Frequency Limit Relay

[Brandnew]

Hi,

I'm trying to find a relay that will open (or close) after a certain frequency is achieved. Ideally the relay would be adjustable to allow for fine tuning but this is not necessary. I'm looking to find a relay like this or I will build my own if need be!!

I have a signal from a VSS that is 0-4.5V (DC). The frequency from this switch comes in a squarewave and varies with speed. When the frequency gets above 30Hz I want the relay to open.

Any ideas where to find a relay like this?? Thanks!!

 

[carnage]

your concept can be done without to much trouble, but what you need to look into is a control for the relay, to the best of my knowledge no relay will do this on its own.
I would suggest off of the top of my head a frequency to voltage converter, hooked to a simple comparater circuit who's output drives the relay.
this would require in total
2ic's (1 op amp, 1 freq to vltge conv)
1 normaly closed relay
and a few resistors to set the voltages.

make sure that the op amp is capable of sourcing the current required to operate the relay you select.

hope this helps.
p.s. there is most likely a device that would make a simpler circuit than this, but I know this one will work.