I am totally stuck now!
I try to control a car media system, that kind that is controlled by a steering wheel switch.
The switch i just a bunch of different resistances, ranging from aprox. 80 - 4000 Ohms.
I have a analog output from my control circuit, 0-10V (max 1mA)
I've tried with different FET's and transistors to simulate the different resistances (eg. current), but I've only failed so far.
And to tell the truth, I'm not a very good circuit designer...
Do any one have a good idea on how to solve this?
I've found out that the input stage on the media system is a resistor ladder with a pullup of 340 Ohm to 5V and a pulldown of 51 kOhm to GND.
So effectively I just have to control a current of 1mA to 12mA to simulate the buttons, but how can I do this?
I try to control a car media system, that kind that is controlled by a steering wheel switch.
The switch i just a bunch of different resistances, ranging from aprox. 80 - 4000 Ohms.
I have a analog output from my control circuit, 0-10V (max 1mA)
I've tried with different FET's and transistors to simulate the different resistances (eg. current), but I've only failed so far.
And to tell the truth, I'm not a very good circuit designer...
Do any one have a good idea on how to solve this?
I've found out that the input stage on the media system is a resistor ladder with a pullup of 340 Ohm to 5V and a pulldown of 51 kOhm to GND.
So effectively I just have to control a current of 1mA to 12mA to simulate the buttons, but how can I do this?