I might have tried almost all (cheap) options:
1. Cheap Aldi extractor with power take off
- returned, because it did not start for some lower power tools (e.g. jig saw)
2. Intelliplug from Peter Millard video linked above
- there is a delay about 5 or 6 seconds before it activates Slave power. I found it unusable, especially with mitre saw
3. Master and Slave Auto Power-Off IEC - linked in MorrisWoodman12 message above
- when it works - it works great.
I bought two.
- First (vacuum connected directly to Slave socket) broke down within 1 week.
- Second (vacuum wired via contactor) lasted 3 or 4 weeks
4. My current setup: DC Current Detection Sensor Module 5V + contactor - has been in constant use for 5 to 6 months and has not failed so far
- current detection module (current price: £5.70)
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DC Current Detection Sensor Module 5V/12V/24V Relay Protection Module | eBay
- contactor (current price: £9.71)
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British General Fortress 20A DP Contactor NO
On the master side I have 1 m extension lead with 2 sockets
- First socket for plug-it style power cord (all my tools have appropriate adapter)
--- when tool turns on - vacuum turns on automatically
------ It even works with the mitre saw light correctly. i.e. does not turn vacuum on until the blade is started.
- Second socket with LED light wired via pull cord. When cord is pulled - light turns ON and vacuum starts.
This way I have the best of both worlds - vacuum can be started either automatically or manually (for tools not using plug-it)
When I implemented option 4 I did consider KEMO M103N, but since I already had contactor wired 5V DC detection module was a cheaper option.
FYI - If using KEMO M103N - there is a video covering the process.
It is in German, but allows to enable English captions
In case anyone curious how to wire 5V DC detection module:
- note - these modules can be 5V or 12V or 24V. Make sure to select the right one depending on what power supply you have. I had 5V from mobile phone. Pictured below is 12V.
- If you find that your lower powered device is not detected - wrap more than 1 coil of wire via the detection coil