DC Permanent Magnet Motors

© Brooke Clarke 2013 - 2016

    YouTube Videos
    Testing DC PM Motors (separate Web page)
Basic Theory
Mabuchi Model Numbers
    1.5 - 3 Volt Toy Motor
    Silly Happy Crazy Birthday Card Motor
    Wireless Power Transfer
Pulleys & Gears
    80/20 Products - EF101
Electronic Speed Controls (ESC) & Related Controls
Lego Wheels, Tires, Couplers & Motors
Tamiya RC
Heli-Max RC Quad Helicopter w/TV Camera
FPV Cameras
Solar Showcase 360° Turntable


On my web pages there are a number of antique DC and AC motors.  I sometimes get technical questions about them.  I'm also interested in very efficient electrical circuits, like the Joule Thief that can light a LED with a dead battery or Miller Solar Engine (MSE) that can be used to power a small DC motor.

DC PM motors make use of magnets and testing them requires special flywheels.

Basic Theory

June 2015 - I'm interested in the DC PM motors with a 3.17mm (1/8") shaft because they are reasonably priced ($3 to $11) and are commonly used in RC vehicles that are about 1 foot in size.  The shaft diameter of a motor is related to it's power output, for 1/8" shafts that amounts to about 50 to 200 Watts (746 Watts is 1 horsepower).
For a given shaft size the armature and frame magnetics will be about the same.  The main variation is in what size wire is used to wind the armature and that relates to how many turns will fit.

The best short paper on permanent magnet DC motors is "Characteristics of DC Motors.pdf" by Rutgers Prof. Dunbar P. Birnie.

Mabuchi Model Numbers

Mabuchi Motors - Technical Guide - Part Number List
Decoding Mabuchi part numbers: L1L2-N1N2N3L3L4-N4N5TTTT

L1 Shape: Flat (F), Round (R), Square (S)
L2 Brush: Metal: (A, E), Precious Metal (F), Carbon (C, H, K, S, T, Z)
N1 Armature Diameter: small lto large (J, K, M, N, 1, 2, 3, 4, 5, 6, 7, 8)
N2 Housing Length code:
N3 Number of Armature Poles: 3 (0), 5 (5), 6 (6), 7 (7), 8 (8), 10 (A), 12 (B)
L3 Magnet: C Isotropic (R), Ring Isotropic (T), Anisotropic or Rare-Earth (P, S, V, W), Rubber (C, E, F)
L4 Custom Design: Encoder (W)
N4  wire diameter tenth of mm: If number tenths of mm, if letter A = 1mm
N5  wire diameter hundredths of mm: 0.01mm (1), 0.05mm (D), 0.055mm (Z)
TTT Turns per slot: might be 2, 3 or 4 digits.

Stall Torque and Stall Current are proportional to 1/(wire_diameter^2) - I tried this on some data and at first glance I don't see the correlation.
Pwr out (Watts) = [N (rpm) * T (mN-m)]/9550

The 4 cardinal performance points are: No load RPM and Current, Stall Torque and Current.


K is the relationship between applied voltage (Volts) and the speed in radians (Wiki) per second (symbol w).  Since speed is commonly given as Revolutions per Minute that needs to get converted.
    RPM / 60 = Rev Per Second (RPS).
    RPS * 2 * PI = Radians per second
    For example a For the Mabuchi RS-545SH: motor that turns 6800 RPM at 12 Volts has w = 2* PI * 6800 / 60 = 712 radians per second.

The electrical circuit looks like a constant voltage drive, routed through the internal resistance of the armature to a virtual battery whose back EMF (Vbemf) is determined by the motor RPM. 
Vbemf = K * 2* PI* Rev/Sec
K = Voltage / (radians per sec) , = 12 / 712 = 0.01685

The electrical equation is:
Vdrive = I * Rinternal +Ebemf

Tstall = K * V / R

"Turns" refers to the number of times a wire is wound around one of the poles of the armature.
For example the Gilbert DC Motor (used in Erector Sets) has a 3-pole armature and each pole maybe a couple dozen turns.
The force on a wire in a magnetic filed depends on the magnetic field strength and the current in the wire.  Since the magnetic field is fixed for a given motor the torque depends on the number of turns and the current.

For example

The Mabuchi RS-550PC (see below) we know at 7.2 V drive the no load speed is supposed to be 13500 RPM.
So K = 2 * PI * 13500 / 60 = 1414

The stall torque is given as 3700 g-cm with a current of 83 Amps.  The back EMF at stall is zero, so
R = V / I = 7.2 V / 83A = 0.0867 or 86.7 milli Ohms.

Measuring R Directly

Note:  A direct measurement of R is very difficult.  If a DC measurement is made there will be errors because any dissimilar metals will generate DC voltages that are unknown, see my web page on Kelvin (4-wire) resistance measurements.  The 50 milli Ohm limit of the HP 34401 DMM is very close to the resistance of the RS-550PC motor.

A direct measurement using an AC test method will have an error because of the inductance of the windings.  See the HP 4328 Milliohmmetere web page for an example.

It may be possible to make a swept frequency impedance measurement using the HP 4395A and by fitting the data to an equivalent circuit separate the real and imaginary parts.  This may also be possible using an LCR meter that has a series equivalent circuit representation, like the HP 4274 & HP 4275 LCR meters.

Back EMF (Wiki)

When the armature is stalled there is no back EMF, but as soon as the armature is turning it's generating a back EMF that subtracts from the applied voltage thus reducing the armature current. Vbatt -Vemf = Iarm * Rarm.

Note if the motor has it's shaft turned by an external torque then it will act as a generator and the voltage is exactly the same as the back EMF (assuming the load resistance is very high, i.e. not using the generator to power something, just using a high impedance meter to read the voltage).

Back EMF [Volts] is proportional to (magnetic field strength[Webers]) * (total number of wires[no units]) * (rotational speed[RPM]) / 60 [convert RPM to RevPerSec]

Note:  If the power circuit to the motor is opened and a high input impedance voltmeter is across the motor terminals it will read the back EMF.
Tried this on an RS-555 motor where the supply was set to 18.0 Volts.  With the power applied the DMM reads 18.0 volts and when the power is disconnected the voltmeter reads about 17.9 Volts and as the motor spins down the voltage drops.

Stall Current

For the Mabuchi RS-545SH:
Nominal spec: 6800 RPM @ 12 Volts, K= 0.01685
The no load current in in the range 0.25 to 0.3 Amp, Torque (no load) = 0.25A * 0.001765 Volts/RPM =

No Load

The motor resistance is about 2.5 Ohms including the wires from the power supply.

Note: A key thing about these is that they can produce a lot of torque when the shaft is stalled.  Internal Combustion Engines (ICE) need to be running at some speed in order to produce torque.  This is why Diesel Electric Locomotives are so popular, i.e. they have a lot of torque at zero speed.  BUT . . . a lot of attention needs to be paid to cooling the motor since overheating can easily burn it out.

Starting Current

In June 2015 I got some RS-775 type motors that have a 5.0mm shaft diameter to work with a family of flywheel/pulleys.  When powered by an HP/Agilent/Keysight E3617A power supply (0 to 60 Volts at up to 1 Amp) the motors will not start spinning.  But on power supply, like the HP 6038A that can supply higher currents the motor spins up.

Self Starting 

A 2-pole motor may not start when power is applied and will turn in either direction depending on the direction of the initial manual spin.  Motors with 3 or more poles will self start and run in the same direction for the same input polarity.


Efficiency is a measure of the power output compared to the power input.
When a motor is running with no load it has zero efficiency because there's no useful power out.  So the lower the power consumed when the motor is running at no load the better.

Note:  At "no load" there really is a small load because of bearing friction and wind loss.  There are some Youtube videos where the presenter was proud of the high power consumed by his motor when running at "no load", that's a big mistake.

May of the YouTube home built DC motors that claim "over unity" or "zero point energy" are being evaluated on their electrical input power and electrical output power and the mechanical output power is never evaluated.  One of the presenters went to some effort to describe how to make a small dynamometer but never showed it being used on any of his "motors".  So, the so called "motors" are not really motors but rather DC to DC converters and so are misnamed "motors".  Note that measuring electrical power when the current is either DC or a sine wave is straight forward, but when it's a more complex waveform it's difficult to make power measurements.  Many of these "motors" can be seen as works of dynamic art and are fun to look at when they are running.


Pager Motor

This Miller Solar Engine (MSE) circuit runs the motor for about 10 seconds.  The times vary depending on how bright the light is.
On a cloudy day it might be six minutes between runs of 6 seconds, and in direct noon sun it might be 11 second runs every 10 seconds.
The circuit works by the solar panel (the back of the panel has the MSE ciruict shown in the photo) charges up a 0.33F super cap and when the 1371 gets to it's trip voltage a pin is grounded turning on a transistor that connects the super cap to the motor.  The 1371 has it's own capacitor with isolation diode so that it will remain on even after the super cap voltage goes below the trip point.

I expect with some glue circuitry a number of these can be connected in series to provide higher voltages and larger value super caps can be used.

Solarbotics.com SCC3733-MSE Solar Engine with pager

Maxon A-max

26mm dix x 57mm overall
Motor body length: 44.65mm
2.97mm dia shaft with flat x 10.73mm long
Six threaded holes on shaft end, size & location TBD.

Motor starts to turn at 0.07V and draws 12ma.




Maxon A-max Permanent Magnet DC Motor
17.4 dia?

Maxon makes some very high end motors with much better specifications than you get from a pager motor.  Instead of the under a dollar that a new pager motor costs, these go for about $100 each new and are not often on the surplus market.  Supposed to have very low no load power and be very efficient.

Mabuchi RS-550PC

Mabuchi RS-550PC permenant magnet DC carbon brush motor & DT2234A+ digital Optical tachometer
Aluminum foil and painters blue tape wrapped around gear for tachometer.
                  RS-550PC permenant magnet DC carbon brush motor &
                  DT2234A+ digital Optical tachometer
Two RS-550PC Motors
coupled for measurements
                  Mabuchi RS-550PC Motors coupled for measurements
Blue tape on coupling to stop reflections, triangle is reflective strip.
Dual motor test done using:
HP 6038A 0 - 60 V  0 - 10 A Power Supply
Two RS-550PC Motors coupled so No. 1 is motor and No. 2 is generator
High Power Load from Tamaya Grasshopper RC car Mechanical Speed Control
Optical Digital Tachometer DT2234A+

Volts In Amps In Watts In RPM Volts Out Amps Out Watts Out R In R Load
3 0.64 1.9 869 1.96 0   4.7  
1.25 3.8 476 0.22 0.037 0.008 2.4 5.8
4 0.74 3.0 1295 2.96 0   5.4  
1.54 6.2 721 0.32 0.048 0.015 2.6 6.6
5 0.73 3.7 1661 3.75 0   6.8  
1.80 9.0 895 0.42 0.043 0.018 2.8 9.7
6 0.77 4.6 2075 4.70 0   7.8  
2.09 12.5 1112 0.61 0.042 0.025 2.9 14.4
7 0.61 4.3 2589 5.86 0   11.5  
2.33 16.3 1354 0.64 0.042 0.027 3.0 15.2
8 0.43 3.4 3014 6.80 0   18.6  
2.38 19.0 1609 0.71 0.055 0.039 3.4 12.9
9 0.44 4.0 3516 7.92 0   20.5  
2.64 23.8 1946 0.85 0.062 0.053 3.4 13.7
10 0.44 4.4 4086 9.06 0   22.7  
2.85 28.5 2202 0.90 0.074 0.067 3.5 12.2
11 0.47 5.2 4468 10.06 0   23.4  
3.15 34.7 2432 1.01 0.06 0.061 3.5 16.8
12 0.56 6.8 4954 11.05 0   21.3  
3.42 41.0 2652 1.08 0.084 0.091 3.5 12.9

RPM = 390.51 * Vin with motor #2 as open circuit load.

This is a carbon brush permanent magnet DC motor (Data sheet).
Some specs:
Operating Voltage 6.0 - 9.6, Nominal 7.2 VDC
No Load Speed 15,300 RPM @ 1.4 Amps
At Max Efficiency: 13, 540 RPM, 10.8 Amp 41.7 mN*m, 425 g*cm, 59.1 Watts
Stall Torque 363 mN*m, 3700 g*cm @ 83 Amp
25mm diameter x 75mm overall length
3.17mm OD x 8.7mm shaft.

2x M3 mth holes 24.3mm apart?

Mabuchi RS-555PH-3255

Rated voltage - 12 volts DC
No load speed 5500 RPM
No load current - 360 ma.
Rated load current 2.45 amps
Rated load torque - 380.3 gr/cm
Stall torque - 1360.3 gr/cm
Stall current - 11.8 amps

Total length  - 3 1/4" with shaft and contacts
Motor body  - 2 1/4"
Diameter -  1 3/8"  
Shaft length - 1/2" long, flat one side
Shaft diameter  - 1/8"

Electronic Gold Mine Motors

Speed Regulated Prec DC Motor
Electronic Gold
                    Mine G16126 DC PM Motor

cass thrd
Bertsch Micro Motor
Electronic Gold
                    Mine G16260 DC PM Motor

RF-520C-17410 Efficient DC Motor
12V   5500rpm
Electronic Gold
                    Mine G16280 DC PM Motor 32.88
Enclosed 12VDC Motor
Electronic Gold
                    Mine G16580 DC PM Motor 28.55
G17687 2 Motor Drive CD Head Assy
Two motors:

Spindle: BCD3B, 05UD8X31A
24.0 DIA X 11.0
SHFT: 1.96 DIA x 7.7
6xcass thrd

Head traverse: BDH3B, 06.8x22a
25.84 DIA X 9.91

x 2.95
Electronic Gold
                    Mine G17687 DC PM Motor
Spindle & Head Assembly motors
CD Spindle
                    & head assy drive motors
Optical Assembly
The DC motor does the coarse track positioning
and the Electromagnetic motor does the fine
positioning (movement parallel to rod).
It's also possible to move the lens
up and down for focus.
CD-ROM Drive
                    Optical Head Assembly
Mirrors in Optical Assembly
                    Optical head assembly mirrors
1. Laser Dide
2. half silvered mirror
3. 100% silvered mirror
4.  Lens on black plastic frame
5.  photo diode

Super Efficient Solar Motor
6V. M9I60U22-1 CW
Sanko Electric Co. Ltd.
Electronic Gold
                    Mine G18050 DC PM Motor 31.53
Our Best DC Motor Assortment
1 ea: "RF-520C-17410" G16280
1 ea:  "CDX9"  G?
1ea:  "MH415A"
1ea: "SDC2L"
1ea: "30011 Johnson 371421"
Electronic Gold
                    Mine G18186 DC PM Motor

Very Efficient Pancake Motor w/Pulley
Cassette motor?
Electronic Gold
                    Mine G18524 DC PM Motor 24.93

cass thrd
Massive 12VDC Motor
Electronic Gold
                    Mine G18945 DC PM Motor 44.64
Heavy Duty DC Motor
Electronic Gold
                    Mine G18984 DC PM Motor 37.41
Micor Pancake Vibrator Motor

Might be brushelss, Allegro A1442 - AN205049

Microchip TD6505 is a 3-phase fan controller with PWM input.
Electronic Gold
                    Mine G19249 DC PM Motor

Wild Rat/Mouse

3196580 Toy vehicle having resilient supports and self-contained drive means, Robert G Rakestraw, July 26, 1965, 446/484 74/84R 180/7.1 446/3 -

3530617 Vibration driven vehicle, Earle M Halvorson, Sep 29, 1970,
446/484 74/84S 180/7.1 446/3 446/230 0
Electronic Gold
                    Mine 19306 DC PM Motor Wild Rat/Mouse

Pager Motor Assortment (3)
Electronic Gold
                    Mine G19426 DC PM Pager Motor Assortment

Swiss Moxon Mini DC Gearhead Motor
Electronic Gold
                    Mine G19468 DC PM Gearhead Motor

Mini Cassette Assy
Single motor very much like G18524
Electronic Gold
                    Mine G4586 DC PM Motor Mini Cassette Assembly

Small DC Motor Assortment (3)
1ea: "MH415A"
1ea: "CDX9"
1ea: ?
Electronic Gold
                    Mine G6622 Small DC PM Motor Assortment

Type 3 DC Robot Motor
Electronic Gold
                    Mine G9322 Type 3 Robot DC PM Motor 27.61
Robot Motors (3)
1ea: "Made in China"
1ea: "28002 374941"
1ea:  "MH415A"
Electronic Gold
                    Mine GP21 Rogot DC PM Motors

Below here not Electronic Goldmine

1.5 - 3 Volt Toy Motor


10 each
1.5 - 3 Volt Toy Motor

1.5 - 3
                    Volt Toy Motor
2 Permanent magnets & 3-pole armature
1.5 - 3
                    Volt Toy Motor
(9.92 a. flats)
2x<cass scrw

Silly Happy Crazy Birthday Card Motor

YouTube:  https://youtu.be/ur-xRpW_vmI

5139454 Greeting card with movable parts, Michael L. Earnest, Aug 18, 1992,

Silly Happy
                    Crazy Birthday Card Motor

Maxon A-Max Gearhead
 p/n: 110677 
V 08

Maxon Motor A-max 12mm (104092A)

  • -.75w
  • -3 V
  • -diameter: 12 mm
  • -length: max 20.6 mm
  • -no load speed: 13900 rpm
  • -stall torque: 1.58 mNm
  • -speed/torque gradient: 9010 rpm/mNm
  • -no load current: 21 mA
  • -starting current: 789mA
  • terminal resistance: 3.8 ohm
  • max permissible speed: 12700 rpm
  • max continuous current: 464 mA
  • max continuous torque: .931 mNm
  • max power output at nominal voltage: 565 mW
  • max efficiency: 70.6%

Planetary Gearhead GP13A (110313)

  • -diameter: 13 mm
  • -length: 16 mm
  • -motor shaft length: 11 mm
  • -max motor shaft diameter: 1.5 mm
  • -reduction:  4.1:1
  • -reduction absolute: 57/14
  • -number of stages: 1
  • max continuous torque: .2 Nm
  • intermittently permissible torque at gear output: .3 Nm
  • max efficiency: 91%
  • weight: 11 g
  • avg backlash no load: 1.0
  • mass inertia: .025 gcm2

Maxon A-Max Gearhead 110677, V 08

Fasttech 12.780.02
1.5V DC Micro Motor

Fasttech 12.780.02 1.5V DC Micro Motor
(6.05 across flat)

Fasttech 12.780.00
6V DC Gear Motor
Type: 25GA310-100
DC: 6 V
Speed: 50 RPM/Min
Date: 2012.12.15

Fasttech 12.780.00 6V DC Gear

Floppy Disk Drive
(free defective drive)

Floppy Disk
Bottom spindle motor is center plate
Floppy Disk
Separated major components
Floppy Disk
Spindle Brushless DC Motor (Wiki) assy top
Ribbon cable pin #1 at top, Vcc (#6) at bottom
Floppy Disk

Floppy Disk Drive
Stepper 4-terminal head position motor
Floppy Disk
Parts salvaged from mother board:
Stepper motor
Dual push button switch
Single push button switch
4.0 MHz resonator for microcontroller
47uF 16V cap(meas: 56uF 1.7 Ohm)
200uH inductor
Opto interrupter
Floppy Disk
Inside Spindle Motor 12 Poles (coils)
13 poles on PM in lid?
Floppy Disk

80mm x 80mm Computer Fan
Brushless DC Motor (BLDC)

The fan blade does not want to just
come off like the floppy disk magnet

There are 4 coils and a 4 pin IC marked:  ES211  114009

80mm x 80mm
                    Computer Fan Brushless DC Motor (BLDC)

APM:Rover Components -

1/16 Brushless 4WD Monster Beatle w/ 25Amp System (USA Warehouse)

Hobby King
2040 Brushless Inrunner Motor 4800kv
25A ESC out of stock

1/10 Quanum Skull Crusher 2WD Brushless Monster Truck (RTR)

Other DC Motor web pages:
A.C. Gilbert Erector Set Motor
   Wonder Electric Model Boat Motor
   Z Electric Co. model motor
   Knapp Small DC Motor
Electromagnetic Toy Engine
MESCO 1011 Electric engine
Weeden DC 2-pole Electro-magnetic Machine

Outrunner Brushless DC motor (airplane)

The back plate with 4 tapped holes is stationary,
the silver body and shaft (far end) turn with the propeller.
Note maybe 14 poles?
eBay: A2212 1000Kv Brushless Outrunner Motor For Airplane

Outrunner Brushless DC motor (airplane)

Wireless Power Transfer
5 - 12 VDC Input
5 VDC Output up to 0.5 Amps

eBay:  Wireless Charging Charger Module Power Supply Coil For Cell Phone DIY TX and RX

Wireless Power Transfer 5 - 12 VDC Input 5 VDC
                    Output up to 0.5 Amps

6V GA25Y3/0-46.8   156RPM

from eBay seller leadme-eshop

Gearhead DC PM Motor 6V

6V 25GA370-1.30     30 RPM

from eBay seller leadme-eshop

Gearhead DC PM Motor 6V 25

6V   GB37Y3530-43.8    114 RPM

from eBay seller leadme-eshop

Gearhead DC PM Motor 6V 37

Mabuchi 12V Motor - RS-545SH - Vibrator / Massager / Vacuum Motor - 7130 RPM

Adding a flywheel might make
this into gyroscope.
  • Brand new motor produced by Mabuchi
  • Model: RS-545SH-3045
  • Operates on 5 - 15 VDC (12V Nominal)
  • No load speed: 8,698 RPM
  • No load current: 340 mA
  • Full load (maximum efficiency @ 12VDC) performance characteristics:
    • Speed: 7,130 RPM
    • Current: 1533 mA
    • Torque: 175.3 g-cm (17.18 mN-m)
    • Power output: 11.2 Watts
  • 7.0 A stall current @ 12 V
  • Stall torque 972.9 g-cm (95.35 mN-m)
  • 5 pole armature
  • Can be operated in either direction, simply reverse power supply polarity
  • Dimensions (not including shaft): 50 mm long x 36 mm diameter
  • D-Type shaft dimensions: 16 mm long x 3.2 mm diameter
  • Weight: 5.2 oz. (147 g)
  • Comes with solder eyelets for power connection
  • Two threaded mounting holes on 25 mm centers on drive end
  • These motors are used in hair dryers, vibrators, vacuum cleaners, massagers, etc.

25mm c-c

Mabuchi RS-553SA motor w/ 3.17mm shaft eBay seller:  szbaby11

Voltage: 120 -220 VDC
speed: 10,000 - 20,000 RPM
Shaft 3.17mm dia x 8mm long
M3 mtn screws on 25mm bolt circle
Weight: 177g
shown with one of my flywheels
draws low current at 65 VDC (max voltage of my E3617A bench supply)

Mabuchi RS-553SA motor w/ 2mm shaft

Matsushita VEMS0055
3662240 Small-size direct current motor, 1972-05-09, - 3-pole armature, but only 2 coils.

Pulleys & Gears

FingerTech - S3M Timing Pulley - Timing Belts - 'Viper' R/C Robot Kit (foam wheels for indoor use)

If you know of a source for gears that fit these motor shafts please let me know.
All the suppliers web pages I've seen have a photo but no dimensions for the shaft hole.  They do tell  you the make or model of the vehicle they fit but NO engineering information.

Beams & Construction Supplies

T-Slot beams are handy for making stuff.
Comparison of the starter Kits.

Longest Beam
2#  (includes extras)
2" dia x 3' tube 35-3/8" (898.5mm)
3 # 4 oz
11.5" x 9" x 1" box 11.8" (300mm)

9.5" x 7" x 2" 6" (152mm)

MicorRAX is the lightest weight (strength), OpenBeam is stronger and MakerBeam is strongest of these three (intended for making 3D printers?)


MicroRAX - 10x10mm beam, uses M3 fittings but with special narrow nuts (Starter Kit received 11 July 2013)
The 3 beams that come as part of the starter kit are 35-3/8" (898.5mm) long.
I think the Harbor Freight Mini Cut Off Saw will make cutting the beam easy.
2" dia x 3' tube
2 pounds
MicroRax 10mm
                    x 10mm beam starter kit
Inside tube
MicroRax 10mm
                    x 10mm beam starter kit
Starter Kit + some extras
MicroRax 10mm
                    x 10mm beam starter kit

Right Angle bracket
Uses standard M3 screws & lock washers.
Need 2mm hex bit (not the 1.5mm bit that was also shipped)
MicroRax 10mm
                    x 10mm beam starter kit

Starter Kit (3 beams not shown)  $80
MicroRax 10mm
                    x 10mm beam starter kit

Nut plates instead of standard nuts to fit into the small T-slot.

MicroRax 10mm
                    x 10mm beam starter kit

Extra Parts in addition to the starter kit $40
PCB Standoff Kit
Mounting Bracket for 1/4"
Joining Plate Truss Style
Joining Plate Corner Style
MicroRax 10mm
                    x 10mm beam starter kit


MakerBeam.EU - is a 10 x 10mm beam, uses M3 fittings - from Europe (Starter Kit on order)

When joining two beams to make a right angle corner they fit well.  Haven't checked the angle.
Metal brackets.
You can attach nuts to screws and brackets then slide into beam.
Good variety of brackets.
Using special square headed M3 screws, are they readily available?

11.5" x 9" x 1" box 3 lbs 4 oz
Maker Beam Starter Kit box as received
Contents of Starter Kit
Maker Beam
                    Starter Kit box as received

Corner Joint showing special square headed M3 screw
Maker Beam
                    Starter Kit box as received
End of Beam with screw
Maker Beam
                    Starter Kit box as received


OpenBeamUSA - is a 15x15mm beam, uses M3 fittings - hard to get (Received 11 July 2013) $80
comes with:
2 packages of 8 plastic L Brackets
1 packages of 8 plastic T Brackets
1 bundle of 12 each 6" Beams
A bag of screws
A bag of nuts
A 1mm ball end hex wrench

Uses what appear to be standard M3 hex head screws and nuts.
The corners of the beam are designed to be the rails for a linear motion system.
You can attach nuts to screws and brackets then slide into beam.
Plastic brackets with sloppy holes.
Burs where beam has been cut.

9.5" x 7" x 2"
2 pound box
                    Starter Kit

                    Starter Kit

                    Starter Kit

                    Starter Kit

80 20 Inc - offers 20x20mm T-slot extrusions and larger sizes, also inch sizes
T-Slots - offers 2x2" or 50x50mm and larger extrusions
Parco Inc - 10x10mm - Joining Plates - fractional fasteners -

MiniTec - they have an 11x19mm (1 slot) & 19x19 (2 slots), not the slot on each face like the above products.

MakerSlide - for linear motion (related to Vslot and/or V rail?)

Faztek - useless web pages

Tamiya Pulley Unit Set TAM70121 - (Kit on order)
Tamiya Pulley (L) Set TAM70141 - (Kit on order)
Tamiya Pulley (S) Set TAM70140 -  (Kit on order)


T-Slot Primer - very innovative ways of making connections, much more so than the above.
20, 30 & 40mm beams, but expensive

80/20 Products (YouTube, Playlists)

T-Slotted in sizes: 1", 1.5", 1x2", 20mm, 25mm, 30mm, 40mm, 45mm - many versions including curved to build up a circle.
Quick Frame (hollow square tubing): 1" + square tubing with fins in various places ("P" & "A" tube) plus flanges.
Ready Tube (hollow square tubing w/drilled holes): 1", 1.5" (use with Standard Tube Insert)
a ton of fasteners - Panels  Doors - Floor -Frame - Structrual Shapes - Add-On Components - Finishing Trim - Tools - Kits (EF101 - $254.25) - Basics -

T-Slot "
T-Slot "
T-Slot "
T-Slot 1020




Roller Wheel


Drop-In T-nut


Brake Assy


But Fastener

90 deg Pivot

1/4"  washer


1/4-20 Hex Nut


Lift-Off Hinge

End Caps


Double Slide-in Econ T-Nuts


 Single Slide-In Economy T-Nut

3-hole corner bracket


Panel Mount brackets


2-hole flat plate


2-hole corner bracket

¼-20 x ¾”  FBHSCS
¼-20 x ½”  BHSCS
¼-20 x 3/8”  BHSCS

Anchor Fastener

End Fastener
7/16 Box End Wrench
5/32 Hex Driver
3/16 Hex Driver

Assembly Guide

Storage Case

YouTube: Tech Ingredients: @9:26    80/20 Products -

Electronic Speed Controls (ESC) & Related Controls

Very small DC motors can be controlled using transistors but larger motors run with much higher currents and need high current H bridges.
The input to the ESC is typically the pulse width modulated output from an Remote Control (RC) receiver, but some allow for other input formats like serial bytes or packets.

Dimension Engineering - Sabertooth dual 25A motor driver - Kangaroo X2 Motion Controller -

Pro-Bot -BeeBotLogo language bots

Duratrax - DTXM1200 Electronic Speed Controller (on order 11 July 2013)

G.T.Power RC Servo and ESC Tester (AsiaTees Retail store selling G.T. Power equipment) (on order 11 July 2013)

ESC Tester
Duratrax Sprint 1 ESC w/Reverse opened Top
Duratrax Sprint 1
                    ESC opened Top

Blue 4 MHz resonator at right for PIC, rectangular hole pattern for switch? at lower right

 IRFZ34N HEXFET: 40 milliOhms, 29 Amps (4ea at top, left 2 in parallel, right 2 in parallel)

 IRL3103 HSXFET: 12 milliOhms, 64Amps (4ea at bottom, left 2 in parallel, right 2 in parallel)
Duratrax Sprint 1 ESC w/Reverse opened Bottom
Duratrax Sprint 1
                    ESC w/Reverse opened Bottom
Wire connections at bottom left to right:
Red Batt-,  Blue Motor, White Motor (center big trace), Black Batt-, red/black On/Off sw (BA05 regulator), blk/red/wht servo input

18-pin PIC micro controller
Video of the above setup

The tester has three modes:
1.Manual: turning the knob moves the servo and changes the motor speed from full reverse - stop - full forward.
2.Neutral: the servo is in the center position and the motor is stopped.
3.Sweep: the servo moves back and forth and the motor cycles between full reverse, stop, full forward, stop, etc.

The Electronic Speed Control (ESC) has a 5 VDC output on it's servo cable that powers the tester, so no additional power supply is needed.
That same method probably will power a RC receiver with 5 VDC derived from the 7.2 VDC main battery.
There is also an On/Off switch attached to the ESC which would also power down the receiver.

In the early days of RC instead of the ESC they used a high power wire wound pot driven by a servo.
540-13.5T 3150 Kv Brushless DC Motor & HW 120A Sensored ESC + misc supplies
The black stick with red & black wires is a capacitor too big to fit into the ESC.
540-13.5T 3150 Kv Brushless DC Motor & HW
                    120A Sensored ESC + misc supplies
Dual Motor ESC for Tamiya Bullhead Truck
                    Motor ESC for Tamiya Bullhead Truck


Lynxmotion - Aluminum 4WD1 Rover Kit

Arduino Robot - Maker Shed -

Torssen Robotics - Arms & Legs


Lego has provisions for adding DC PM Motors and this includes shafts, gears, etc.
This was later upgraded to include controllers and sensors.

Before Controllers there were Motors

Long before controllers there were many electric motors.

First Generation 3-C Cell Battery Box & Motors
 (connection cables missing)
Battery box accepts 2 or 3 prong electrical plug.
Lego First
                    Generation 3-C Cell Battery Box & Motors
                    (connection cables missing)

Battery Box may be x468
2-prong electrical plug connects to battery box
and this motor.  8055 motor, different battery box
(the 8055 was a long 3 AA box).
Lego First
                    Generation 3-C Cell Battery Box & Motors
                    (connection cables missing)
Maybe 6216m  motor
These motors have metal strips on bottom and
do NOT accept either 2 or 3 prong plugs.
Lego First
                    Generation 3-C Cell Battery Box & Motors
                    (connection cables missing)
Note 3-hole plug and socket.  4.5 Volt system.

Lego Older DC
                    Motor w/3 prong electrical connector
Note: 2-prong plug and socket, will also fit 3-hole socket.
Older Lego DC
                    Motor with 2 prong electrical connector


This was the first controller and used an 8 bit microcontroller.

First LEGO Brick controller
                    version 1.0 Controller


Official Lego Mindstorms site no longer has RCX stuff

6 AA cells: 9 Volts
                    version 1.0 Controller
IR Tower used as link between computer COM port and the brick
                    version 1.0 Controller
                    version 1.0 Sensor

                    version 1.0 Motor

This might be either 71427 or 43362?
Lego brick with electrical connections,
uses bricks as electrical connection, not prongs.

The black LEGO electrical 2x2 blocks are for
RCX motors. (Wiki)

may be the 2838c01
9 Volt system
Lego First
                    Generation 3-C Cell Battery Box & Motors
                    (connection cables missing)


This is the next upgrade from the RCX controllers.  A more powerful uC and improved motors, sensors, etc.
The LEGO NXT series uses a (non standard) 6P6C modular connector. (Wiki)
The NXT mechanical system is different than the classic Lego bumps.

The NXT motors are called "servo motors" because they contain a sensor.
This is really a "sensored" motor in the parlance of the RC world, whether it be a burshed or brushless motor.

NXT schematics
Deriving power from NXT® motor port A by Philo
NXT "servo Motor" 53787
This is what the RC community would call a brushed sensored gear head motor.
It contains two stages of planetary gears.
                    "servo Motor" 53787
The top and bottom three hole groups are on the standard 8mm
Lego bump pitch.  The "X" hole in the red motor output is
standard Lego.  The four holes on the red motor output are NXT.
Offset notch 6P6C connector
                    "servo Motor" 53787

Power Functions

This is different from NXT.  Power Functions motors are not part of the NXT system.
The GlideWheel PF Motor controller by MindSensors.com allows a NXT controller to operate Power Functions motors.
The Glide Wheel has the mechanical interface so it can be connected to the drive face of a PF motor and it contains the in phase and quadrature rotation sensor needed to make what Lego calls a "servo motor".  That's to say the Glide Wheel when attached to a PF motor makes the motor appear to the NXT system as a "servo motor".  Note:  you can install the Glide Wheel on a motor or after some gearing (but be sure that the direction of rotation is the same).

Power Functions™ presentation by Philo & Didier Enjary

6-AA Battery box, Motors w/attached cables
Gears, couplings, shafts, etc.
9 Volt system
Lego Power
                    Functions 6-AA Battery box, Motors w/attached cables
                    Gears, couplings, shafts, etc.
The motor may be the 58120cx1
Lego 8882 motor
Note: 4 electrical connections (why?) not aligned with brick bumps.

39mm dia x 48mm long
May have 2 stages of planetary gear reduction.
Note:  No classical Lego bumps.
LEGO 8882
                    NXT Motor


This is the next generation due to be released Fall 2013
Mindstorms EV3 (Wiki)

Wheels & Tires

Lego has a standardized axle system that goes all the way back to the first generation motors.  I started looking at Lego because they offer a lot of choices in wheels and tires that can
be used for non Lego vehicles.

LEGO Bulk Lot of Wheels Axles Tires Rims 100 Pieces (on order 11 July 2013)

14mm dia x 9mm wide

NOTE:  These wheel DO NOT accept standard LEGO axles!

Lego Wheels and Tires Large 56 x 28 ZR * NEW
                    Dark Red
Lego Wheels and Tires Large 56 x 28 ZR *
NEW Dark Red (on order 11 July 2013)

Lego Wheels and Tires Large 56 x 28 ZR * NEW
                    Dark Red

Lego Gold Wheels & Balloon Tires 43.2 mm
9441 9444 70502 Ninjago Chima (on order 11 July 2013)

Lego Wheels and Tires Large 56 x 28 ZR * NEW
                    Dark Red

4 Lego NXT Technic Wheels TIRES RIMS 37 x 22 (on order 11 July 2013)

LEGO 24x43 wheel & tire  (Lego size width x radius?)
 24mm wide x 82mm dia

24mm w x 43mm OD
LEGO 24x43 Wheel & Tire

Lego Wheel & Tire (Lego size? 11x21?)
11mm wide x 42mm dia.

7mm w x 17mm OD
LEGO 24x43 Wheel & Tire

Tamiya RC

These are two very old RC vehicles.  They both use a number of common parts.  I think they were sold without the RC transmitter, receiver and servos since they have different brands for these items.  Electronic Speed Controls (ESC) were not available then so a Mechanical Speed Control (MSC) based on a servo was used to move a switch along with a power resistor.  There are three speeds: stop, medium and full.

A problem with the MSC is that the contacts do not always make a good electrical connection and at some throttle positions nothing happens.
Maybe disassembling and cleaning will fix this.

Bullhead Truck 4X4X4 (4 wheel drive - 2 motors & 4 wheel steering)

Tamiya still offers this 1/10 4x4x4 Monster RC Bullhead 58535 & a kit RB889

Two DC motors each 35.5mm dia. Airtronics Tx: AV2R, Rx: 92123 & Servos:.
75.830 MHz.

Tamiya Bullhead
Airtronics Avenger AV2R 2-Channel Remote Control Transmitter
                  Avenger AV2R 2-Channel Remote Control Transmitter
Spectrum Plot from HP 4395A
Airtronics AV2R RC Transmitter Output
Black platform removed holds Mechanical Speed Control
servo and switch deck.  The power resistor is to the right.
Dark blue item is battery.  Servo just to right of battery is
for front and rear steering.
Tamiya Bullhead
The Tamiya TEU-106BK ESC is used in the newer versions of this truck.
It has separate outputs for two motors.  There are other ESCs that also have
dual outputs.

The RC channel 82 receiver (hanging over side above) does not accept today's
 3-wire servo connectors that have the tab.  There are no tabs on these servo
plugs and the wire colors are different.  So the new Dual Motor ESC (below)
does not work.
Rx is loose (rubber bands disentigrated) sitting on top.
Each motor is mounted to a gearbox/differential assembly.
Tamiya Bullhead
Dual Motor ESC for Tamiya Bullhead Truck
                  Motor ESC for Tamiya Bullhead Truck

Tamiya Dune Buggy2 wheel drive 1 motor

"limited release" 49501 Grasshopper II Super G  (93002?)

Same vintage (1992?) as Bullhead Truck above and uses a similar Mechanical Speed Control (MSC) setup with a power resistor.
Why didn't they put a drivers head on  top of the MSC?

Tamiya Dune
Date on back of RC transmitter 1992.
Maybe that's the vintage of these vehicles?

Tamiya Dune
Mechanical Speed Control (MSC) parts removed for ESC
Tamiya 49501
                  Grasshopper II Super G with Duratrax ESC
The MSC has been replaced with a Duratrx Sprint ESC w/reverse
Tamiya 49501
                  Grasshopper II Super G with Duratrax ESC
There's a problem with the ESC not going into set-up mode. 15 Aug 2013.

I received the replacement Sprint II ESC and although it does the correct start up calibration did not run well.
 See: Duratrax Sprint 2 ESC Problem when Starting
The problem was with the new 3500 mAh Ni-MH batteries not strong enough to supply the current needed by the motor.
The original batteries were Ni-Cad and in the 1200 mAh range.
What's needed is a way to test the battery to see how many flash amps it can supply.
See my comparison test of a bunch of 7.2/8.4 Volt batteries for Maximum Available Current

Heli-Max 1SQ Vcam Quad Helicopter

Tower Hobbies carries these.

This is a complete Ready To Fly (RTF) quad copter.  It's very small and light and about $130 for the set.

When flying the Heli-Max it's best to apply full throttle to get the chopper up in the air quickly, rather than trying to slowly raise it up.
If the assent is too slow the chopper tends to move horizontally and soon encounters an obstacle.

A similar product is the Crazyflie Nano Quadcopter except that this kit does not have a regular remote, but instead needs a computer and game controller.  It also does not have an on board camera and uses a lower capacity battery.
The motors and props may be the same? no.

The motors are 7mm dia x 20 mm long and have a shaft dia of 0.93mm.
There appear to be 4 different props, White CW, White CCW, Black CW and Black CCW.
The white props are on the front and the black on the back.  But does it matter where the CW and CCW props go?

Heli-Max 1SQ
                  Vcam Quad Helicopter
The camera (right center) can be manually tilted up or down.
Heli-Max 1SQ
                  Vcam Quad Helicopter
Li-Po battery and USB charger
Heli-Max 1SQ
                  Vcam Quad Helicopter
Note:  left stick down, Mode 2 (half circle at bottom center (press down on right stick to toggle), all four trims are centered, power on prior to connecting battery to Heli-Max.
Heli-Max 1SQ
                  Vcam Quad Helicopter
Pressing Video button controls video camera.
When red LED is flashing it's recording.
Since there's no calendar/clock all the videos will
have a bogus time stamp, but they do have unique
file names.
Heli-Max 1SQ
                  Vcam Quad Helicopter

The Whirlwind Quad Copter is about $70 retail, but does not have a TV camera.

FPV Cameras

There are two types of camera systems.  Recording and First Person Viewpoint (FPV).  Recording systems might use an SD memory card and FPV systems some type of transmitter that can handle video bandwidths.


uThere - Ruby Flight Control & On Screen Display (OSD) - Ready To Fly (RTF) planes w/Ruby -
DIY Drones - APM:Rover Overview

Spektrum - RC radios


This is from eBay July 2019 with title: "LED Solar Powered Lighthouse Statue Rotating Garden Yard Outdoor Lighting Decor" under $15 delivered.  About 10-1/2" tall.
Solar Path light plus rotating reflector.  The motor that drives the rotating reflector seems to be the motor that's used in electric clocks.

First saw this on YouTube BigClive: Really interesting motor inside a solar ornament, 2017-
But this appears to be  an improved version" The roof comes off with a slight CCW wist and has the On-Off switch and battery compartment.  No screwdriver needed to access battery.
A future upgrade would be to add a Fog Horn sound.

Fig 1 taken after putting the AAA battery on charger.
YouTube: https://youtu.be/1ZWdlN-bfzM
The motor does not start when the sun goes down.  The light turns on but the motor does not have enough torque to get the reflector turning.  The LED and wires are not touching the reflector so the problem is with the motor.  See Fig 2 the armature was assembled with only 2 magnets when there are spaces for 4 magnets.  I think that's the problem.  Note I have removed the armature from its normal place and turned it upside down so you can see the magnets.
Fig 1
                      Toy Lighthouse w/rotating lingt
Fig 2 Armature with only 2 of the 4 magnets that are needed.
                      Toy Lighthouse w/rotating lingt

Solar Showcase 360° Turntable

Got this because it uses a clock type DC motor similar to the lighthouse (above).  I'm hoping that I can use this motor in the lighthouse, i.e. that it has more power (magnets).
It does have all 4 magnets and an extra gear so might work in the light house.  The motor body for the turntable is much larger than the lighthouse motor.  Maybe the extra gear and armature can be swapped?
No, when the 4 magnet armature is installed in the lighthouse motor it does not run at all.  . . .  bummer.

Fig 1 Clear plastic turntable.
Solar Showcase
                  360° Turntable
Fig 2 Four solar panels wired in parallel.
Solar Showcase
                  360° Turntable
Fig 3 Note 3 gears for turntable, but only 2 for lighthouse.
Solar Showcase
                  360° Turntable
Fig 4 Individual components instead (?) of an IC.
Solar Showcase
                  360° Turntable
Fig 5 Lighthouse 2-magnet armature on left
Turntable 4-magnet armature on right.
Solar Showcase
                  360° Turntable


Flywheel Pulleys for small DC PM Motors with shaft diameters of: 1.0, 2.0, 3.17, 4.0 & 5.0mm.
Testing DC Motors - YouTube

Gilbert (Erector Set) D.C. Motor -
Wonder Electric Motor 10:1 Gearing
Z Electric Co. 3-pole DC motor
Knapp Small DC Motor
Erector Set - including a very early (unknown) A.C. electric motor
Electro-Magnetic Toy Engine - sounds like a gas or steam engine
Build it YOURSELF!, a REAL ELECTRIC MOTOR - Kit to make a 2 pole D.C. motor & modern version made today & Science First demonstration motor
MESCO 1011 Toy Engine - works like a steam engine
Weeden D.C. Generator -a 2 pole D.C. generator (bought with title DC Motor)
No. 6 Dry Cell - was commonly used to power small permanent magnet DC motors
Self Winding Clock Co. "Western Union" clocks - uses electromagnetic motor to wind spring page 1, page 2 - use 3VDC solenoid and ratchet gear to wind spring

FastTech - low cost DC motors, some geared

The common Drill Press uses T-slots for attaching accessories to the table.

Some 19" Equipment Racks use T-slot technology.


Ref 1.


Turnigy - Brushless DC Motors at HobbyKing - RotoMax 1.20: 1924Watts; RotoMax 1.60: 2960Watts;
Understanding Motor and Gearbox Design - pdf -

UAV-3000 - 3 meter wingspan Predator model

Lego stuff:  http://www.bricklink.com - the eBay for Lego stuff
Michael Gasperi's LEGO Mindstorms NXT/RCX Sensor Input Page
Philo's Home Page

Slot Cars (Wiki) use conventional armatures and pancake armatures. YouTube: Rondo1234560: Pancake Arm Truing & Balancing Pt1 -

PRC68, alphanumeric index to web pages, products for sale

page created in 2013