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MAGNABEND HANDYMAN MODEL 

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ELECTRICAL CIRCUIT

Compared with previous Magnabend machines the circuit for the Handyman machine has been redesigned to make it simpler and with lower component cost .
The most significant improvement relates to how the demagnetising is achieved. Previously this was done with a reverse pulse supplied from a pre-charged capacitor.  In the new circuit no pre-charge is necessary, but rather the demagnetising capacitor (C1) recovers sufficient energy from the residual energy that exists in the magnet following turn-off.
This leads to a simpler, but equally effective, circuit and the machine is left automatically demagnetised after each bending cycle.

Broardly the circuit is designed to meet the requirements of the international standard IEC 60204-1 "The Safety of Machinery".

electrical circuit


COMPONENTS:

The components required to build the Handyman circuit have been carefully researched for cost effectiveness. Most of them are available from the global supply companies RS Components or element-14. However sufficient details are provided to enable you to source the components from any supplier of your choice.

The prices, in Australian Dollars, were correct at the time of publishing this web page. Many of the smaller items will be subject to minimum order quantities; for instance the diode must be purchased in a pack of 10. Thus overall cost for the diode will be ($0.54 x 10) = $5.40.

If you source from the suppliers shown below then the total component cost, per Handyman machine, will be around $60.
 
Rocker Switch
Mains ON/OFF switch.
Illuminated rocker, 10 Amp
Panel hole dia 20mm
RS Components
 No. 468 5380
Approx price $5.80


V3 microswitch

V3 Microswitch

SPDT, 16 Amp
Snap-acting.
RS Components
 No. 807 3873
Approx price $5.00
Rectifier
Bridge Rectifier
35 Amp, 1,000 Volt,
Screw mount.
Element-14
 No. 2675368
Approx price $4.25

Cable gland
Cable gland/ clamp,
Hole dia 16mm,
Suits 5~10mm cable
RS Components
No.818 8127
Approx price: $1.10

Start Switch
START button, 22mm.
Momentary pusbutton
10A @ 250V AC
Zhenzhen-1 (eBay)
Approx price: $4.00


demag capacitor

Demagnetising Capacitor,

Electrolytic
1,000uF, 63 Volt,
RS Components
No.711-1637
Approx price: $2.10
relay
Relay, DPDT
230 Volt ac coil,
10 amp
Element-14
No.2811455
Approx price: $6.90


diode

Diode, 1N5404
3 Amp, 400 Volt
RS Components
No. 628 9473
Approx price $0.54
light clamping capacitor
Light Clamping Cap.
6uF, 450 V ac
(Fan motor type)
Designation:
CBB61  SH
eBay price : $9.80
coupling capacitor
AC Coupling Capacitor
100nF, 250V ac
18.5 x 13.7mm x 6.4
RS Components
No. 755-4260
Approx price $1.70

varistor
Metal Oxide Varistor
Clamps at: 650 volts,
Clamping current: 50 amps,
 RS Components
No. 800-7059
Approx price:  $1.00.


bi-metalic2
Bi-Metalic Switch.
SPST, 10 Amps
Open/ Close: 70/55 C
Element-14
No. 1006843
Approx price:  $4.80
Terminal block
Terminal Block
12-way, 12 AWG, 32 A
With wire protectors.
RS Components
No.840-7951
Approx price: $3.50

crimp terminals
Crimp Terminals
Female insulated spade
6.3 / 0.8mm
RS Components
No. 534 351
Approx price $0.28 each
crimp terminals
Crimp Terminals

To suit tabs on the relay.
4.8 / 0.5mm
RS Components
No. 245-5193
Approx price $0.29 each

crimping tool
Crimping Tool
for insulated terminals
Length: 206mm
RS Components
No. 534-812
Approx price: $20.00

Suggested Hook Up Wire:
0.75 mm2, 30m reel, strands: 6/0.25 mm,  RS Components No. 687-7544.  Approx price: $23.00/ reel.


Sheet Metal Layout Drawing for Enclosure: (Click to open the image)

Enclosure drawing

The photo below shows the component layout within the Electrical enclosure.
Click the photo to enlarge it.

Component layout

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This page last updated: 5 January 2021