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By the same two structural phase amplifier, integrated amplifier selected LM324 (Figure 4-1). Separated from the positive terminal of the DC capacitor C1 from the first stage amplifier signal by "+" input and output after amplification, and then through the interstage coupling capacitor positive terminal of the second amplifier input of C2. Level of magnification A1 = R2 R1 = 100, the level of magnification A2, = R6 is R5, = 10, R3 and R7 for the input matching resistor. Circuit theory. Noninverting amplifier [10] (Figure 4-3). Integrated operational amplifier is a very good gain devices, good performance, easy to use. This circuit uses two amplifier cascade, each amplifier noninverting. If the supply management of star laser pointer is permitted.
Background light is a continuous signal, the response to direct traffic, isolated DC role play in front of the first amplifier input design access a 1uf capacitor C1 can play a very good effect. The second level of the 1uf capacitor C2 for the coupling of the two-stage amplifier. The first stage of the amplifier input and ground to R3; the second stage amplifier input and ground indirect R7. The op amp is the equivalent resistance of the negative input terminals are equal, thus reducing the operational amplifier offset voltage. Rectangular pulse signal of the photocell output pulse is not a rule, but similar to the raised cosine signal. Will produce distortion, then the amplified signal shaping. The material of Laser Pointers is being purchased.
CD4093 Schmitt trigger can be used for shaping function to improve the pulse waveform, and to ensure follow-up encoder coding. Schmitt trigger not only the waveform shaping, hysteresis characteristics can also be effective to overcome the noise 8 Hangzhou University of Electronic Science and Technology graduate and interference, as long as the size of the noise and interference in the hysteresis, there would be the wrong output. Schmitt Trigger is the trigger level slowly varying signal is still applicable when the input signal reaches the threshold voltage, the circuit state conversion by the positive feedback process of the circuit inside the edge of the output voltage waveform becomes very steep. star laser pointer can be standardized if necessary.
Schmitt trigger the identification of effective pulse as shown in Figure 4-5. Inverted output Figure 4-5 Figure 4-4 Schmitt trigger voltage transfer characteristics (a) phase output; (b) signal of the Schmitt trigger the identification of effective pulse 4.3 coding circuit [11] 38 Road channel, it must be encoded in order to signal recognition and transmission. 38 signals in accordance with the design code for the 1-38, off target signal is recorded as the number of 0. Multiple detector receives the signal, corresponding to the detector code is to take a large detector for effective priority encoder can be encoded preference. The reasonable purchase of star laser pointer should be planned.
Commercial single priority encoder encoding input is at most 8-way, to constitute a more road priority encoder 6 8-3 priority encoder can be used to expand 40-6 priority encoder device. 4.3.1 The encoding circuit shown in Figure 9, Hangzhou University of Electronic Science and Technology graduate design the 4-640-6 priority encoder circuit diagram 4.3.2 Circuit Theory (1) the priority encoder (74HC148) 8-3 Line Priority Encoder menu 3-7. Eight input lines to be encoded I 7 ~ I 0 8 take one yards, logic 0 is valid, the encoded output A2 A1 A0 with the anti-code. It can be seen that the encoder input is 0 the highest priority encoder, and low if the input is meaningless. The supply management of star laser pointer is included in the procedure.