We have built six simulators to this design in the Durham & Newcastle Association and all have worked well without any attention for several years.
The reason for these comprehensive notes is that the design has evolved towards the easiest and quickest means of construction and also to give guidance to those who may not otherwise consider themselves able to tackle a project such as this.
The sensors are built in small plastic boxes 80 x 60 x 40 mm these are fitted under a frame member adjacent to the outside of the bell wheel. The fixing depends on the type of frame etc. but a wood or plastic bracket and adhesive tape would be adequate
Two small coils are mounted on small pieces of plastic sheet or plywood and secured to the wheel shrouding with a simple clamp.
Four core cable is used to supply power and send the signals from the sensors to the computer (P.C.) running ABEL. The two sensors can be connected together in a daisy chain arrangement to with the single cable clipped under the frame members to give a
The connections to the computer use a simple cable assembly to bring together the signals from the sensors and foot switches and also distribute DC power. This is either taken from the computer drive supply cable as 12 Volts out through an expansion sl
The parts required will cost about £80.00, additionally you will require a redundant 286/386/486 P.C. with a VGA monitor. If you cannot beg one, budget about another £100.00. A sound card is also needed, an ex-office P.C. is not likely to have one fit"
Parts required, all available from Maplin Electronics, Mail order, 01702-554000 or Fax 01702-554001. Also Maplin shops are in most cities.
|Description||Maplin Order Code||Quantity||Component I D|
|Min Resistor 220R||M220R||1||R1|
|Min Resistor 6K8||M6K8||1||R2|
|Min Resistor 1K2||M1K2||1||R3|
|Min Resistor 10K||M10K||1||R4|
|Min Resistor 30K||M30K||1||R5|
|Min Resistor 3K||M3K||1||R6|
|Ver Preset 4K7||UH15R||1||VR1|
|1% Polstyrene 2200||BX60Q||4||C1,C2,CX,CY|
|Disc 0.01uF 50V||BX00A||2||C3,C5|
|Tant 10uF 16V||WW68Y||1||C4|
|100uF 16V Elect.||AT40T||1||C6|
|5 MM RED LED||NP03D||1||LED|
|ABS Box MB1||LH20W||1||Box|
|Description||Maplin Order Code||Quantity|
|Four Core Alarm Cable||PA77J||100 Metres|
|Min Resistor 3K||M3K||2|
|D Range 9 Way Skt||RK61R||1|
|9 Way Hood||KE94C||1|
|Strip Board 3962||JP50E||1|
|4 Pin DIN Plug||HH26D||1|
|4 Pin DIN Line Socket||HH42V||1|
|2.1 mm line Socket||JK11M||1|
|Pin 2145||FL24||1 pack|
|Supply Type||Description||Maplin Order Code||Quantity|
|From Computer||0.2" Power Connector||JW64U||1|
|2.1 mm Line Plug||HH60Q||1|
|47R 3W resistor||W47R||1|
|Spacer M3 insulated||FS37S||2|
|Separate||9 Volt 400mA supply||MG 80B||1|
|M6 x 100 Gutter bolts||4|
|M6 Nyloc Nuts||8|
|M6 Steel Nuts||4|
|Rigid Plastic Sheet, Mains Cable, IEC plugs for Computer, Mains Plugs and Sockets|
Track cuts: where indicated at VR1 and under IC1 and IC2 nine positions.
LED: Fitted on rear side of board on 8 mm lead length. Flat on flange (cathode) towards IC2.
Pin 2145: Fitted in 5 positions, coil, power and output connections."
Mark and drill 4 mm holes on 50 and 20 mm centres in the two pieces of softwood as shown. If possible use a drill stand to ensure the holes are straight.
Fit nails through the holes with the heads projecting 40 mm from the wood and glue in if necessary.
Mark the two pieces of wood to ensure correct alignment and fasten together with the elastic bands.
Push fit the dowel in the reel of enamelled wire to make a handle.
To wind the coils secure the end of the wire under the elastic band and holding the reel in one hand and the blocks of wood on their side in the other. Wind on 30 turns with a hand over hand action, starting and finishing on a short side. The turns sho"
By letting the dowel handle rotate through your fingers an even, light tension can be maintained.
Tie the coil using thread around in eight places secured with a drop of super glue.
Release the elastic bands and the former can be removed from inside the coil.
Pre-tin the lead ends using a hot soldering iron to melt the enamel.
Shorten the coil leads to 15 mm and pre-tin. Solder to the capacitor, take care as this type of capacitor melts!
Fix to the pre-drilled support using hot melt adhesive.
Sleeve with cycle inner tube 28 x 700C size to protect and give a non-slip surface.
Fit M6 gutter bolt with back-nut and washer. Lock nut with super glue.
The two foot switches can be glued onto a piece of wood and labelled. Push out the hinge pins to fit the internal 3K resistors, remove the Co-axial wires and fit a single piece of four-core cable. daisy chained through.
The connector is shown from the front, pin side and the 47 Ohm current limiting resistor can conveniently be mounted together with a cable outlet on an expansion slot blanking plate using insulated stand-offs.
The 9.1V Zener diodes in the sensors will regulate the supply.
The sensors will be affected by metal i.e. frames but this will not be a problem as long as the active area of the coil is at least 150 mm clear.
With the sensors powered adjust VR1 so the activators operate at about twice the normal distance, which should be about 40 mm for reliable operation this can be done before fixing the sensors.
Set-up using the Abel menus and diagnostics.
The clamp design for the activator makes adjustment of striking straightforward
We have not yet needed a faculty for any of our installations, however we always make sure they are temporary. Use clamps and tape, not nails and screws.
Lightning Damage. Your tower would not need to be struck for damage to be possible. Voltages can be induced into the cables by nearby thunderstorms. Get into the habit of disconnecting the sensor connector and unplugging the computer from the mains whe
The PC power supply will only support three sensors. Use a three terminal regulator instead of the 47 Ohm resistor, or a separate PSU.
Each sensor uses about 12mA.
Using unscreened cable between activator and computer has not yet caused any problems with two bells connected. The price difference is the justification.
If this occurs in multiple bell installations reduce R6 to 300 Ohms and fit 2.7K series resistors at the computer end together with 1000 pF capacitors to form a low-pass filter.
The 555 Timer has an output pulse width of 0.33 seconds. This pulses twice in one rotation of the bell. You may have to reduce C4 with light bells to shorten this pulse.
Abel is available mail order on disc (please specify type) from Chris Hughes,
8 Daisy Bank Crescent
CREWE CW3 OHD
Cost £15.00 (All profits to charity or bell restoration)