Help with Circuit Design

At it's crudest level...

2 relays, a diode, resistor and a capacitor..

D from BC

Just go here:

and search for H3DE timer. It does exactly what you want.

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John B

Your table saw switch already does exactly what you want it to do for the table saw. For the shop vac, all you need to do is connect a timer relay as mentioned in the other posts to the "output" of your table saw switch.

Chuck

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You only need one relay - for the vac. Also, you will need a rectifier and transistor to drive the relay.

Tam

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Why not just use a normal relay (or just a switch) for the table saw
and an off-delay relay for the shop-vac?  

Basic Stamp.

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Many thanks,

Don Lancaster                          voice phone: (928)428-4073

Sears sells a plug in box that does just that. Of course you could roll your own. I would start by detecting the current in the table saw circuit, then have a relay close energizing a second feed to the shop vac. I know my shop vac is something like 13A, and my saw is probably close to 15A therefore I suggest using two separate feeds.

Search for a delay off timer.

On Sat, 20 Jan 2007 10:28:32 -0700 in sci.electronics.design, Don Lancaster wrote,

Hah! A 555 would be cheaper.

Go to this link

and look for "Power Off Time Delay Relay Circuit" near the bottom

I second that but use 1 solid state relay, 1 diode , 2 resistors (voltage divider) and 1 capacitor..... bobs your uncle.

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Thanks for the suggesti>