. . . . . . . . . . .||R3||Bro||Sw||Sw||Ge||Dg|
|2||2M. . . . . . . . . . .||R15, R26||Rt||Sw||Sw||Ge||Dg|
After we have sorted our resistances, we start soldering.
We start with the resistors R1, R36, R35, R33 on the top right and with R14, R13, R12, R24 on the top left, because they are soldered lying down.
All remaining resistors are soldered to the correct positions according to the table above, but not lying, but standing. As can be seen in the picture R3.
This is done with all the other resistances. Until in the end all resistances were soldered.
After the resistors, we sort the remaining components:
Let's start with the capacitors:
|C2, C4, C5, C6||100pF||104J|
After the capacitors we mount the transistors (Q1 = 9013, Q2 = 9015), the diode (1N4007), the thermistor (R32 = 4B DMZ) and the potentiometer (VR1 = 200)
In the next step, we solder the fuse holder, the 9V battery clip (without the connected battery) and the Piezzo speaker (BZ).
It is recommended to attach the Piezzo speaker with double-sided tape (or similar) to the board.
Now the 3 measuring contacts can also be soldered, these can be easily positioned when soldering directly in the housing. BUT ATTENTION: The metal drains the heat very well, do not solder for too long, otherwise the plastic housing will melt !!!
Last but not least, we solder the 2 switches and the socket strip on the back.
Now we have finished the soldering work and it can go to the assembly.
First we take the front of the case and place the display in the window and on top of it on the underside, we place the conductive rubber strip.
To the right and left next to the round selector switch are 2 holes, in these come the 2 springs, on which the 2 balls are placed.
We then carefully place the selector switch on the 2 balls in the designated cut-out and also place the 2 small yellow buttons in the recesses under the display.
Carefully we now place the board on the housing and try not to move the selector switch and hit all the holes in the middle. If everything is positioned correctly, we screw the board into the housing with 6 screws.
We pressed the rubber onto the display and pressed the selector switch onto the balls.
Now we set the meter to 20V for example, in order to be able to perform a calibration. We connect a battery to the open meter. Now we measure the voltage of another battery (for example 9V) with another meter. We remember this voltage and measure it with our new measuring instrument. If the voltage now differs, we can set it with the potentiometer on the back until the voltage is displayed identically to the other meter.
If we have calibrated the meter, we can remove the battery and assemble the housing ready. To do this, thread the battery clip through the hole in the battery compartment and screw the housing together.
You have now assembled your own meter. We wish you a lot of fun and success in your projects and the meter will surely be your good companion.