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I would like to ask whether the circuit composed of 555 is astable or monostable?

I tried the configuration but it didn't work. I couldn't get 40kHz.

本帖所涉及的内容来自：超声波防盗报警探测器

lugl4313820

In fact, many cheap microcontrollers now can achieve more functions.

tagetage

The original poster should learn how to post first, at least state the main issue in the title.

For example, "Help, is the circuit composed of 555 astable or monostable?"

chunyang

555 can be built into a monostable circuit or an astable circuit (also called a self-excited multivibrator). As for the ultrasonic detection circuit cited by the original poster, it is of course an astable circuit. As for "not working", there are many possibilities, including circuit, welding, component parameter errors, etc., which need to be carefully checked.

Also note: Ultrasonic transducers require sufficient oscillation frequency accuracy. A slight deviation will greatly reduce efficiency. In this regard, if you have an oscilloscope, you can quickly determine where the problem is.

If you are making a product, it is not recommended to use the 555 solution, but DIY for learning purposes is of course fine.

maychang

[Is the circuit composed of 555 astable or monostable?]

555 can form a monostable circuit or an astable circuit, and the peripheral circuits of the two are different.

se7ens

Both single stability and no stability are OK. You can refer to the answer on the 4th floor to check whether your circuit parameters are different from the design.