Hello Klaus
OK, let me try to explain a little bit of what I hope to achieve.
Lets start with the
Master.
I need to send data and power along 2 wires (fig 8 wire) to 1 or many slaves. The master device data is at TTL level but it's connected to a mosfet type device with a VCC of 20vdc, so the data level is between 0-20vdc. The data is actually inverted so when the data is at 0v, the mosfet level is actually at 20vdc. The reason for 20 volts is so if the length of fig 8 cable is 500 metres or more, the voltage drop won't matter because if it's at 10vdc then 10vdc is still considered a "high" compared to zero volts being a low.
The other reason for the inverted data is because I want to avoid using batteries ( rechargeable ) in each of the slaves ( parasitic power )
When there's no data the 20vdc level is used to power up all the slaves.
The
slave device.
Has no internal batteries.
Each slave is hooked up in parallel, polarity doesn't matter because of the bridge rectifier.
The 20vdc is used to power a 5v regulator which powers most of the circuitry. There's a super cap of 1 farad to assist when there's data present.
The 20vdc is also connected to a dc - dc step up module to charge up a 10,000uf/25v capacitor at 20vdc.
Even if there is a voltage drop from 20vdc to 10vdc ( really long cable or lots of slaves connected ) the entire electronics will still work.
So of course in the slave I need to reduce the data/VCC line of 10-20vdc to 5vdc
Bi directional data would be nice but I need to try to keep it as simple as possible, so one way data for me will be fine.
There's a bit more to it but this is as simply as I can explain it.