Resistor question
Resistor question
(OP)
Hello, All:
I would appreciate any help that you may offer.
1) I have an electromagnet application (large inductive load) and in order to ensure a positive release of the work-piece we apply a reversing pulse. (This accelerates the decay of the residual orientation of teh dipoles in the electromagnet's yoke and the work-piece). In our new deisgn we are using a momentary switch (spring loaded) to develop the opposit polarity pulse. The pulse is applied at about 1/4 the normal "on" voltage. Up till now the voltage it has been reduced by a ceramic power resistor.
Does anyone see why a wire wound resitor would not work?
(Fears- Reverse EMF and the wire wound resistor / wire wound resistor acting as an inductor / ?
(I would like to not have to put a reversing diode)
2) Same application, but this is an indicator question. Can I use a 120VAC Neon indicator on rectified AC as though it was on regular AC? (The DC is has only been rectified by a Bridge Rectifier and it has all of the ripple.)
I really appreciate your help.
All the best ,
Mac
I would appreciate any help that you may offer.
1) I have an electromagnet application (large inductive load) and in order to ensure a positive release of the work-piece we apply a reversing pulse. (This accelerates the decay of the residual orientation of teh dipoles in the electromagnet's yoke and the work-piece). In our new deisgn we are using a momentary switch (spring loaded) to develop the opposit polarity pulse. The pulse is applied at about 1/4 the normal "on" voltage. Up till now the voltage it has been reduced by a ceramic power resistor.
Does anyone see why a wire wound resitor would not work?
(Fears- Reverse EMF and the wire wound resistor / wire wound resistor acting as an inductor / ?
(I would like to not have to put a reversing diode)
2) Same application, but this is an indicator question. Can I use a 120VAC Neon indicator on rectified AC as though it was on regular AC? (The DC is has only been rectified by a Bridge Rectifier and it has all of the ripple.)
I really appreciate your help.
All the best ,
Mac





RE: Resistor question
2/ Yes, a neon indicator will operate on DC but you will see that it only glows at one element,
Regards
Roy
RE: Resistor question
In an application like yours, reducing inductive kick-back in DC coils, you can use any resistor you find suitable. Wirewound is very common parallel to excitation windings of all kinds.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Resistor question
This new device is for our mannual power supply and it is very cost sensative. Our PLC driven power supplies do use a step down transformer and a timed pulse for the the reversing. These auotmatic power supplies are performance based and allow for a higher number and higher end components.
Can you make a sugegstion for an indicator which will be wired in parallel to the electromagnet and will operate on the rectified AC. I would like to use as few compoenents as necessary and I have to give an indication that the magnet has power applied. This is in liue of puting an inidcatior on the AC side.
Thanks again!
Mac
RE: Resistor question
Roy
RE: Resistor question