Rendering demonstration of two-way water level sound and light alarm_Basic hardware circuit diagram explanation

Circuit diagram:

Circuit function introduction:

The water level alarm in this example can sound an alarm when the water level is too high or too low. At the same time, it also adds an indicator light display. According to the indicator lights of different colors, it can also be judged whether the water level is too low or too high.

In this example, the upper limit water level is point C, the lower limit water level is point B, and the normal water level is between BC.

Circuit diagram analysis:

The entire circuit can be divided into the following parts:

One is the upper limit water level alarm switch circuit composed of transistor Q1, probe C, and light-emitting diode D3;

The second is a lower limit water level alarm switch circuit composed of transistors Q2, Q4 and light-emitting diode D4;

The third is a complementary multivibrator audio oscillator circuit composed of transistors Q3 and Q5.

The entire circuit working process is as follows:

When the water level is between BC and has not reached point C, it is the normal water level:

1. After the circuit is powered on, the transistor Q1 is in the cut-off state, and the light-emitting diode D3 is in the extinguished state and does not display.

2. At this time, the base of transistor Q2 can obtain the base current through the water path between probe AB to turn Q2 on. After Q2 is turned on, the emitter junction voltage of transistor Q4 is exactly the collector-emitter voltage of Q2, that is, the tube voltage drop of transistor Q2. Since there is a large resistor of 470K connected to the emitter of Q2, the voltage drop of the tube of Q2 will be very small, close to 0V, so the transistor Q4 is cut off.

3. After the transistor Q4 is cut off, the light-emitting diode D4 is extinguished and does not display; at the same time, the complementary audio oscillator has no alarm signal input and will not oscillate, so the speaker will not sound.

When the water level exceeds point C:

Transistor Q1 obtains the base current through the water path between the probe AC ​​to turn Q1 on, and the light-emitting diode D3 is lit through the current limiting resistor R1. At the same time, part of the current output by the emitter passes through diode D1 to resistor R4, causing the left end of resistor R5 to be at high level. Transistor Q3 obtains base bias current, the complementary self-excited multivibrator audio oscillator starts to oscillate, and the speaker emits an alarm sound.

When the water level is lower than point B:

The transistor Q2 is turned off, and the base of the transistor Q4 is at a low level, causing the transistor Q4 to be turned on, and the light-emitting diode D4 is lit through the current limiting resistor R3. At the same time, part of the current output by the Q4 emitter passes through the diode D2 to the resistor R4, causing the left end of the resistor R5 to be at a high level. The transistor Q3 obtains a base bias current, the complementary self-excited multivibrator audio oscillator starts to oscillate, and the speaker emits an alarm sound.

Diodes D1 and D2 function as an OR gate, that is, whether it is an upper limit alarm or a lower limit alarm, as long as there is an alarm signal, the oscillator will start.

-The Electronic Components Purchasing Network (www, oneyac, com) is a local component catalog distributor. It adopts the "small batch, spot, sample" sales model and is committed to meeting customers' procurement needs for multiple models, high quality, and fast delivery. Self-built and efficient intelligent warehousing, with over 50,000 self-operated inventories, provides one-stop genuine spot procurement, personalized solutions, option substitution and other diversified services. (This article is compiled from the Internet for the purpose of disseminating useful information and knowledge. If there is any infringement, please contact the administrator to delete it)

Circuit diagram:

Circuit diagram functions:

By changing the charging and discharging resistance of the capacitor and changing the pulse width of the pulse train, the average DC voltage of the small DC motor is indirectly changed, thereby changing the speed.

Circuit diagram explanation:

In the circuit, resistors R1, C2, and inverter U1A form a simple multivibrator. However, due to the existence of two diodes D1 and D3, the unidirectional conductivity of the diodes is used to make the charging loop and discharge loop of capacitor C2 pass through Different resistance values, so that by adjusting R1, the duty cycle of the square wave output by U1A can be changed.

The output of U1A is reversely output through the NOT gate U1B, making the adjustment of R1 proportional to the output.

The high level output by U1B turns Q1 on and the DC motor works. Therefore, by adjusting R1 to make the average conduction time of Q1 longer, the average DC voltage flowing through the DC motor will be greater and the speed will be faster; conversely, the speed will be slower.

Notice:

This example uses CD40106, which is a 6-NOT gate integrated chip, so there are 4 more NOT gates that are not used, so you can choose them yourself!

-The Electronic Components Purchasing Network (www, oneyac, com) is a local component catalog distributor. It adopts the "small batch, spot, sample" sales model and is committed to meeting customers' procurement needs for multiple models, high quality, and fast delivery. Self-built and efficient intelligent warehousing, with over 50,000 self-operated inventories, provides one-stop genuine spot procurement, personalized solutions, option substitution and other diversified services. (This article is compiled from the Internet for the purpose of disseminating useful information and knowledge. If there is any infringement, please contact the administrator to delete it)