Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Help needed

Status
Not open for further replies.

JimB

Super Moderator
Most Helpful Member
I am not sure what your problem is but lets start.

The device in the link is intended to make an electrically isolated connection between a PC serial port and some remote device which uses RS232. Also, something on the remote side must provide a 5volt supply to power the isolator.

As for using it with a USB device, the quick and simple way is to buy a USB to RS232 converter.
You could build your own USBto 232 converter but the process will be painfull and expensive.

Anything else?


JimB
 

samltd

New Member
Usb - Rs232

The problem is I want to build an USB - TTL data cable, optical isolated with the circuitry shown.
I have a schematics, I don't know if it works.

If it is as you say with USB adaptor, could I use a GSM data cable to adpt it to the optocouplers? I saw that the power in these cables is 3.3V, and I need 5V.If I can increase power to 5V, can I connect the optocoupler to the out of the GSM data cable? In my opinion, the GSM data cable creates a virtual COM port, is powered 3.3V, has the necessary drivers. The only problem are 3.3V->5V and the connection between the 2 circuitry, if is correct.

Thanks
 

Attachments

  • TEST.jpg
    TEST.jpg
    102.3 KB · Views: 172

JimB

Super Moderator
Most Helpful Member
OK lets go back to the beginning.

What are you trying to connect to?
I assume you have a PC with USB but no serial port, so you want to make a USB to RS232 (or is it TTL?) converter.
Then what are you going to connect to the converter?

JimB
 

samltd

New Member
USB connection

I am trying to connect a photo camera to PC. Camera signal is TTL. Camera connects only to serial port (DB9).
I want to use the optocouplers to isolate the connection. The point is to adapt somehow the USB to TTL, and use the optocouplers.
How else could I build an opto isolated data cable USB-TTL?
Thanks
 

Nigel Goodwin

Super Moderator
Most Helpful Member
samltd said:
I am trying to connect a photo camera to PC. Camera signal is TTL. Camera connects only to serial port (DB9).
I want to use the optocouplers to isolate the connection. The point is to adapt somehow the USB to TTL, and use the optocouplers.
How else could I build an opto isolated data cable USB-TTL?
Thanks

But WHY do you want it opto-coupled?, it makes no sense?, there's no reason to want it isolated?.

Assuming you do, for some bizzarre reason?, it's a serial camera, use the serial isolator you've already mentioned above, feed that from a USB-Serial convertor, these are freely and cheaply available.

Or, more sensibly, just feed the camera directly from the USB-Serial convertor.
 

samltd

New Member
Adapter

Initially I built this level shifter. Can't connect straight to RS232 port, since uses TTL signals.
I wanted to isolate the connection, and I found this optocoupler. Now I'd like to connect thru USB port, not serial, keeping the optocoupler.
In what I've seen I have 2 options:
First, using a FT232 to build an USB - Serial adapter.
Second, using a GSM USB Data Cable, and to connect the optocouplers to that cable. I don't know if it works, since GSM cable has 3.3V, and the optocoupler uses 5V.
What do you think? Thanks
 

Attachments

  • PC Adaptor.jpg
    PC Adaptor.jpg
    91.9 KB · Views: 153
Status
Not open for further replies.

Latest threads

EE World Online Articles

Loading
Top