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Scaling down a 12V sqaure pluse to 5V square pulse

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adigwe

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Hello,

Could any one let me know how to convert a 12V pluse from a 555 timer to a 5V pulse.

Thanks
 

One of options is to use 1kΩ resistor and 5.1V zener diode .. see attached picture ..

Regards,
IanP
 

hi

Mininum operating voltage of 555 IC are 4.5V. u can use a 5V or 5.5V supply to get a 5V pulse
 

In addition to IanP's suggestion, there are many other techniques. Here are just a few

1. resistor divider (high output impedance)

2. comparator

3. optical isolator

4. CMOS IC CD4050 or CD4049 with 5V supply (these do not have internal diodes on the inputs) and will withstand up to 18V input

5. Any 5V logic gate with a current limiting resistor in series, possibly with a clamping diode (Schottky is preferable) to 5V supply.

-Aubrey
 

optical isolator is a circuit which uses couples a particular input on one part of the circuit to another part of the circuit without any physical connectivity.... it uses a LED in the input side and the device used on the other side varies one of its parameter in accordance with the LED emission and this is how the coupling takes place....
 

Practically, you can use one of the 2 solutions suggested by IanP and antedeluvian: Both of circuits of resistor with zener diode and resistor divider are simple and reliable.

nguyennam
 

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