coll circuit

There are generally two cases in using car camera with car display, one is the 3.5-or 4.3-inch screen, as long as it has the video signal input, the display will automatically turn on the display board camera images, the other is seven inches or more of the car displays, such displays are generally two-way video input AV1 and AV2, AV2 is usual with the camera, and AV2 have to need a dedicated power line triggered, generally the screen would have connected to switch to AV2 picture to a trigger signal to automatically switch power, just a video signal does not have to automatically switch to AV2, it must be plus a power signal. such as in the use of reversing camera, the trigger signals of AV2 display power have connected to the reversing light power after connecting video cable with display, so that reversing the screen will switch to AV2.
Off-board display is usually the case, after the reverse gear mounted camera will automatically display the picture, Another point to note is that there are some large-size display (10 inches or more of the liquid crystal display, etc.) can not the normal car camera shows the image, because the resolution of the camera will display a minimum resolution of the image does not reveal if switching to 2.4G wireless video transmission to be displayed, because the cameras image through 2.4G wireless video Mediation can be displayed.
Car camera with one car DVD navigation use: generally the case in the boot, but also have a power signal to switch to trigger the camera screen.
Car camera with a portable GPS navigation device: Generally in the boot, automatically switch to the cameras screen as long as the video signal input, no external power supply signal is triggered.

This water-level indicator uses a 7-segment display, instead of LEDs, to indicate the water level (low, half and full) in the tank. Moreover, a buzzer is used to alert you of water overflowing from the tank. The circuit shows the water level by displaying L, H and F for low, half and full, respectively. The circuit uses five sensors to sense the different water levels in the tank. Sensor A is connected to the negative terminal (GND) of the power supply. The other four sensors (B through E) are connected to the inputs of NOT gate IC 7404. When there is a high voltage at the input pin of the NOT gate, it outputs a low voltage. Similarly, for a low voltage at the input pin of the NOT gate, it outputs a high voltage.

When the tank is empty, the input pins of IC 7404 are pulled high via a 1-mega-ohm resistor. So it outputs a low voltage. As water starts filling the tank, a low voltage is available at the input pins of the gate and it outputs a high voltage. When the water in the tank rises to touch the low level, there is a low voltage at input pin 5 of gate N3 and high output at pin 6. Pin 6 of the gate is connected to pin 10 of gate N9, so pin 10 also goes high. Now as both pins 9 and 10 of gate N9 are high, its output pin 8 also goes high. As a result, positive supply is applied to DIS3 and it shows ‘L’ indicating low level of water in the tank. Similarly, when water in the tank touches the half level, pins 4 and 5 of AND gate N8 become high.

As a result, its output also goes high and DIS2 shows ‘H’ indicating half level of water in the tank. At this time, pin 9 of gate N9 also goes low via gate N4 and DIS3 stops glowing. When the water tank becomes full, the voltage at pin 1 of gate N1 and pin 3 of gate N2 goes low. Output pin 3 of gate N7 goes high and DIS1 shows ‘F’ indicating that the water tank is full. When water starts overflowing the tank, pin 13 of gate N6 goes low to make output pin 12. The buzzer sounds to indicate that water is overflowing the tank and you need to switch off the motor pump. Assemble the circuit on a general-purpose PCB and enclose in a suitable box. Use a non-corrosive material such as steel strip for the five sensors and hang them in the water tank as shown in the circuit diagram. Use regulated 5V to power the circuit.