Saving power by cutting servo supply

Hi all I'm currently working on a project which requires a pro mini to turn a servo twice a day, and both will run off batteries. Now obviously it's important to conserve power when running off batteries, and (according to my multimeter)when the servo is idle, it consumes approx. 6mA. Therefore I thought it would be a good idea to use a transistor or relay to turn on the power supply to the servo only when it is needed. 5v pro mini, controlling a relay/transistor to supply 6v to the servo. Just wondering whether anyone had any suggestions for the cheapest relay/transistor for the job. Thanks very much in advance :)

Google “Sparkfun relay”

For cheap it's hard to beat this one on E-bay:

http://www.ebay.com/itm/New-1-Channel-H-L-Level-Triger-Optocoupler-Relay-Module-for-Arduino-5V-/221409246814?pt=LH_DefaultDomain_0&hash=item338d04fe5e

Don't servo's tend to reposition them selves when powered up with no control signals? May want to check out behavior with just a toggle switch to start, see if you will have any unexpected behavior.

CrossRoads: Don't servo's tend to reposition them selves when powered up with no control signals? May want to check out behavior with just a toggle switch to start, see if you will have any unexpected behavior.

A 4k7 resistor between signal and ground might stop this if it is a problem.

...R

No, I was thinking the lack of the PWM type signal when power came up, or getting in sync with it again, might cause some unexpected movement or jitter or something.

Removing power from a servo will remove all torque force from the servo and only leave gear friction to resist any load changes. Also removing power with a servo output signal still active will cause 'phantom' current to flow via the output pin if the arduino is still powered up. So detach servo command and a digitalWrite low should be performed. In all likelyhood when re-powering up the servo and re-attaching the servo library will mostly like cause a jitter or worst.

The various servo conditions described probably can be easily tested to see just what happens with the servo. Possibly a future project.

retrolefty: For cheap it's hard to beat this one on E-bay:

http://www.ebay.com/itm/New-1-Channel-H-L-Level-Triger-Optocoupler-Relay-Module-for-Arduino-5V-/221409246814?pt=LH_DefaultDomain_0&hash=item338d04fe5e

Thanks, but just wondering, obviously VCC on the relay module goes to arduino 5v, when the relay isn't doing anything is it still sucking power from the arduino?

Musicboy:

retrolefty: For cheap it's hard to beat this one on E-bay:

http://www.ebay.com/itm/New-1-Channel-H-L-Level-Triger-Optocoupler-Relay-Module-for-Arduino-5V-/221409246814?pt=LH_DefaultDomain_0&hash=item338d04fe5e

Thanks, but just wondering, obviously VCC on the relay module goes to arduino 5v, when the relay isn't doing anything is it still sucking power from the arduino?

No