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Horizontal Electric Engine
By Gilbert Ghyselbrecht
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Control your Meccano models (or anything else) from your Windows PC!
Take a look at my new MECControl project at meccontrol.com

Using the principles of a horizontal steam engine I constructed a model in which the steam cylinder is replaced by an electromagnet with a moving core.  The construction details of the model are of little importance, as the photos give all the information you need.

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Front of model
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Back of model
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How the Cylinder Works

The cylinder is replaced by an coil, while an iron core replaces the piston of a steam engine.  The construction details of both are shown in the photos below.

If the core is placed about half of its length into the coil, and the current is then switched on, the core will be sucked right into the coil.  The current will then be automatically switched off by the associated electronics.  The core keeps on moving, due to the energy stored in the flywheel, until it comes out at the other end of the coil.  When the current is then switched on again the action repeats in the opposite direction.  The core (piston) is pulled alternately backwards and forward thus forming a reciprocating engine.

Plastic tube (5/8" length) with an epoxy or bakelite flange at each end

Plastic tube (5/8" diameter) with an epoxy or bakelite flange at each end

Coil mounting brackets. Must be made of aluminium or copper (non magnetic)

Coil mounting brackets. Must be made of aluminium or copper (non magnetic)

The empty coil in its brackets

The empty coil in its brackets

Wind 9 layers of insulated copper wire (0.75mm diameter) onto the tube

Wind 9 layers of insulated copper wire (0.75mm diameter) onto the tube

The coil must fit in a Meccano cylinder (part 216)

The coil must fit in a Meccano cylinder (part 216)

The iron core (57mm length, 12mm diameter) and bronze axle rod (4mm diameter)

The iron core (57mm length, 12mm diameter) and bronze axle rod (4mm diameter)

Figure 1: Details of the soft iron core

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The completed cylinder and core in the model
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Controlling and Regulating the Cylinder

Two slotted opto switches are used to control the electromagnet and regulate its speed, placed as shown in the photos below.  The slotted opto switches are mounted on the same printed circuit boards (PCBs) that I used in my Cliff Lift model.  The only difference is that one third of each has been cut off due to the proximity of the slotted opto switches to the gearwheel in this model.

Further Information A Cliff Lift - Includes a description of slotted opto switches and a photo of the PCB mentioned above

The first slotted opto switch switches the electromagnet current on and off using two shutters mounted on a gearwheel (Meccano part 95b) coupled to the flywheel.

The second slotted opto switch measures the speed of the engine using the teeth of the same gearwheel.  This speed information controls the current through the coil and acts as a regulator.

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The gearwheel and slotted opto switches
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The on/off slotted opto switch and shutters (right)
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The speed slotted opto switch
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The Circuit

Figure 2 shows the block diagram of the system, and figure 3 shows the full circuit diagram.  The circuit diagram can also be downloaded separately from the link below.

Downloads Full Circuit Diagram - GIF image format (86kb)

Figure 2: Block diagram of the system

IC1 is a 555 timer and it is configured as an astable.  Using the Reset input (pin 4), the Output (pin 3)  is switched on and off under the command of the On/Off slotted opto switch sensor. The square wave signal at the output of the 555 drives a power MOSFET transistor BUZ11.

A second 555 timer, IC2, is configured as a monostable.  It is triggered by the Speed slotted opto switch sensor and transistor T1.  The output pulses are integrated to form a DC component used as control voltage for IC1 (input into pin 5).  The control voltage has the effect of changing the frequency and the duty cycle of the square wave signal output from pin 3.  The current through the coil will therefore vary from 0.5A to 4A and so the engine will run at a constant speed.  The speed can be set using a potentiometer to change the monostable time period of IC2.

Further Information The 555 Astable Circuit
The 555 Monostable Circuit

Figure 3: Full circuit diagram (Click to enlarge)

Figure 3: The full circuit diagram (Click to enlarge)

Building the Circuit

If you have the facilities to produce printed circuit boards, you can build the circuit using the PCB design which is available to download in GIF format below.  To make printing the design at actual size easier, it is also available in a Microsoft Publisher file which can also be downloaded from the links below.  This file also includes the component layout diagram which is also shown in figure 4.

Downloads PCB Design - GIF image format (42kb)
PCB Design and Component Layout - Microsoft Publisher 2000 format - zipped (132kb)
PCB Design and Component Layout - Microsoft Publisher 2000 format - uncompressed (540kb)

The size of the PCB should be 3.5" x 2.5".  The 14 mounting holes in the PCB should be drilled using a 4mm bit so that they accept Meccano bolts.

Figure 4: PCB component layout

Further Model Details

The photos below are close-ups of the speed setting potentiometer and mechanism, piston, and circuit.

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The speed setting handle
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One end of the cylinder
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Speed setting potentiometer and associated gearing
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The position of the circuit in the model
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The PCB
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 Shopping List

Here is a list of parts required to build the circuit in figure 3 on the PCB given in figure 4. It includes a reel of insulated wire for the coil. The BUZ11 transistor is unavailable from Rapid.

Part
Description
  Quantity
Required
  Rapid
Code
  Unit
Price
  Total
Price
0.01μF Metallised Polyester Film Capacitor   1   64-2381   0.26   0.26
0.1μF Metallised Polyester Film Capacitor   1   64-2384   0.26   0.26
0.1μF Tantalum Bead Capacitor   2   11-1056   0.15   0.30
0.22μF Metallised Polyester Film Capacitor   1   64-2386   0.30   0.30
10μF 63V Radial Electrolytic Capacitor   1   11-0225   0.05   0.05
100μF 35V Axial Electrolytic Capacitor   1   11-0060   0.32   0.32
100kΩ 0.4W Miniature Linear Potentiometer   1   65-0730   0.56   0.56
10kΩ 0.25W Metal Film Resistor   2   62-3474   1.40
(per pack of 100)
  1.40
15kΩ 0.25W Metal Film Resistor   1   62-3478   1.40
(per pack of 100)
  1.40
180kΩ 0.25W Metal Film Resistor   1   62-3504   1.40
(per pack of 100)
  1.40
1kΩ 0.25W Metal Film Resistor   1   62-3450   1.40
(per pack of 100)
  1.40
1N4007 Rectifier Diode   2   47-3142   0.05   0.10
220Ω 0.25W Metal Film Resistor   1   62-3434   1.40
(per pack of 100)
  1.40
2-way PCB Mounting Terminal Block   2   21-0471   0.16   0.32
33kΩ 0.25W Metal Film Resistor   3   62-3486   1.40
(per pack of 100)
  1.40
38mm Heatsink for TO220 Style Transistor Cases   1   36-0226   1.02   1.02
3-way PCB Mounting Terminal Block   2   21-0473   0.20   0.40
470Ω 0.25W Metal Film Resistor   1   62-3442   1.40
(per pack of 100)
  1.40
500g Reel of 0.71mm Diameter Enamelled Copper Wire   1   -   0.00   0.00
5mm Standard Red LED   1   55-0155   0.09   0.09
7808 1A Regulator   1   47-3600   0.58   0.58
8-pin Dual-in-line IC Socket   2   22-1720   0.23   0.46
BC547C Low Power NPN Transistor   2   50-3115   0.02   0.04
BUZ11A MOS-FET Transistor   1   -   0.00   0.00
NE555N Timer IC (Standard 555)   2   82-0336   0.23   0.46
Slotted Optoswitch   2   58-0303   1.70   3.40
Grand Total   18.72

Full printer-friendly parts list

Order the above items from Rapid Electronics via our Circuits Shop and help support the Electronics in Meccano website, without affecting the price you pay! Just click on an item for information about it and/or to add it to your Rapid order.

Orders can also be placed by telephoning Rapid on 01206 751 166 or visiting their website at www.rapidonline.com. Prices quoted include VAT at 20%.

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Article Information
Topic: Model Studies | Created: 03/01/2003 | Last modified: 11/02/2007

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