Isolate 2 inputs with optocoupler

Thread Starter

brodonh2

Joined Jan 22, 2023
9
Hi All,
I want to isolate the 18vdc from the 15vdc inputs.
Circuit is for driving a pulse motor with sicfets and have the ability to adjust the pulse width on the fly with pot.
It works but there is interference between the 2 inputs.
Wise direction would be greatly appreciated.
Thanks,
Donald
 

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BobTPH

Joined Jun 5, 2013
9,301
Analog or digital signals?

Are all the grounds of the signal senders and receivers connected together?

We are going to need much more information about what is creating the signals and how they are used.
 

sghioto

Joined Dec 31, 2017
5,431
From the pcb layout it appears one would cut the common negative connection on the 15 and 18 volt supplies.
Then use an opto on the output of the 555 circuit for isolation.
1714434326582.png
 
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Thread Starter

brodonh2

Joined Jan 22, 2023
9
Hi sghioto,
Yes, I received a similar suggestion form another EE friend.
Before building a new sche, I decided to join the positives along with the grounds and input 16V for both the 555 and the fet driver. The sic fets that I'm driving can go with 15v-0v for switching and the 555 can handle 16v. This approach solved the problem and it is working as desired. It is interesting to note (for me) that the 555timer gives super clean pulses for the driver.
Better than what I was seeing without the 555.
Thank you all for being here.
brodonh2
 
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