[SOLVED] How do get 5V square waveform from 24V square waveform?

[manikandan123]

hi,
I want to get 5V square waveform from the 24V square waveform for my one of the application.please provide some details.

 

[kak111]

What is the frequency and needed load current for 5V square

 

[manikandan123]

What is the frequency and needed load current for 5V square

my application is zero cross detection. I used Capacitive transformer-less power supply. first i got 24V and then i take 5V from 24V. so the output OF RC is 24V square wave. I want to get 5V square waveform from that 24V square waveform to give the signal to MICROCONTROLLER. give some suggestion.

 

[kak111]

So frequency is 50Hz, and cause you use transformerless supply, best way to protect MCU is to use optoisolator.
Connect led side via resistor to 24V square and take 5V square out via optotransistor / resistor connected to 5V MCU supply.

 

[biff44]

how about a series resistor and a 4.7v zener diode

 

[alexan_e]

I think it would be best to use the optocoupler to isolate the mcu and the rest of the surrounding circuit from the mains unless the mcu is already powered by this transformless power supply.

Alex

 

[manikandan123]

I think it would be best to use the optocoupler to isolate the mcu and the rest of the surrounding circuit from the mains unless the mcu is already powered by this transformless power supply.

Alex

The MCU is already powered by this transformerless supply.

---------- Post added at 11:29 ---------- Previous post was at 11:19 ----------

@kak111 The MCU is already powered by this transformerless power supply. what i think is, may i use voltage divider in that place. suppose i will used 5:1 voltage divider,the result may get around 5.2V. Is This voltage divider cause any problem. After the RC I will take two resistor with the range of 5:1 in series and second resistor is connected to Ground. so i will take output between these two resistor.may be it will 5V square wave.Am i right

---------- Post added at 11:35 ---------- Previous post was at 11:29 ----------

how about a series resistor and a 4.7v zener diode

@biff44. after the 24V zener I connected capacitor (for noise reduction) and then normal diode with 1.5K series resistance and then connected parallel 5.1 V zener and also capacitor. so i got 5V at output side.

 

[kak111]

after the 24V zener I connected capacitor (for noise reduction) and then normal diode with 1.5K series resistance and then connected parallel 5.1 V zener and also capacitor. so i got 5V at output side.

This is OK.

 

[manikandan123]

This is OK.

@ kak111. ok.That is used for power supply. in final we get 5VDC .I got square wave at the point of next node of RC combination.I checked with CRO.the result is 26 square wave at 10ms period.I used voltage divider in this case to convert 24V to 5V. Finally i got 5V squarewave. thanks for your all reply.