I’m having Power Issues and need some help?
Products I’m using
1 Mini Maestro 12
2 Hitec HS-35HD servos
5 Hitec HS-53 servos
2 Hitec HS-311 servos
1 Hitec HS-40 servo
The HS-35HD operates exclusively with 4 Nicad cells ( 4.8 volt ). which is where the problem lies. They are the only Servo small enough to fit in this location with sufficient torque ratings. 50% of the time they are holding back a spring actuated mount which means they are constantly drawing current to hold their position which they do just fine with fresh batters. But with 10 Servos drawing power at least 2 at a time, sometimes 5 at once the Batters die Very Quickly.
2nd problem is as the power weakens the servos move slower and it throws off the timing of the sequencing.
My Question
Can the Hitec HS-35HD servos be powered with a wall wart or some other type power supply? If so which one and where do I get it?
If not is their a way to power the board and the other Servos from a wall wart and power only the 2 HS-35HD’s from the batters?
Note: The whole thing is stationary so if their is any way to eliminate the need to use batteries I would like to do so.
Thanks
David
In principle you can use a 5 to 6 volt power supply for all the servos. The supply should be capable of providing at least 1 ampere per servo, for as many servos as will be moving at once. From what you stated, you will need a 5V 5 ampere power supply at the very least.
You can get power bricks for laptops and monitors, capable of several amperes, quite cheaply at thrift stores. The voltages are usually higher than 6 volts, but you could use Pololu step down voltage regulators to bring it down to servo levels. One of these should work for up to 5 servos, but you may need to run two regulators from one power brick.
If you go that way, the current draw from the power brick will be significantly less than the total current draw from the servos, due to switching regulator action.
Keeping the servo’s under power may reduce lifetime too.
Maybe a small change in your construction may help. If you kan make a sort of knee construction you can save a lot of power and servo life. If the servo arm is in line with the pushrod under load there is no torque needed. You may look into mechanical retracts for RC planes for this type of construction. A spiral cam may just do the same.
Do you really need the spring? The servo will do the movement for you.
The HS-35HD is as big of a servo I can fit in the location. Believe me if I could fit something bigger I would. I actually had to sand down the cases on them to make them fit. I can’t lighten the spring pressure any more than it is now. Like I said the 2 servos working in tandem are doing the job just fine. Its a prolonged power issue or should I say the lack there of that I’m dealing with. At the rate i’m burning through freshly charged new batteries I will need to change them out every 35 to 40 minutes or about 12 to 15 times a day.
I guess I’m going to get a regulated 5v 5amp power supply and give it a try. hopefully the 0.2v difference will not fry them. I’ve re worked the sequencing so only 3 servos will move at one time for the most part, 5 at once will happen only twice in each 6 minute animation sequence.
David
