Actually, certain to having car drives for the person of experience, usually the speedometer of the car and effective rate are worth same existence deviation. GB regulation, speed of speed watch directive is not gotten under actual speed, and demonstrative speed and actual speed must achieve such requirement: 0 ≤ indicate speed - actual speed ≤ (actual speed / 10) + 4. That is to say, if demonstrative speed is 40km/h when, actual speed should be to be between 32.7-40km/h; If demonstrative speed is 60km/h when, actual speed should be to be between 52-60km/h.
Have behind general appearance adjustable resistor screw, pass it to be able to do a simple fine tuning. You are for instance actual full fast 30, rise frame, pull highest, the rate that tone resistor shows liquid crystal screen is moved to 3334, after that reload good trial run. You can discover, liquid crystal watch becomes accurate, every 50 lis do not differ with actual kilometer 5 kilometers.
Some need open appearance, there is the crossed knob of an orange inside, be sure to keep in mind fine tuning. Some may be a certain fixed great resistance inside, can search at that time adjustable potentiometer will change it, move next adjustable potentiometer.
There was a mobile phone now very convenient, install a GPS to measure speed APP, OK and actual contrast. Nevertheless GPS measures fast response a bit slow, the instant is measured commonly quickly is not very accurate.
