How to make digital display scales?

The electronic scale is a kind of precision electronic instrument, which is easy to operate, high precision and practical, but it is slightly more expensive than the traditional mechanical scale. Today we will teach you a way to make digital display electronic scales. You can try DIY children's shoes that are easy to use. The most important thing is to do it yourself. Of course, you still need to know some knowledge about the structure and working principle of the electronic scale before you do it. Let's take a look at the specific method.

First, the component selection

1. IC1 selects ICL7126 integrated block; IC2, IC3 selects high precision low temperature standard precision op amp OP-07; IC4 selects LM385-1.2V integrated block.

2. The sensor RI uses E350-ZAA foil type resistance strain gauge, and its normal resistance is 350O.

3. Precision metal film resistors should be used for each resistor element.

4. RPI uses precision multi-turn potentiometers. RP2 and RP3 can be replaced by precision metal film resistors after debugging.

5. In the capacitor, C1 uses a mica capacitor or a ceramic capacitor.

Second, the production and commissioning of electronic scales

It is known that the deformed steel piece can be made of ordinary steel saw blade by first smoothing the saw tooth, heating the saw blade to reddish, heat-processing into a "U" shape, and drilling at the corresponding position for later installation. Then it is heated to orange-red (to get seven or eight hundred degrees Celsius), quickly released into cold water quenching to improve hardness and strength, and finally surface treatment process. The scale hook can be glued to the bottom of the steel with super glue. The strain gauges are bonded to the most deformed part of the steel (medial center) with a special strain adhesive. At this time, the change in force is just the opposite of the change in resistance. The æ‹Ž ring application activity chain is connected to the scale body so that the scale body can hang freely when in use, and the æ‹Ž ring should also be hooked on the same vertical line as the scale.

During the commissioning process, 1 kg and 2 kg standard weights should be prepared. The process is as follows:

1. First, adjust the RP1 when the scale body naturally hangs without load, so that the display accurately displays zero.

2. Then adjust RP2 to make the scale body bear the full scale weight (this circuit selects the full range of 2 kg) to display the full scale value.

3. Then hang the 1kg standard weight under the scale hook to see if the display shows 1.000. If there is any deviation, adjust the RP3 value to make it accurately display 1.000.

4. Repeat steps 2 and 3 to make them meet the requirements.

5. Finally, the resistance values â€‹â€‹of RP2 and RP3 are accurately measured and replaced with fixed precision resistors.

6, RP1 can lead to off-balance sheet adjustment. Adjust RP1 before measuring to return the display to zero.