Great New Miniature Servo

[Subculture]

In a nutshell, yes.

[He Who Shall Not Be Named]

No it's a normal rectifier diode. Have a read of this-

http://www.kpsec.freeuk.com/components/diode.htm

You mean that by using a normal type diode we're looking for the normal .7-volt drop across the forward side of the diode to get the 5-volt down to a safer 4.3-volt?

David,

[Subculture]

I contacted Aroosh at Sombra Labs regarding this potential problem and here are his commentrs.

The operating voltage range should be fine, after all the servo bus on the SL-8 just re-supplies the battery voltage to the connected devices. As long as this new receiver conforms to the industry standard PWM input, it should work fine. If you're concerned, get one sample to test out before ordering a large quantity. I've actually never received a word regarding issues with servos with our receivers.

Regards,

Aroosh Elahi
Sombra Labs Inc.

Most receivers will happily accept a 6 volt feed, and will pass that onto the the servos, most of which will be okay with 6 volts but there are quite a few which won't, not to mention any other devices hooked up, especially those which use microcontrollers without their own voltage regulation (try hooking up a PIC microcontroller to 6 volts and see how hot it gets, really quickly!)

[Subculture]

No it's a normal rectifier diode. Have a read of this-

http://www.kpsec.freeuk.com/components/diode.htm

[He Who Shall Not Be Named]

A simple method to drop the voltage (if this proves to be a problem) would be to wire in a 4001 diode inline with the positive power wire. This should drop the voltage by about 0.7v and bring the 5 volt very close to single cell lipo voltage.

We talking a Zener type diode here, Andy?

David,

[Kazzer]

I contacted Aroosh at Sombra Labs regarding this potential problem and here are his commentrs.

The operating voltage range should be fine, after all the servo bus on the SL-8 just re-supplies the battery voltage to the connected devices. As long as this new receiver conforms to the industry standard PWM input, it should work fine. If you're concerned, get one sample to test out before ordering a large quantity. I've actually never received a word regarding issues with servos with our receivers.

Regards,

Aroosh Elahi
Sombra Labs Inc.

[Subculture]

A simple method to drop the voltage (if this proves to be a problem) would be to wire in a 4001 diode inline with the positive power wire. This should drop the voltage by about 0.7v and bring the 5 volt very close to single cell lipo voltage.

[He Who Shall Not Be Named]

The manufacturer says they'll operate to 5 volts. Samples en route to The Cave for testing!

Thank God! You scared me there for awhile, Andy.

Don't want to have to make a special voltage dropping circuit to cram in there just to protect the servos from the receiver bus voltage.

I do appreciate the heads-up thinking on that issue though.

You're right, of course: those things were initially designed for ultra-light, small, aircraft employing a single-cell battery and might indeed have not been beefed up to take the full range of receiver operating voltages -- good thing the manufacturer made these things so versatile in that department. If Mike and I had plowed ahead without considering that (which was exactly what was happening till your above post), and if the servo could not dine on a normal receiver bus voltage without frying, then we would have wound up pouring Mikes money down a rat-hole and wasting my very valuable time.

Good thinking, Andy. Your input is always appreciated ... helps keep me honest and on my toes, and Mike out of the poor-house.

David,

[Subculture]

Hmmmm. I would suspect the control circuitry could take it, as it should be regulated probably to 3 or 3.3 volts. The motor will be a different kettle of fish however. Those motors are pager motors, used for the vibrating mode on mobiles etc.

They're designed to run on a single lithium battery, which is 4.2 volts max. Start running them at 5 volts and I think it will shorten the lifespan.

[Kazzer]

If you try and run these from a 5 volt receiver buss you'll let the magic smoke out of them.

The manufacturer says they'll operate to 5 volts. Samples en route to The Cave for testing!

[Slats]

Getting back to my other question Mike, can you please give me some measurements on the motor itself (Diameter and case length)?

I have a small job that I could cannibalise the motor for.

Thanks
J

[He Who Shall Not Be Named]

As is your Type-214, Jim ... still in the rotation, I assure you.

David,

[Outrider]

When I look at the servos for underwater use, I think of the 1:72 Fine Molds Ko-hyoteki (Target Type A) submarines. I think that it's unlikely that we'll ever see a D&E sub driver made that small, but I'd love to see that little beast (the Target Type A) in the water with other 1:72 subs. I'm just back from Pearl Harbor and have studied up on the Japanese use of small subs in the 1941 attack. Two of the five small subs made it in to the harbor and fired weapons. One of these was sunk after weapons release, but another seems to have hit the Oklahoma and then made it to a safe location in the West Loch and scuttled. The Ko-hyoteki crews must've had some very big cajones to have entered Pearl Harbor with only one very constrained way in or out.

Back to the point of the thread, if we ever see that 1:72 Fine Molds kit as an RC, it will likely use these servos.

As a bonus, David teases us again with the Revell Type 212! But at least we know it's still "on the list" and, happily it's still available from Revell. The D&E 1:96 GRP Type 212 will probably prove more durable in the long run, but the polystyrene kit is probably going to be easier for most mere mortals to assemble.

[Subculture]

For their size and weight these are torquey little servos, as they're based on a jack screw. But they're no match for the 2.5-3 gram servos. These are really designed for very small indoor flyers where weight is paramount and the loss of a couple of grams can mean an AUW reduction of 10%.

Also bear in mind that these are designed to run from a single lithium cell- hence the 3.7v operating voltage. If you try and run these from a 5 volt receiver buss you'll let the magic smoke out of them.

[Slats]

Thanks David, that is a nice piece of innovation.
J