Thrift,

Great little circuit, and thanks for the links.

I can't believe how highly reviewed that contactor is, considering the price! Great resource, thanks for the ideas

 

Kingspoint? I know what that is.

MSC?

 

nope, work for an oil major for the past 24 or so years.

 

I built a heavy duty high current remote switch using a cheap remote for Christmas lights and a heavy contactor. It can handle a 60 amp load. Did tis for about $30.00.

 

Use the Christmas light control to energize the contactor coil and you've got it. Just buy the Christmas light control at the end of season when they're clearing the shelves of holiday stuff. They're really cheap at that time.

 

Thank you very much for putting a pdf and links for us together.

True altruism.

I will be building this ASAP.

None of the ones on the market I have seen handle over 12 or 14 amps.

 

I had the same problem finding a solution and enjoyed making something that worked.

 

I found that the simplest, cheapest way was to use one of these master/slave modules, nothing else required and the cost was about $20.00. For the two saws I, with the help of a friend built two programmable units whereby the DC comes on after the saw has reached full speed and off after a delay to collect any remaining dust.

 

I found that the simplest, cheapest way was to use one of these master/slave modules, nothing else required and the cost was about $20.00.

The Kemo units don't appear to be available in 120VAC America. Various low amperage switches are available to us, such as these

Current Sensing Relay (AS1 Series) | NK Technologes - San Jose, CA 95136

but the prices are in the $50 to 80 range. So, it's a current switch and contactor for us.

 

I thought that Ebay USA would have the 120 volt versions. As a matter of interest I thought that many shops in America had 120/240 volts available.

 

Harry,

Most of the tools sold are 110v. Larger bandsaws, table saws, and dust collectors are 220v. For the most part, if it would draw less than 15 amps, it probably is 110v.

 

Thrifty, what is the current draw of the contactor coil? I couldn't find a datasheet or other info. I did see some info on one of the units it "replaces" that seemed to indicate several amps at 110VAC. The CR9321-ACA looks to be spec'd to .8 A. Since your circuit doesn't throw flaming balls of fire, I have to assume that the contactor coil pulls lower current. I would think an AC coil would be well less than 90 Watts but am a bit surprised the info is so hard to find.

Also, have you thought about adding a snubber circuit? It might be a good idea to reduce arcing across the contactor's contacts. Though, given they are so cheap, a shorter life isn't much of a hardship.

 

1) Someone on a homebrewing website measured the coil holding current as 50 mA.

2) I contacted CR Magnetics about a "Snubber Circuit" and sent them a drawing of the circuit. They said I was good to go without a snubber. That was very good news, since I have no clue how to build a "snubber circuit"

BTW, during this process, I also found that higher quality NK Technology current switches can be found on Ebay for $25~30. While I have no doubt they'll last longer, they are larger the CR Magnetics product. In addition, some of the more expensive NK current switches include on-off delay and a variable switching current level.

 

Thanks. That's helpful. Usually holding current is about 1/4 the make current so it should be well within the spec of the cr magnetics component.

 

Well, I must report that my original selection of the Cr Magnetics current switch has been a disappointment. The switch worked 10-times then failed to function properly. I contacted the supplier and they were quite helpful up to the point at which it was obvious that the switch wasn't functioning. At this point, they stopped responding to my emails.

So,while the circuit is good, I would suggest looking a higher quality current switch, such as the NK Technologies units.

 

Thanks for the update.

 

Well I'm glad I seen this thread , as I was going to install a switch in my wall for my DC , but I never knew there was an option for monitering current draw . I like that much better because I always forget to turn it on

 

One of these fixed or split core units will work

NK Technologies AS1 Nou FF AC Current Switch Universal Output 1 150A Input Range | eBay

Ebay is the best source. Check for free shipping and sellers willing to accept best offers.

Here is the company catalog site for the AS1 units

AS1 Current Sensing Relay | NK Technologies

 

So its been two years, how are these home made versions working out after this long?

 

I have a couple of Christmas light remotes and plan to use them to trigger the DC using that remote. I move my DC hose from tool to tool, so the remote is a better choice and I have two collectors, on in each shop area I'll do this with. I found the remotes had 6 different channels, so I got one of each. Nice to have a couple so I don't have to go outside on cold December nights. Thanks fo rthe wiring diagram.

 

Check the Amp draw on the remotes vs the DC. I've been using one with my shop vac and it works. Yesterday I tried it with the new Hazard Fraught dust collector but it drawes too many amps (may have toasted the switch).

 

I'm almost done building a shed on the outside if my garage to hold the dust collector and air compressor. I ran new wires, adding new breakers to outlets in the shed, with switches to cut power. So my power supply to the DC is easily accessible to install some remote.
All my tools run off a single circuit, ok since I don't use them simultaneously. So it would be pretty easy to install either a remote or an auto switch. As soon as I can find the right one.

 

http://www.routerforums.com/kp91s-g...s.com/kp91s-gallery/97769-why-spend-60-when-you-can-build-30-a.html#post1254361

Everend,

This one still holds up well, I am going to change the cord to a longer one, but that is about it. The contractors are really cheap online