Servo operating angle - Electronic Circuits Projects Diagrams Free

ShaunManners · 11th January 2008, 11:21 AM

Hi All,

I am working on a project and bought myself a couple of Hitec servos. I have now built an astable circuit using a 555 timer and controlling it with an input thats between 0 and 10v (10v makes the pulse 2ms and 0v makes it 1ms).

When I tested it, the servo arm didn't move the 180 degrees I was expecting (when no power applied I can move it 180) I had a look at the datasheet for the servo and it says it has an operating angle of "40? one side pulse traveling 400usec"

I am new to servos (as you can probably tell) and I was wondering, what does the "one side pulse" bit mean? I am uncertain as to whether it should travel only 40, or 80. yet while it doesn't travel the full 180 I was expecting, its certainly more than 80.

The other thing is that in the instructions is says a control pulse of between 0.9ms and 2.1ms, if my circuit is giving out 1-2ms do I need to tune it to make the servo move further or is it moving to its fullest extent already.

I appreciate you probably cant answer all of this, but any comments would be welcome!

Cheers
Shaun

**Nigel Goodwin** · 11th January 2008, 11:27 AM

Servos aren't designed to move 180 degrees, probably 90 degrees is about the most?, although by extending the pulses (both less and more) you can get them to exceed their design limits considerably.

ericgibbs · 11th January 2008, 12:58 PM

hi Shaun,
Post a link to the datasheet.

ShaunManners · 11th January 2008, 01:02 PM

Quote:

Originally Posted by Nigel Goodwin

Servos aren't designed to move 180 degrees, probably 90 degrees is about the most?, although by extending the pulses (both less and more) you can get them to exceed their design limits considerably.

Thanks Nigel, so it would seem then that all is working fine. Any ideas about the "one side pulse" bit?

Regards
Shaun

ShaunManners · 11th January 2008, 01:04 PM

Quote:

Originally Posted by ericgibbs

hi Shaun,
Post a link to the datasheet.

Hi Eric,

here it is

http://www.hitecrcd.com/product_file...3/HS5245MG.pdf

Rehards
Shaun

ShaunManners · 11th January 2008, 01:08 PM

I have tried posting two messages with a link to the datasheet, but neither have appeared, and the message that comes up afterwards goes away too quick for me to read! maybe they have to be approved?

the servo is a Hitec HS5245MG.

Regards
Shaun

ericgibbs · 11th January 2008, 01:21 PM

hi,
Here is an extract:

ShaunManners · 11th January 2008, 01:28 PM

Quote:

Originally Posted by ericgibbs

hi,
Here is an extract:

Thanks Eric... as you can see for operation angle it says 40 then says /one side pulse... this is the bit I don't understand

regards
Shaun

ericgibbs · 11th January 2008, 01:30 PM

hi,
This looks a better link:

http://www.servocity.com/html/hs-524...ital_mini.html

This gives an explanation.
http://www.pc-control.co.uk/servo_control.htm

ShaunManners · 11th January 2008, 11:18 PM

Thanks Eric,

It would seem then that it has 90 degree motion range. I will measure it anyway just to be sure. I am also thinking of getting an Oscilloscope to test the pulse from my circuit.

The pc-control article is a good read and explains it well, I am still unsure about what a one side pulse is... but I think I'll just drop that one!

Regards
Shaun

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11th January 2008, 11:21 AM	(permalink)
ShaunManners	Servo operating angle Hi All, I am working on a project and bought myself a couple of Hitec servos. I have now built an astable circuit using a 555 timer and controlling it with an input thats between 0 and 10v (10v makes the pulse 2ms and 0v makes it 1ms). When I tested it, the servo arm didn't move the 180 degrees I was expecting (when no power applied I can move it 180) I had a look at the datasheet for the servo and it says it has an operating angle of "40? one side pulse traveling 400usec" I am new to servos (as you can probably tell) and I was wondering, what does the "one side pulse" bit mean? I am uncertain as to whether it should travel only 40, or 80. yet while it doesn't travel the full 180 I was expecting, its certainly more than 80. The other thing is that in the instructions is says a control pulse of between 0.9ms and 2.1ms, if my circuit is giving out 1-2ms do I need to tune it to make the servo move further or is it moving to its fullest extent already. I appreciate you probably cant answer all of this, but any comments would be welcome! Cheers Shaun

11th January 2008, 11:27 AM	(permalink)
Nigel Goodwin	Servos aren't designed to move 180 degrees, probably 90 degrees is about the most?, although by extending the pulses (both less and more) you can get them to exceed their design limits considerably. __________________ PIC programmer software, and PIC Tutorials at: http://www.winpicprog.co.uk

11th January 2008, 12:58 PM	(permalink)
ericgibbs	hi Shaun, Post a link to the datasheet. __________________ Eric "Good enough is Perfect" PIC tutorials: Gramo's: www.digital-diy.net/ Bill's: www.blueroomelectronics.com/

11th January 2008, 01:08 PM	(permalink)
ShaunManners	I have tried posting two messages with a link to the datasheet, but neither have appeared, and the message that comes up afterwards goes away too quick for me to read! maybe they have to be approved? the servo is a Hitec HS5245MG. Regards Shaun

11th January 2008, 01:21 PM	(permalink)
ericgibbs	hi, Here is an extract: __________________ Eric "Good enough is Perfect" PIC tutorials: Gramo's: www.digital-diy.net/ Bill's: www.blueroomelectronics.com/ Last edited by ericgibbs; 7th July 2008 at 11:23 AM.

11th January 2008, 01:30 PM	(permalink)
ericgibbs	hi, This looks a better link: http://www.servocity.com/html/hs-524...ital_mini.html This gives an explanation. http://www.pc-control.co.uk/servo_control.htm __________________ Eric "Good enough is Perfect" PIC tutorials: Gramo's: www.digital-diy.net/ Bill's: www.blueroomelectronics.com/ Last edited by ericgibbs; 11th January 2008 at 01:33 PM.

11th January 2008, 11:18 PM	(permalink)
ShaunManners	Thanks Eric, It would seem then that it has 90 degree motion range. I will measure it anyway just to be sure. I am also thinking of getting an Oscilloscope to test the pulse from my circuit. The pc-control article is a good read and explains it well, I am still unsure about what a one side pulse is... but I think I'll just drop that one! Regards Shaun