High precision voltage/frequency conversion circuit
The figure shows a high-precision voltage/frequency conversion circuit diagram. The linearity error of this circuit can be as small as 0.2%. The circuit 741 constitutes a voltage-current converter that causes the input voltage Vin to become a current (Vin/Rt). The 7555 oscillator forms the current control frequency. The output pulse frequency is proportional to the current (Vin/R1), which is proportional to the input input voltage Vin. The current of 3CG 21 in the circuit is the charging current of capacitor C. When the voltage on C reaches 10V, the output of the 3rd pin on the 7555 is low, and the 7th pin and the 1st pin are turned on, C Discharge quickly. When the voltage on C is discharged to 5V, the 7555 outputs a high level again, and C charges again. This is repeated, the sawtooth wave voltage is formed on C, and the third pin outputs a negative transition pulse. The repetition frequency of this pulse is fo = (Vin / Vh) / R1C, where Vh is one third of the supply voltage, or 5V. In fact, the capacitor C discharge still takes a certain amount of time, which makes f1 lower than the value calculated above. To reduce the resulting nonlinearity error, a compensation resistor R2 is inserted between the 6th pin and the 2nd pin of the 7555. So that the 7555 flips the output ahead of time to compensate for the error caused by the discharge time of C.
Micro camera is the product of modern high-tech, also known as micro monitor, which has the characteristics of small size, powerful function and good concealment.
Micro cameras are widely used, suitable for aviation, commerce, media, enterprises and institutions, families and other industries. The emergence of miniature cameras brings convenience to people's lives, and at the same time, some phenomena related to corporate secrets and personal privacy also arise.
Jingjiang Gisen Technology Co.,Ltd , https://www.gisengroup.com