build a magnetizer/demagnetizer

I'm following Birk Peterson's published plans (Machinist's Workshop
April/May 2003) to build a magnetizer/demagnetizer using the
coil from a surplus solenoid. On first pass it worked real well but after
two or three 2 second cycles it burned up the coil. The coil came from a
big Dormeyer intermittent duty relay. If I use a coil from a continuous duty
relay will it survive longer?
Any advice?
It's a 115 Vdc circuit with a bridge rectifier to energize dc to mag and A/C
to demag.
Thanks in advance.
Rick
Reply to
Rick Legge
Loading thread data ...
hx?U?AÓ0?ïùs¢ A»Zn°ZâRÁj qvíI2ÔñXãq£ì¯g?VËö?¦ã7ß{ÏùIþßqfaÅÝ?ô#ì7ô#?øBr?¨(??@®?HeÄ9ºTàõ?ó#%*jþa9??ó?î?õ>g¡¸{p ÜÞ?Êp¨8??Pé eðÿ¨¥­Ö¯?üE¯&Ó9 ºf?-¥@¥Pvj²???±t³A?íº_#?÷? 4°´?0?¥Ñ­ay ??ÒÙr*?3|C
Reply to
Jim Stewart
Magnetising ?
Doh ! No wonder it failed. Try to find a design from someone who has something resembling a clue.
You don't need a constant field to make a magnetiser, you need a unidirectional field. So long as it retains the same polarity, a pulsed field is OK.
A solenoid winding (relay, transformer or motor) is a reactive load, which means that it has a higher impedance at AC than at DC. For AC, even at 50Hz, this impedance limits the current. Run it on DC though and it's the same as sticking a fairly short length of copper wire straight across the supply - no wonder it burned out !
Most decent magnetisers are pulsed, using a capacitor bank. Real ones also monitor the winding temperature, or else limit the duty cycle.
-- Smert' spamionam
Reply to
Andy Dingley
I built a demagnetizer by making a coil of some (16ga?) magnet wire that I had laying around. Its resistance is way too low to connect to 110 directly, so I connect it in series with a high-wattage device. E.g., a blow dryer. Works fine. Bob
Reply to
Bob Engelhardt

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.