Like a potentiometers but controlled digitally

Okay dumb question (since I'm not a complete noob)

I have a servo on its own power supply (raw port of the arduino)

I need to be able to turn on and off the power to the servo using the arduino.

I'm thinking about putting a resistor to the servo power line, then have something with a variable resistance (like a potentiometers) that control with the arduino (thus making resistance higher or lower than the resistor to the servo)

What electronic part am I looking for?

A transistor?

ya thats what I was thinking, I use them for the PSU to the servo, would I need another??

For this kind of ON/OFF switches, MOSFET might be even better as they are voltage controlled and you wouldn't need to worry about the current capacities of the output pins.

hmmm.....I thought transistors and MOSFET were pretty much the same thing....

I have one MOSFET that convers the raw 9v to 5v....

I have an electronic and ceramic capacitor to help regulate.....

Guess I need the power from that to go to another transistor? and control it with another pin?

Relay?

relay transistor fet, can all switch a load on or off, they all have unique operating stats and choosing what YOU need really depends on what your trying to do with it

ie a 2222 transistor would be overkill to switch a led, but would be "insta-smoked" trying to switch a average sized light bulb

Ya thats my concern right now.

My servo is drawing 5v and maybe up to 800amps (the max the wall wart is rated).

Would something like that blow a transistor? Would I be safer with a relay switch?

Thanks!

My servo is drawing 5v and maybe up to 800amps (the max the wall wart is rated).

Imagines an 800A wallwart... :o

I think you mean 800 mA (milliamps)...

:)

haha, you are incorrect it is a 800A!!!! It says so on the wall wart!!

(j/king you are right)

Okay re-post my fixed question?

My servo is drawing 5v and maybe up to 800mA (the max the wall wart is rated).

Would something like that blow a transistor? Would I be safer with a relay switch?

Would something like that blow a transistor? Would I be safer with a relay switch?

Depending on the load on the servo, it might draw more than 800 mA. You should measure this first. Do this by having the servo turn, while trying to stall the output shaft (depending on the size of the servo, this might not be possible, or the servo might be damaged - use care) while you measure the current by putting the meter in between the positive voltage pin of the servo and the servo's power source.

Once you have done that, you can then size the transistor, FET, -or- relay (relays can have problems too if you don't size them right) to the load of the servo. Let us know what you measure for the current, then we possibly can help you further.

:)

My servo is drawing 5v and maybe up to 800mA (the max the wall wart is rated).

Would something like that blow a transistor?

That depends on the specific transistor you select, they come in all voltage and current ratings. It should be no problem finding a transistor rated at say a couple of amps max current flow. Now to control flow from that 800 amp wall wart might take a while looking through catalogs and datasheets. :wink: