Enable Disable a resistor

Hi there, i want to apply a resistor via arduino.

If i do it by hand i just connect / disconnect 5V or GND to one end of the resistor. How can this be done by arduino ? I searched alot but i think my question is too stupid.

Thank's alot for your help

Greetings

What will the resistor be connected to? You could use a relay, transistor, MOS FET, opto isolator.

The resistor is connected parallel to a video line to dim it down or not.

In off state the resistor should not be connented to ground or 5 volts that's my problem.

At what rate will you be switching the resistor? You can try each method suggested and see if it/they meet your requirement.

Ok think i got it ;) Thanks alot !

What is the signal voltage (min/max) and what is the resistor value? Seeing that you've already tried manual connections and assuming the signal is within safe operating range of the Arduino pin, you could try using an Arduino pin to programmatically control 3 states:

With the pin configured as an input, this would be your disconnected state (high impedance). With the pin configured as an output, you could set it high (5V) or low (0V).

If the signal is compatible with PWM, you could have 256 different settings to dim the video.

LarryD: You forgot one. You could use the Arduino to control a digital Pot.

SPDT relay will do what you are looking for.

NO to resistor NC to bypass the resistor C to wherever it needs to go.

With video you might have to take care about the capacitance across the switching device.

. . . and what sort of video? Composite, RGB, HDMI, etc.?

Russell.

74HC4066