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.
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 ListL1 Shape: Flat (F), Round (R), Square (S)
Decoding Mabuchi part numbers: L1L2-N1N2N3L3L4-N4N5TTTT
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.
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.
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 =
The motor resistance is about 2.5 Ohms including the wires from the power supply.
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.
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.
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.
Maxon A-max26mm 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 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 permenant magnet DC carbon brush motor & DT2234A+ digital Optical tachometer
Aluminum foil and painters blue tape wrapped around gear for tachometer.
Two 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).
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?
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
Bertsch Micro Motor
RF-520C-17410 Efficient DC Motor
Enclosed 12VDC Motor
G17687 2 Motor Drive CD Head Assy
Spindle: BCD3B, 05UD8X31A
24.0 DIA X 11.0
SHFT: 1.96 DIA x 7.7
Head traverse: BDH3B, 06.8x22a
25.84 DIA X 9.91
Spindle & Head Assembly motors
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.
Mirrors in Optical Assembly
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.
Our Best DC Motor Assortment
1 ea: "RF-520C-17410" G16280
1 ea: "CDX9" G?
1ea: "30011 Johnson 371421"
Very Efficient Pancake Motor w/Pulley
Massive 12VDC Motor
Heavy Duty DC Motor
Micor Pancake Vibrator Motor
Might be brushelss, Allegro A1442 - AN205049
Microchip TD6505 is a 3-phase fan controller with PWM input.
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
Pager Motor Assortment (3)
Swiss Moxon Mini DC Gearhead Motor
Mini Cassette Assy
Single motor very much like G18524
Small DC Motor Assortment (3)
Type 3 DC Robot Motor
Robot Motors (3)
1ea: "Made in China"
1ea: "28002 374941"
Below here not Electronic Goldmine
2 Permanent magnets & 3-pole armature
(9.92 a. flats)
Maxon A-Max Gearhead
Maxon Motor A-max 12mm (104092A)
- -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
1.5V DC Micro Motor
(6.05 across flat)
6V DC Gear Motor
DC: 6 V
Speed: 50 RPM/Min
Floppy Disk Drive
(free defective drive)
Bottom spindle motor is center plate
Separated major components
Spindle Brushless DC Motor (Wiki) assy top
Ribbon cable pin #1 at top, Vcc (#6) at bottom
Stepper 4-terminal head position motor
Parts salvaged from mother board:
Dual push button switch
Single push button switch
4.0 MHz resonator for microcontroller
47uF 16V cap(meas: 56uF 1.7 Ohm)
Inside Spindle Motor 12 Poles (coils)
13 poles on PM in lid?
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
APM:Rover Components -
1/16 Brushless 4WD Monster Beatle w/ 25Amp System (USA Warehouse)
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
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
6V GA25Y3/0-46.8 156RPM
from eBay seller leadme-eshop
6V 25GA370-1.30 30 RPM
from eBay seller leadme-eshop
6V GB37Y3530-43.8 114 RPM
from eBay seller leadme-eshop
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.
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
shown with one of my flywheels
draws low current at 65 VDC (max voltage of my E3617A bench supply)
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.
T-Slot beams are handy for making stuff.
Comparison of the starter Kits.
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
Starter Kit + some extras
Right Angle bracket
Uses standard M3 screws & lock washers.
Need 2mm hex bit (not the 1.5mm bit that was also shipped)
Starter Kit (3 beams not shown) $80
Nut plates instead of standard nuts to fit into the small T-slot.
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
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.
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
Contents of Starter Kit
Corner Joint showing special square headed M3 screw
End of Beam with screw
OpenBeamUSA - is a 15x15mm beam, uses M3 fittings - hard to get (Received 11 July 2013) $80
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
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
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 -
90 deg Pivot
1/4-20 Hex Nut
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
7/16 Box End Wrench
5/32 Hex Driver
3/16 Hex Driver
YouTube: Tech Ingredients: @9:26 80/20 Products -
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 -BeeBot - Logo 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)
Duratrax Sprint 1 ESC w/Reverse 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
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 potent 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.
Dual Motor ESC for Tamiya Bullhead Truck
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.
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).
Maybe 6216m motor
These motors have metal strips on bottom and
do NOT accept either 2 or 3 prong plugs.
Note 3-hole plug and socket. 4.5 Volt system.
Note: 2-prong plug and socket, will also fit 3-hole socket.
This was the first controller and used an 8 bit microcontroller.
First LEGO Brick controller
Official Lego Mindstorms site no longer has RCX stuff
6 AA cells: 9 Volts
IR Tower used as link between computer COM port and the brick
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
NXTThis 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.
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.
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
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
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.
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 (on order 11 July 2013)
Lego Gold Wheels & Balloon Tires 43.2 mm
9441 9444 70502 Ninjago Chima (on order 11 July 2013)
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 Wheel & Tire (Lego size? 11x21?)
11mm wide x 42mm dia.
7mm w x 17mm OD
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:.
Airtronics Avenger AV2R 2-Channel Remote Control Transmitter
Spectrum Plot from HP 4395A
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.
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
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.
Dual 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?
Date on back of RC transmitter 1992.
Maybe that's the vintage of these vehicles?
Mechanical Speed Control (MSC) parts removed for ESC
The MSC has been replaced with a Duratrx Sprint ESC w/reverse
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?
The camera (right center) can be manually tilted up or down.
Li-Po battery and USB charger
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.
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
The Whirlwind Quad Copter is about $70 retail, but does not have a TV camera.
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
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.
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 2 Armature with only 2 of the 4 magnets that are needed.
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.
Fig 2 Four solar panels wired in parallel.
Fig 3 Note 3 gears for turntable, but only 2 for lighthouse.
Fig 4 Individual components instead (?) of an IC.
Fig 5 Lighthouse 2-magnet armature on left
Turntable 4-magnet armature on right.
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 GearingErector Set - including a very early (unknown) A.C. electric motor
Z Electric Co. 3-pole DC motor
Knapp Small DC 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.
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