DPRG mailing list archives: [DPRG] Pittman GM8712 stats

Sat Sep 8 09:55:27 CDT 2001

David,

A trick I learned. The tye wraps you used in your picture are incremental "clicks". They have detents built in. These hold better than the other "linear: type but the linear type will let you make micro adjustments. If you projects slips too much, use a linear tye wrap. One with no little grooves on the surface.

Regards,
Bob

-----Original Message-----
>From:	David P. Anderson [SMTP:dpa at io.isem.smu.edu]
Sent:	Tuesday, September 04, 2001 1:52 PM
To:	dprglist at dprg.org
Cc:	seattlerobotics at yahoogroups.com
Subject:	[DPRG] Pittman GM8712  stats

Howdy

I made some measurements this weeked with the single channel home-brew
encoder on a Pittman GM8712 gearhead motor.  I used an encoder wheel
with 20 segments: 20 ticks per motor revolution, as per:

ftp://www.geology.smu.edu/pub/users/dpa/robo/pittman/home_brew_enc_01.jpg

and

ftp://www.geology.smu.edu/pub/users/dpa/robo/pittman/home_brew_enc_02.jpg

I verified and adjusted the sensor spacing with a scope, then connected
it to an M.I.T. 6.270 board (HC11) and used the TIC3 interrupt to
count encoder ticks per second, which I printed on the LCD.  I used a
DC bench supply to power the motor, with a multimeter to measure the
voltage and current.  Here's what I got:

---------------------------------------------------------------------
motor_speed.txt
03 Sept 01
dpa

Pittman GM8712 with 20 segment encoder
No-load measurements

Voltage	Current	 Ticks	Motor	Gearhead
  V  	 A	per/sec	 RPM	 RPM

 19.1 	1.4 	2641	7941	132
 15.0	1.4	2050	6156	102
 12.5	1.3	1658	4980	 82
 10.0	1.2	1302	3906	 65
  7.5	1.15	936	2808	 46
  5.0	1.0	570	1710	 28
  4.0	1.0	434	1302	 21
  3.0	0.9	288	 864	 14
  2.0	0.8	156	 468	  7
  1.5	0.75	 84	 252	  4
  1.2	0.75	 37	 111	  1
  1.1	0.75	  0	   0	  0

---------------------------------------------------------------------

regards,
dpa

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