MOSFET for inductive load at 110Vdc

[kkdelabaca]

mosfet inductive load

Hello,

I need design one circuit to activate one relay that the coil works at 110Vcd.
I have one previous design with one reed relay that yours contacts activate the coil of the relay at 110Vdc.

In some cases, the reed relay is broken (the contact NormalOpen is internaly cortocircuited). Why protection I can put in this reed relay?

Now, I'm thinking if is posible activate the coil of the 110Vdc with one MOSFET like the IRF820 ( www.datasheetcatalog.org/datasheet/fairchild/IRF820.pdf ). Any sugestion to polarise this transistor?

Thanks!

 

[treitmey]

mosfet with inductive load

I'm not sure if I understand you.
You want to drive a coil with 110 VDC? And use a reed relay to control 110 VDC?
I would think your relay is dead due to "inductive kickback".
When you energize the coil with DC it makes a field.
Then when you open the relay the field collapses. That collapsing field makes
a huge voltage/current. You need a diode to provide that voltage a path to ground.

You will have the same problem with MOSFET.

Use the reed relay with a diode. note: line towards more positive side of coil.

google/Look up "inductive kickback" or free-wheeling diode and driving relays.. because that's what your coil really is.
https://www.allaboutcircuits.com/vol_3/chpt_3/9.html
**broken link removed**

 

[kkdelabaca]

mosfet and inductive load

Thanks treitmey!!

I put one post with more info about the problem and with one posible solution using one bidirectional transil in the "analog section":