I found cheap, simple current sense switches for dust collector

[Jim Becker]

I went a different route which works for me. I use a remote wireless RF transmitter/receiver to control the 220v DC contactor (relay) and put keyfob size remote transmitters at each major tool.

This was my original setup, although a different remote transmitter I suspect...I don't remember at this point what I used. I bought multiple "keychain remotes" and velcroed them near each major machine. When the receiver stopped working, I frankly replaced the remote/transmitter system with one, centrally located toggle switch and just use that for the control side of my contactor. That switch is within a few steps of anywhere in the shop and is 100% reliable.

[John K Jordan]

This was my original setup, although a different remote transmitter I suspect...I don't remember at this point what I used. I bought multiple "keychain remotes" and velcroed them near each major machine. When the receiver stopped working, I frankly replaced the remote/transmitter system with one, centrally located toggle switch and just use that for the control side of my contactor. That switch is within a few steps of anywhere in the shop and is 100% reliable.

I wondered about the life of these things. As insurance, I bought two extra receivers, in part to get more transmitters.

JKJ

[Chris Padilla]

That switch is within a few steps of anywhere in the shop and is 100% reliable.

What about the switchER?

[Mike Heidrick]

Yes - Great note Alan! All of my cheap solutions switch relays and contactors for higher voltage/amperage requirements. ARM work generally has low valtage and highvoltages isolated as much as possible.

I generally try and stick with a 24V or less control setup anyway no matter what I build. No sense running anything higher through the contacts connected to buttons I touch.

[Alan Schaffter]

I don't know if my problem would occur with one of the 'donut' current sensors but I have a mid '90 Fein vac with machine activated plug. I also have a Delta 12" CMS with dual lasers. The lasers are switched but the laser power supply is not. The power supply draws enough current with the lasers turned off that the Fein vac will not turn off. It doesn't turn on without the saw being started but it may or may not turn off. As long as the sensor can be set or if the 'on' amperage is high enough it wouldn't be an issue.

I had a similar problem with the incandescent task lights I mounted to my bandsaw and drill press and the tachometer and VFD I wired to my drill press. The lights were initially wired to receive power through the machine power cords. The trip point of the particular current sensors is too low and would trip when they were turned or left on. In the case of the tach, the initial current surge of the wall wort, not its constant run current, tripped the current sensor. The same goes for the VFD. Even though the drillpress motor was not set to "run," whenever the VFD was powered up the current sensor switch would trip. Once either the tach or the VFD are on (motor not running), the gates will close but since the DC is latched on, I must manually turn it off (the gates re-open and the DC restarts when I select "run" on the VFD), however. In the case of the task lights, I put them on separate 110V power cords (all machines are 220V so current sensors are on those circuits). I never got around to getting current sensors with higher trip points for those two machines.

[Mike Heidrick]

Yes - Great note Alan! All of my cheap solutions switch relays and contactors for higher voltage/amperage requirements. ARM work generally has low valtage and highvoltages isolated as much as possible.

I generally try and stick with a 24V or less control setup anyway no matter what I build. No sense running anything higher through the contacts connected to buttons I touch.

[Mike Heidrick]

Most VFDs have intelligent relays and can perform any switching and time delay switching you could ever want. I use a VFD setup to keep my CNC's water cooling pump moving coolant through my spindle and keep it on on for 15 seconds after the motor stops between jobs in case I start a second job or restart the same job.

[Curt Harms]

This was my original setup, although a different remote transmitter I suspect...I don't remember at this point what I used. I bought multiple "keychain remotes" and velcroed them near each major machine. When the receiver stopped working, I frankly replaced the remote/transmitter system with one, centrally located toggle switch and just use that for the control side of my contactor. That switch is within a few steps of anywhere in the shop and is 100% reliable.

That's what I did. My shop space isn't that big and machines are on mobile bases and are used in pretty much the same spot. Light switch screwed to the side of the overhead air cleaner connected to the control connections of a contactor. Never gets lost and seeing as the switch is switching < 1 amp I expect it'll last quite a while. If I had a larger space I'd probably go with low voltage control and several start/stop stations.

[Jim Becker]

What about the switchER?

It's true that the "switchER" has occasional issues, but that's more about biological aging...

[Jim Becker]

That's what I did. My shop space isn't that big and machines are on mobile bases and are used in pretty much the same spot. Light switch screwed to the side of the overhead air cleaner connected to the control connections of a contactor. Never gets lost and seeing as the switch is switching < 1 amp I expect it'll last quite a while. If I had a larger space I'd probably go with low voltage control and several start/stop stations.

My switch is on the underside of the stairs that are over my slider...pretty much in the middle of the shop, but skewed toward where most of the operations are done. My shop is ~ 22' x 30', so it's still only mere steps from "anywhere" and I'm not prone to turning the DC off after every little cut anyway. The cyclone is in a sound insulated closet so leaving it run a little doesn't really affect things as I go about my tasks.

You visited my shop awhile back, didn't you?

[Lynn Kasdorf]

Do an ebay search on sct-013-000 non-invasive AC Current Sensor Split core Current transformer. They are about $5 delivered. They can also easily be placed around wires you already have run with plugs on them. There are other models there for $5-$6 as well.

These look pretty good, especially for the price. I've not found any documentation on what the connections are though. Do they give you contact closure when current flows, or a signal or open collector or what?

[Alan Schaffter]

These look pretty good, especially for the price. I've not found any documentation on what the connections are though. Do they give you contact closure when current flows, or a signal or open collector or what?

That unit is NOT a switch. It is a current sensing transformer- when current flows through the monitored wire, it creates a small current in the the coil. The leads connect to the coil. The current can be used with the appropriate circuit to monitor and/or control electric stuff.

Here are two links- one to an article about using the sensor with an Arduino and the second (from the first link) to an explanation how the sensor works:

http://www.homautomation.org/2013/09...r-and-arduino/

http://openenergymonitor.org/emon/bu...nt-transformer