triple DC voltage switch

Hi,
I would like to find someone who could design the circuit and help me manufacture the pcb.
This is what I am looking for in layman's terms:

We have 1 input line (A) where voltage input can be 0 VDC or 5 to 36 VDC
We have an input voltage (DC) that can be 10 to 26 VDC to power the circuit
We have 1 output line (AA)
We would like that:
1) when there is 0 to 5 VDC in the input line (A) that the output line (AA) = 0 VDC
2) when there is a voltage > 5DVC in the input line (A) that the output line (AA) voltage = the input voltage (DC)

Once this is solved our real need is for triple version of this circuit:
1 input voltage (DC)
3 input lines and 3 output lines: (A) => (AA), (B) => (BB) and (C) => (CC)

Practical use
The Voltage (DC) will be produced by truck’s batteries either 12 VDC or 24 VDC
The input voltage for lines A to C will be produced from parts of the same truck (ignition switch, alternator excitation terminal, other similar).

NB: this circuit will be working 365 days per year


Thanks for your help.

Yves

2 questions left

There's two important question to be answered before it's worth start thinking out a solution:

1. Is there possible that under some circumstances the input voltage will swing around 5V with some ripple?
2. How much current do you need? (need for a relay or not)

Hi Grossel,

1) Input voltages are sourced as follows:
A: Source ignition switch. Generaly the ignition switch will output voltage when moved from position Off to On. In position On it will output the truck's voltage i.e. what I call (DC).
B: Source Excitation terminal of the truck's alternator. When the engine is fired, this terminal will voltage wil go from 0 VDC to whatever is truck's voltage (12 or 24 VDC). Depending on the age of the alternator the building up of the voltage can be slow (30 secs) so yes you can have during a few seconds a voltage out put around 5 VDC
C: Same as ignition no voltage built up.

2) Current
For the AA, BB or CC response all is needed is to feed the truck's voltage (DC) when voltage in A, B or C is above 5 VDC, current is not important.

Regards

Yves

Current is not important?
I assumen that means you want to just have a signal output.

I have basic schematics for both a schmitt-trigger and voltage folower.
Now you need them connected together so that it works as you spesified. Too tired to think right now, I see if I can draw something basic tomorrow

Hi Grossel,

This is correct I just need a response signal output from AA, BB or CC.

Many thanks for your help.

Yves

Yves,

Here is the basic idea. The trip point is controlled to better than 0.5%. It has a little hysteresis to prevent chattering. It has an input resistance of ~20K. It can source a few 10s of mA when it switches on. It works at 10 and 26V. I haven't worried about the glitches likely to be found in automotive applications. Parts cost less than $1.