Servos

Robotics and electronics discussion Electronics
1

Good afternoon

I work for an environment agency. we take profiles of lakes. i require our instrument which weighs 0.34kg or 0.75lb) to be lowered into the water and stop for 2 min every meter then continue to a desired depth. i was thinking i could us a servo and Micro Maestro to do this but not sure if you can get it to stop for this length of time and when it gets to the top to wait 24 hour then repeat? can you help?

2

Hello.

The Maestro is capable of running a script to create longer delays. However, the Maestro’s internal clock is not as accurate as those used for general timekeeping. The resonator used for time keeping on the Maestro has a 0.1% tolerance, which means for one day the worst case is a loss or gain of about 90 seconds. You can find more information and an example of long delays in the “Example scripts” section of the user’s guide. You might also find the information in this forum post that David made useful for understanding and getting around the clock drift on the Maestro.

- Grant

3

Thanks Grant for your reply and link. Very helpful

I think I can get round this problem because the data logger that will supply the power will only switch on a time I set and so only powering the Maestro at that time. This brings me on to my next question.

The power supply is 12volts from a battery powered by solar panels. This will be connected to the Maestro which can handle the 12v but I will have a servo connected which needs 6v to run. Could someone point me in the right direction to a step down that will achieve this?

Thanks

4

You can power the servo rails through one of our step-down voltage regulators. This will allow you to step the battery voltage down to 5V. Because servos can draw as much as an amp each, I recommend our D15V70F5S3 or D15V35F5S3.

- Grant

5

Thanks again Grant for your help

As i am new to this please forgive me for this silly question. The voltage coming from the battery can vary from 10 - 18v so I’m assuming I will need a reg between the battery and maestro to keep it between the 5 - 16v maestro range (so I can do this to 12v as from your previous email ok). Then i would need a reg between the maestro and servo to bring it down from 12v to 5v for the servo range. My first question is will the servo run ok on 5v even though it is rated to 6v?

I’m not 100% about amps either. The battery im using is a CELLYTE 12TLG SEALED VRLA Monobloc Gel SOLAR RENEWABLE BATTERY Capacities: 20Ah to 300Ah @ C/100. The maestro is rated to 30ma and the servo 1 amp. From what i read about amps the devices in my arrangement will draw the amps from the battery? Will there be enough amps getting through for the servo. Would i need a fuse in the circuit somewhere? Sorry again for the silly questions and thanks in advance for you time on this.

6

I recommend using one of our lower current step-down voltage regulators like the D24V3F9 or D24V6F9 to supply power for the Maestro’s logic from the battery, and then use one of the two regulators I recommended in my previous post to supply power to the servo power rail on the Maestro from the battery.

Most servos are designed to work for the common nominal battery voltages of 4.8V and 6V, and should be fine operating at 5V. However, I would check your servo to be sure this is the case. Please note, that when operating a servo at a lower voltage you will probably experience a small amount of performance loss, like less torque.

That battery looks pretty robust and should be able to deliver more than enough current for your application. A fuse is probably not necessary, but if you want to add extra protection, you can use one.

- Grant

7

Were you able to find the solution? Even I want to drop down the voltage generated from solar panels so please post suitable reply.