Quote:
Originally Posted by TonyDuell
could you make a buffer that takes in the signals from your USB adapter and outputs solid RS232 levels?
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I have seen an ingenious circuit which used two back to back MAX232s, so the input to the circuit was RS232-level and the output from the circuit was also RS232-level, which at first sight seemed absolutely pointless.
The reason for it was that the 'RS232' output on the circuit this interface was used with was the 'right way up' for RS232 but only TTL-Level 0V-5V, which the RS232 inputs on MAX232s are tolerant of.
The input MAX232 was taking in the indifferent 'RS232' signal, passing it on inverted / at TTL level to the second MAX232 which was then re-inverting it and converting it back to full-swing RS232.
The nice thing about this dodge is that it only requires a 5V supply since the MAX232s generate their own higher voltage +/- supplies internally.