Need help in designing switching/chopping circuit

j37prakash1

Jul 15, 2011
6
Joined
Jul 15, 2011
Messages
6
I am in need of designing and constructing a switching / chopping circuit to switch a power supply of around 100V dc at the rate of about 250Hz and the Load is a purely Inductive load. The load is nothing but a buzzing coil to switch on and off reed switches at 250Hz frequency. The current through the coil will be around 3A.  It currently runs on an old bulky transformer but the system must be replaced with a solid-state controller. Kindly suggest me if I should deploy SCRs, MOSFETs, or any other device. Please provide me your valuable suggestions and ideas or send me links to any such solutions or references. Thanks a lot in advance for your kind help

 

Hero999

Oct 28, 2007
2,433
Joined
Oct 28, 2007
Messages
2,433
A Reed switch is too slow.

A MOSFET is probably the best solution but the inductor will need to have a supressor diode fitted.

How do you plan to generate the 250Hz signal to drive the MOSFET?

A 555 timer can be used but it needs a lower voltage power supply. You could use the LM317 to generate 12V to power the 555 but it has a maximum input-output differential of 40V so you could use a series resistor in addition to it, to reduce the voltage.

 
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