delay cutoff circuits.... 1

[MichaelWhite]

Hi im designing a circuit that will eventually allow us to control a motor via a switch that when activated will shut the motor down after 5 seconds if the switch is held open and will then stay shut down untill another push button is hit.

so far i have come up with an RC circuit that works well but im having issues with isolating the RC control circuit from the motor contactor becaure of the inductor

I am interested in wether a Solid state relay would work for this or do they have inductance on the control side?

help !

 

[TwnB]

Hi Michael,

I don't know if this will help but I have used an optoisolator in the past to separate the relay coil from the control circuit.

See tutorial on relay drive designs and a little history on relays

http://www.uoguelph.ca/~antoon/gadgets/relays/relays.html

 

[jbartos]

Suggestion: The Solid State Relay (SSR) might be used depending on its design that would include isolation between its input and the output switching part. The schematic diagram of the solid state relay is needed assess the isolation. The timing on the SSR input side must be compatible with the SSR input parameters.

 

[MichaelWhite]

thanks for the info

so a SSR is an optoisolated voltage controlled voltage source with very little input impedance?

if so then thst would be perfect.

 

[jbartos]

Suggestion: Visit

http://www.ciicontrols.com/products/ssdadwg.htm

for SSR schematic. Please, notice that the SSR control voltage may be AC and DC. Each one can accept an RC timing circuit.