Hi all,
My application is based on to sink voltage from RS232 (DB9 connector) port to operate my device.
As we all know RS232 generate around +-15V as per the data bits on TX pin. -15V for logic 1 and +15V for logic 0. I need to operate my device by getting this voltage as a supply.
I test my device by sending the consecutive 0s to TX pin from my microcontroller and I get +9V through TXout pin of my MAX232. It had enough current to operate my device as MAX can able to supply 8 to 10 mA current. The device works fine same as by supplying separate VCC.
The problem is with the -9V from the same TX pin when I raise my data to 1 instead of 0. As I connect my device to TX pin, so there is no way that I can control the data bits from the host device. So the only thing I have to do is to convert the negative voltage to positive. If somehow I can able to convert that - 9V to positive +9V it will provide the continuous supply to my device.
I tried few voltage inverters, boost ICs, DC to DC voltage converters but it's not working as I aspected. Also, I go through some circuits like 
but not worked in my case.
So, please suggest me some idea to do so.
Thank you.....
