I need to turn ON (and OFF if possible) a vacuum when another DIY tool, like a drill, is activated/deactivated.

The idea is: "I start working and the vacuum start sucking dust automatically. Then it stop when I stop working".

The tech spec. are (both for tools and vacuum):

  • Voltage: 230V
  • Current (max): 16A

NOTE: I don't want another manual switch to turn on both. I want an automatic system which detect when the load (the tool in this case) is turned ON and turn on a "slave" switch (like via relay) to power on the vacuum.

  • 3
    \$\begingroup\$ Just buy a master slave power strip? \$\endgroup\$ – PlasmaHH Sep 11 '17 at 9:33
  • \$\begingroup\$ The problem this idea has is the vacuum cleaner needs a while to start. It starts sucking as soon you are done with drilling. \$\endgroup\$ – Janka Sep 11 '17 at 12:19
  • \$\begingroup\$ @Janka You forgot that the drill also takes a while to begin spinning in a nice speed, so both take approx. the same amount of time. \$\endgroup\$ – Fusseldieb Sep 11 '17 at 16:02
  • \$\begingroup\$ I think the OP is talking about a portable drilling machine as it was no problem to equip a no-portable drill with a double-throw switch. Portable drills typically need less than 500ms to reach their idle speed. A vacuum typically needs more than 2s. \$\endgroup\$ – Janka Sep 11 '17 at 16:52
  • \$\begingroup\$ @Janka Given the time for aligning the piece and begin cutting properly, 2 or more seconds have probably passed already. And even if not, there isn't a machine to predict if you'll cut something and turn on 2 seconds before. The OP could use 2 relais, a Arduino and a switch. When he turns the switch, a GPIO of the Arduino will be closed, making the first Relais turning on (where the vacuum is) and then after 1.5s the other Relais (where the tool is) turning on. The only downside is the delay, but there is really no other way, as I said. \$\endgroup\$ – Fusseldieb Sep 11 '17 at 18:41

You could buy an non-invasive current sensor, a 5V 10A relay or two relays switched on together to drive 20A and an Arduino Pro Micro.

With that "setup" you can easily hook up the relay and the current sensor to the Arduino and program it to turn the relay on, if more than xx current is flowing through the sensor.

Because the sensor is non-invasive, it means you can put it on the tools power cord without cutting the AC wires (or doing other dangerous things) and it'll work just fine.

How you can read the sensor with the Arduino you can read here and turning the relay on is as easy as writing two lines of code (setup pin xx, set pin xx).

It'll cost you less than $20 (if you pick an Arduino clone), and it will work for ages, as the Arduino has practically no parts that can fail over time.

I made a image showing how it will be connected:

Setup v2 (To measure the current correctly, you should pass only one wire of the power cord to the non-invasive current sensor, not both. If you don't care about it and just put the entire cable through, it won't measure the current properly, as the energy is flowing in a loop, resulting in [near] zero.)

The Arduino Pro Micro needs a very very very tiny amount of energy (approx. ~10 mA), this means any super-cheap micro-USB wall adapter will work just fine. There are even instructions to solder out some components and including a library in it so that it doesn't consume more than some uA!

EDIT: Oh, and as you may have guessed, you can plug it into any USB power source to power it (PC/Notebook/Wall Adapter/Toaster?/...).

| improve this answer | |
  • \$\begingroup\$ @tomnexus This might be true, I'll update my answer \$\endgroup\$ – Fusseldieb Sep 11 '17 at 18:27
  • \$\begingroup\$ Arduino FTW. Solves the signal conditioning and threshold decision problem. \$\endgroup\$ – tomnexus Sep 11 '17 at 19:20

Not the answer you're looking for? Browse other questions tagged or ask your own question.