Electric / Electronic Question
 

I have a shop vac.
It has a plug where if I plug in a power tool (sander) it automatically turns on the vac.
The required draw to turn on the vac is 40 watts.
I like to use this vac with pneumatic sanders too. They don't have a plug....

So:
Can I wire a resistor of some sort to emulate an electrical load? I would hook this device to a foot pedal connected to the vac to turn it on without having to put down the tool, switch on the vac, then repeat to shut off the vac. I know this sounds like a first world problem, but in the course of a work day I may start and stop a sanding operation 50 times.
I have rigged up a simple 40 watt lightbulb as said current draw, but that's a little inelegant.

Part 2,
There used to be a model of the same vac that had a pneumatically triggered on-off. This model is NLA. Could I source parts and make such a switch?

Thx!

Is there anywhere to place a foot or knee switch or even a touch switch?

Thinking out loud, but maybe a air switch that completes a circuit when air flows through it. Maybe makes the electrical connection to the wall to vacuum?

clap on-clap off..... ;)

If i understand yoir quest right

Sure you can use a 300 ohm 40 watt power resistor or resistor bank to the same effect as the light bulb. That will give 40w rms load.

Bingo. Thx!


Sent from my iPhone using Tapatalk

That's funny.
Given the same problem, I would have wired up the power supply to the shop vac to the foot switch.

Best
Les

I agree it seems like a wierd thing to do but Im not sure I understand your setup exactly. Wiring a resistor to emulate a load to turn something else on does seem a bit in-elegant


Pressure activated switches for part 2 should be easy enough to find, if not cheap. For example:
https://www.mcmaster.com/#pressure-switches/=1bgbyi5

You must have a current relay that is activated by the current from the device you plug in (i.e. the sander)

The relay closes and the contacts energize the outlet for the shop vac.

Find the contact closure and wire the foot switch in parallel. Then either one will then turn on the shop vac.

For a pneumatic switch perhaps a Hobbs switch would do. Looks like a oil pressure idiot light switch, you can get them with two contacts isolated from the switch body, and an adjustable pressure setting screw.

Search Hobbs Switch. $20-$30