Electrical Circuit

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MAGNABEND HANDYMAN MODEL

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".

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.


Mains ON/OFF switch. Illuminated rocker, 10 Amp Panel hole dia 20mm RS Components No. 468 5380 Approx price $5.80	V3 Microswitch SPDT, 16 Amp Snap-acting. RS Components No. 807 3873 Approx price $5.00	Bridge Rectifier 35 Amp, 1,000 Volt, Screw mount. Element-14 No. 2675368 Approx price $4.25	Cable gland/ clamp, Hole dia 16mm, Suits 5~10mm cable RS Components No.818 8127 Approx price: $1.10
START button, 22mm. Momentary pusbutton 10A @ 250V AC Zhenzhen-1 (eBay) Approx price: $4.00	Demagnetising Capacitor, Electrolytic 1,000uF, 63 Volt, RS Components No.711-1637 Approx price: $2.10	Relay, DPDT 230 Volt ac coil, 10 amp Element-14 No.2811455 Approx price: $6.90	Diode, 1N5404 3 Amp, 400 Volt RS Components No. 628 9473 Approx price $0.54
Light Clamping Cap. 6uF, 450 V ac (Fan motor type) Designation: CBB61 SH eBay price : $9.80	AC Coupling Capacitor 100nF, 250V ac 18.5 x 13.7mm x 6.4 RS Components No. 755-4260 Approx price $1.70	Metal Oxide Varistor Clamps at: 650 volts, Clamping current: 50 amps, RS Components No. 800-7059 Approx price: $1.00.	Bi-Metalic Switch. SPST, 10 Amps Open/ Close: 70/55 C Element-14 No. 1006843 Approx price: $4.80
Terminal Block 12-way, 12 AWG, 32 A With wire protectors. RS Components No.840-7951 Approx price: $3.50	Crimp Terminals Female insulated spade 6.3 / 0.8mm RS Components No. 534 351 Approx price $0.28 each	Crimp Terminals To suit tabs on the relay. 4.8 / 0.5mm RS Components No. 245-5193 Approx price $0.29 each	Crimping Tool for insulated terminals Length: 206mm RS Components No. 534-812 Approx price: $20.00