Author Topic: Using an AC Circuit to Turn on Another AC Circuit  (Read 4476 times)

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Offline dellsam34Topic starter

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Using an AC Circuit to Turn on Another AC Circuit
« on: January 20, 2025, 05:26:09 am »
I'm looking for an idiot proof solution, The problem is, everytime someone is cooking using the stove's hot plate they always forget to turn on the range fan to extract vapors and fumes resulting in a smelly house unless all the windows are opened. My initial thought in solving this issue is to build a clamp amp or amp probe around one of the stove power cord wires and use that as a trigger to turn on the range fan so that way as soon as the stove is turned on, the range fan comes on. I'm in the US, the stove runs out of 220VAC and the range fan runs out of 110VAC. I'm not really into electronic circuit design, but I'm open for pre designed circuits or a DIY ready product, I just haven't been able to find what I'm looking for using google search.
« Last Edit: January 20, 2025, 05:28:12 am by dellsam34 »
 


Offline WattsThat

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Re: Using an AC Circuit to Turn on Another AC Circuit
« Reply #2 on: January 20, 2025, 05:56:22 am »
Just be aware that the output of the current sensor is “pilot duty” meaning you do not want to control a fan directly with the normally open contact as it is only rated for 2.5 amps. You’ll want to drive a relay with contacts rated for the fan amperage. Keep in mind many AC motors draw 5-10 times higher amps for a brief time at startup, this drops to the rated amps once they reach rated speed.

Here’s a 30 amp rely:

www.amazon.com/Tnisesm-Mounting-Connect-Terminals-HF105F-4-AC120V-8X/dp/B087G3FWVT/ref=sr_1_21

« Last Edit: January 20, 2025, 05:58:56 am by WattsThat »
 

Offline inse

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Re: Using an AC Circuit to Turn on Another AC Circuit
« Reply #3 on: January 20, 2025, 06:20:18 am »
If the hot plate has a physical switch, you could just tap there to control a relay with the right coil voltage or use a capacitive dropper.
If there was a „hot“ indicator, that would be an even better place to tap into.
In case the hot plate is thermostat controlled, the current detection method will cycle the fan as it does for the cooking plate.
« Last Edit: January 20, 2025, 06:44:09 am by inse »
 

Offline PCB.Wiz

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Re: Using an AC Circuit to Turn on Another AC Circuit
« Reply #4 on: January 20, 2025, 08:33:11 am »
I'm looking for an idiot proof solution, The problem is, everytime someone is cooking using the stove's hot plate they always forget to turn on the range fan to extract vapors and fumes resulting in a smelly house unless all the windows are opened. My initial thought in solving this issue is to build a clamp amp or amp probe around one of the stove power cord wires and use that as a trigger to turn on the range fan so that way as soon as the stove is turned on, the range fan comes on. I'm in the US, the stove runs out of 220VAC and the range fan runs out of 110VAC. I'm not really into electronic circuit design, but I'm open for pre designed circuits or a DIY ready product, I just haven't been able to find what I'm looking for using google search.

For a similar problem, I used a Solid State Relay, with a series resistor as the source 230V load (rangehood lights) was only single digit watts rated.
( I was not sure how the capacitive dropper would affect that)
I found a SSR with a 230V input (not common, but they do exist) - come in 10A, and mine was Ok to switch a modest load of 4 slave lamps.
It should be fine with your extractor fan, also a modest load.
 

Online NiHaoMike

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Re: Using an AC Circuit to Turn on Another AC Circuit
« Reply #5 on: January 20, 2025, 01:38:45 pm »
How about some temperature sensors or a thermostat to turn the fan on if the area below is well above room temperature?
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Offline dellsam34Topic starter

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Re: Using an AC Circuit to Turn on Another AC Circuit
« Reply #6 on: January 20, 2025, 08:57:48 pm »
@WattsThat: Good tip, thanks for the heads up.
@inse: That's out of the question.
@NiHaoMike: That's an interesting idea, This will allow the fan to keep working few minutes later to completely extract everything. Plus everything will be tacked in the range housing, no external wires, I think I may have to go this route, do you have any recommendations?
« Last Edit: January 20, 2025, 09:00:27 pm by dellsam34 »
 

Offline PCB.Wiz

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Re: Using an AC Circuit to Turn on Another AC Circuit
« Reply #7 on: January 21, 2025, 03:32:21 am »
This example has a relay, and a delay timer.
https://www.aliexpress.com/item/1005005110922247.html
 

Offline dellsam34Topic starter

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Re: Using an AC Circuit to Turn on Another AC Circuit
« Reply #8 on: January 21, 2025, 07:37:57 am »
This example has a relay, and a delay timer.
https://www.aliexpress.com/item/1005005110922247.html
I don't think I will be needing that, The relay linked above is much better.

Offline Poroit

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Re: Using an AC Circuit to Turn on Another AC Circuit
« Reply #9 on: January 21, 2025, 07:47:11 am »
G'day dellsam34,

Maybe you can adapt a W1209 LED Temperature Controller 12V NTC Sensor Red Display Temperature Control Range - 50-110 ° C Relay Output.

Just watch the response time of the sensor.

You may need to remove the metal cover (if possible) or source your own bead thermistor so that the fan does not run for to long after the stove is turned off.
 

Offline dellsam34Topic starter

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Re: Using an AC Circuit to Turn on Another AC Circuit
« Reply #10 on: January 21, 2025, 07:51:38 am »
« Last Edit: January 21, 2025, 07:53:23 am by dellsam34 »
 

Offline inse

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Re: Using an AC Circuit to Turn on Another AC Circuit
« Reply #11 on: January 21, 2025, 08:36:39 am »
Don’t know if this is going to work.
If you mount it close to the cooker hood, it might cycle on and off during cooking as temperature would drop when the fan starts running.
You need something to detect heat radiation
 

Offline dellsam34Topic starter

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Re: Using an AC Circuit to Turn on Another AC Circuit
« Reply #12 on: January 22, 2025, 08:07:09 am »
I will see if I can extend the heat sensor to a location not affected by the fan's air flow.

Offline inse

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Re: Using an AC Circuit to Turn on Another AC Circuit
« Reply #13 on: January 22, 2025, 09:07:03 am »
Make sure the sensor is either galvanically isolated or take care you insulate it accordingly.
I still don’t regard it a promising approach.
 

Offline Langdon

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Re: Using an AC Circuit to Turn on Another AC Circuit
« Reply #14 on: January 23, 2025, 04:04:21 pm »
AC relays do exist.


I have seen 120VAC relays.

They are not that common, but not that uncommon either.

Old-school Air Conditioning units use a 24VAC to switch the Compressor (and possibly also the fan) on.

You can just use a 24V transformer and a 24VAC relay.

Or you can just use 3 diodes, a resistor (to reduce the voltage a tad), and a DC relay.

You can get away with 1 diode, but 3 is better.

Example circuit:

Connect "AC Neutral" to the "negative" or "positive output" of a rectifier diode, and connect the other pin of the diode to one pin of the relay coil.

Connect "AC line" to the "positive input" of a second diode.

Connect a resistor (about 10Ω) between the unconnected pin of the second diode and the unconnected pin of the relay coil to reduce the voltage (the voltage of rectified DCreachs the AC voltage times the square root of 2). (24VAC rectifies to as high as 34VDC)

Connect a third diode facing "backwards" across the relay terminals to deal with the inductive reverse voltage released by the relay coil.

This could be done with just 1 diode and a resistor, but the 3 diode approach is probably safer (the diodes block half the AC) and more efficient (reverse voltage is shorted by the diode for free, instead of contributing to the power consumption of the device)
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Offline dellsam34Topic starter

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Re: Using an AC Circuit to Turn on Another AC Circuit
« Reply #15 on: January 23, 2025, 06:05:57 pm »
AC relays do exist.


I have seen 120VAC relays.

They are not that common, but not that uncommon either.

Old-school Air Conditioning units use a 24VAC to switch the Compressor (and possibly also the fan) on.

You can just use a 24V transformer and a 24VAC relay.

Or you can just use 3 diodes, a resistor (to reduce the voltage a tad), and a DC relay.

You can get away with 1 diode, but 3 is better.

Example circuit:

Connect "AC Neutral" to the "negative" or "positive output" of a rectifier diode, and connect the other pin of the diode to one pin of the relay coil.

Connect "AC line" to the "positive input" of a second diode.

Connect a resistor (about 10Ω) between the unconnected pin of the second diode and the unconnected pin of the relay coil to reduce the voltage (the voltage of rectified DCreachs the AC voltage times the square root of 2). (24VAC rectifies to as high as 34VDC)

Connect a third diode facing "backwards" across the relay terminals to deal with the inductive reverse voltage released by the relay coil.

This could be done with just 1 diode and a resistor, but the 3 diode approach is probably safer (the diodes block half the AC) and more efficient (reverse voltage is shorted by the diode for free, instead of contributing to the power consumption of the device)

I don't quite understand your post, I'm looking for a way to sense the current without modifying the 220V circuit for the stove or interrupting it. I have no clue how you implement what you are talking about without chopping off the 220V wires and inserting such components. A schematic may help illustrate your approach but I don't think it fullfills my need.
« Last Edit: January 23, 2025, 06:09:53 pm by dellsam34 »
 

Offline SteveThackery

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Re: Using an AC Circuit to Turn on Another AC Circuit
« Reply #16 on: January 24, 2025, 12:32:57 am »
I think I found what I'm looking for, What do you guys think?
https://us.amazon.com/Hipoilk-Thermostat-Temperature-Ventilators-Replacement/dp/B0DJY52TND?th=1

I don't see how you would use it. It appears to monitor the temperature of the air flowing around it, so where would you mount it to get a reliable switch-on as soon as the hotplate is working? And it's actually quite bulky - it'll be hard to put it somewhere out of sight, and yet still exposed to the heat from the hotplate.

I think detecting hot air might be tricky anyway, because the hotplate might not generate much air movement (especially if it's the infrared type) - the greatest output will be in the form of radiant heat. The device you linked will eventually respond to radiant heat because its outer case will warm up, warming up the air inside, but it's probably not going to be as responsive as you require.

As has already been said, detecting current flow in the hotplate will drive you nuts as the fan starts and stops in time with the thermostatically controlled hotplate element.

If it were me, I would I would use the "hot" indicator and tap off that. Does your stove have a "hot" indicator or not?
 

Offline dellsam34Topic starter

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Re: Using an AC Circuit to Turn on Another AC Circuit
« Reply #17 on: January 24, 2025, 07:25:06 am »
I don't need immediate response, The steam or fumes from cooking are not going to generate as soon as the hot plate is turned on, So a delay makes the process more efficient, Fan starts when heat is built up, and stops later after the heat and steam goes down even if the stove had already been turned off. I do have "Hot" indicator but I don't want any wires going in or out of the stove for safety purposes and I don't want any modifications to the stove. I just have to find a suitable location for the thermostat, maybe in the front control panel where the buttons are, this side is not directly exposed to the air flow and it receives a lot of heat from the top of the hot plate, If I can glue in the sensor probe with thermal paste to the inside surface of the stainless steel sheet metal.

Offline SteveThackery

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Re: Using an AC Circuit to Turn on Another AC Circuit
« Reply #18 on: January 24, 2025, 12:25:04 pm »
Understood. Let us know how you get on.
 

Offline zapta

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Re: Using an AC Circuit to Turn on Another AC Circuit
« Reply #19 on: January 24, 2025, 06:10:19 pm »
There are of the shelf master/slave switches where turning on the master device applies power to the slaves. For example

https://www.amazon.com/AblePower-Energy-Protector-Power-Managed/dp/B07DGLR17P
 

Offline dellsam34Topic starter

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Re: Using an AC Circuit to Turn on Another AC Circuit
« Reply #20 on: January 24, 2025, 09:45:42 pm »
That's 120V only, it won't work in my case.

Online Analog Kid

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Re: Using an AC Circuit to Turn on Another AC Circuit
« Reply #21 on: January 24, 2025, 10:10:19 pm »
Here's a switch I built to turn on a shop vac being used with a power tool (bandsaw) whenever the saw was in use:



It works really well.
The transformer came from a GFCI outlet. The incoming power just goes through the single large conductor.



The SSR I used is plenty beefy enough to handle your fan as a load.

Of course, to use this with your stove you'd have to connect the switch between a plug and a receptacle for the oven plug, assuming the stove isn't directly wired into a junction box. (You probably wouldn't want to cut open the stove cord, although you could do that.)

Maybe this'll help?
 

Offline inse

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Re: Using an AC Circuit to Turn on Another AC Circuit
« Reply #22 on: January 25, 2025, 04:59:54 am »
I don't want any wires going in or out of the stove for safety purposes and I don't want any modifications to the stove.
And how was this to be installed?

. … to build a clamp amp or amp probe around one of the stove power cord wires and use that as a trigger to turn on the range fan so that way as soon as the stove is turned on,
« Last Edit: January 25, 2025, 05:05:11 am by inse »
 

Online Analog Kid

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Re: Using an AC Circuit to Turn on Another AC Circuit
« Reply #23 on: January 25, 2025, 05:22:15 am »
My switch could be connected between the stove plug and the outlet, with a short pigtail with a plug. No modifications to anything (except maybe to the fan, which would have to somehow be plugged into the switch).

« Last Edit: January 25, 2025, 05:24:30 am by Analog Kid »
 

Offline dellsam34Topic starter

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Re: Using an AC Circuit to Turn on Another AC Circuit
« Reply #24 on: January 25, 2025, 07:45:14 am »
I don't want any wires going in or out of the stove for safety purposes and I don't want any modifications to the stove.
And how was this to be installed?

. … to build a clamp amp or amp probe around one of the stove power cord wires and use that as a trigger to turn on the range fan so that way as soon as the stove is turned on,

Around the stove wiring inside the cabinet, and goes up inside the cabinet then to the right but still inside the kitchen cabinets away from the stove cavity, I cannot modify the stove or have wires dangling behind it, I will be replacing it in a year or two, so I don't have to do it all over again.
« Last Edit: January 25, 2025, 07:49:31 am by dellsam34 »
 


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