A reed switch (if applicable) will simply close a battery powered circuit such as what you posted in post #1. You're not messing with 120VAC or any other high voltages. If the motor comes on and there's a magnetic field, the reed switch closes just to simulate the closure of the stopwatch button. Using the circuit you provided - the reed switch should be robust enough to handle that small current to turn the transistors on and off.

 

Here it comes - the two dumbest things I can think to ask:

1) how strong a magnetic field does the motor produce when running? If strong enough, it can close a reed switch.

Nowhere near enough, and anyway is all directed internally and would be swamped by the field from the permanent magnets in the surrounding stator (assuming the mu-metal shield around all of it doesn't hide the flux anyway).

The solenoid is the easiest for a hall sensor, I think I've found one that might work... But the easiest, ie least invasive, way to handle the motor is a current transducer around the supply lead, as it draws about 1/2amp

 

Have we determined the motor has a permanent magnet? And OK, if a hall effect is wanted - it, too, can be used.

 

Have we determined the motor has a permanent magnet? And OK, if a hall effect is wanted - it, too, can be used.

Small motor like that, its most likely. Could be a squirrel cage motor but, from memory, they don't have great starting torque and a pump needs that to get the water moving. In any case its very unlikely you'll find a large mag field outside the motor whatever form it is, as for efficiency you need it inside!

 

If it makes a difference, the pump is a vibratory pump.

 

Hmmm, you mean a diaphragm pump. Wonder if we could sense vibration?

 

Hmmm, you mean a diaphragm pump. Wonder if we could sense vibration?

Oh ya, lots of vibration. It vibrates enough that it's isolated by rubber mounts in the machine.

 

That might work well, could be worth an experiment.

Adafruit do this tiny sensor, basically a switch that closes when it's vibrated. Available through various outlets including Digikey (part # 1528-2166-ND )

Will need a little signal conditioning to drive that timer, but I think we can do better than a repurposed stopwatch anyway... will get back to you on that shortly...

As a first experiment you try and get one, and use a multimeter on the ohms/continuity setting to beep when the switch is closed. Bit of double sided tape to stick it to the motor housing and it should beep continuously when the motor is running and stop when it isn't. You may need to experiment with location and padding so moving stuff around the machine doesn't trigger it unexpectedly.

 

I've found that an oscilloscope is needed to monitor hits from a vibrating switch; multimeter showed no hits. An AC coupled tilt switch in horizontal position, gives a good output when
shaken. 'Just remembered that I have a small air pump that might resemble the water pumps
vibration, will try tomorrow.

 

The vibration of a diaphragm pump with an incompressible liquid is very different to that of an air pump.

Adafruit do three sensitivities of vibration switch, I suggested the medium. Looking at the data sheet of its acceleration (vibrating g-force) rating I'm reasonably sure it'll work. My bigger concern is differentiation, will it pick up, say, a cup being put on the machine? I think finding the right location actually on the motor will address both issues.

Ref multimeter, yes it will depend on its response. My Fluke would do so, its very fast on continuity.

 

I have managed to find a place that sells the Adafruit vibration sensor in Canada. I have ordered it and imagine it will arrive next week at which point I can test it and let you know if it works or not.

 

I have managed to find a place that sells the Adafruit vibration sensor in Canada. I have ordered it and imagine it will arrive next week at which point I can test it and let you know if it works or not.

On a multinational forum like this i think its useful to put your country at least into your profile so people know where you are. I tend to use digikey and mouser when quoting parts as they are available pretty much everywhere though I rarely buy from them as I have cheaper sources in the UK.

 

Another suggestion but slightly more complex is to use a specifically designed opto coupler like the HCPL3760.
You put mains voltage in one side and get a low voltage digital signal out the other.
The digital signal can drive whatever you like for example an LED or a relay.
I use them to interface with lighting timers that don't like working with LED lamp loads.

 

Another suggestion but slightly more complex is to use a specifically designed opto coupler like the HCPL3760.
You put mains voltage in one side and get a low voltage digital signal out the other.
The digital signal can drive whatever you like for example an LED or a relay.
I use them to interface with lighting timers that don't like working with LED lamp loads.

That was one of the earlier suggestions (see #6 & #8), but we've collectively moved to solutions that don't involve touching mains wiring...

 

Some place there is a logic level command telling either a relay or a triac to switch on the power to the pump.THAT signal can be used with a dual one-shot like the CD4528 0r cd4538 driving each section, one section connected to trigger on the rising edge and the other section connected to trigger on the falling edge. Then "OR" the two "Q"outputs and you have one short pulse at switch-on and another short pulse at switch off. The supply voltage for the ICs must match the supply voltage for the control logic. Then the "OR" signal can be across the stsrt/stop button, or it may need to be inverted.

 

Some place there is a logic level command telling either a relay or a triac to switch on the power to the pump.

The pump is a 120 volt vibration pump that I manually select on and off with a rocker switch. Here is the pump motor

 

I like what @MisterBill2 had to say about capturing a signal from whatever controls the pump. But what you said:

The pump is a 120 volt vibration pump that I manually select on and off with a rocker switch.

makes me want to ask for a complete schematic of the unit. If you have one, please provide.

You want to know the exact time the pump runs. I'm guessing something shuts it off at some point. If so then Bill may have the solution you want.

 

Attached is the schematic for the slightly older model, I cannot find the current one (Gaggia Classic Pro N.A. model). There is a slight difference in the front panel switches, but may be close enough to be of use?

 

You're overthinking it guys. Its a coffee machine. There's a basic manual rocker switch to turn the water on and off. The OP wants a simple way to start a timer when he turns the pump on so he knows when to turn it off, to get consistent run times. Yes we could jazz it up but that's not the immediate need. Once turned off the timer self resets after a few seconds....

 

And here is a video to give you an idea of what the operation looks like. The far left rocker switch turn the machine on to warm up the boiler, and the middle switch is the one that activates the pump, which is what I'm trying to time.