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I own an ice cream machine which is perfect, except it lacks a light so one can check the state of the process. The motor case would be the perfect place to install a white LED, which will consume just 20-50mA current.

My problem is: the motor is powered by 240V AC, as shown in the following three photos.

The Motor Case (open)

The open motor case

All Connections

Closeup of the connectors

The Label on the Motor

enter image description here

The label on the motor contains this text:

6020D 220-240V 50Hz
20W Class B
Zhongshan Donlim weili
Electrical.Ltd

There are four connectors, neutral N and phase L and two unknown 1 and 2 wires.

Question

What would be the safest way to power a 20-50mA white LED from these wires?

  • There is only enough space for an SMD LED. A regular indicator LED is too bulky.
  • I can easily create a custom PCB for the solution.
  • I can also create professional connectors and insulated cables.
  • The solution can be complicated and expensive, involving special chips and components.
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    \$\begingroup\$ How is a surface-mount LED supposed to provide any meaningful illumination from inside the motor housing? Is the housing translucent, or are you thinking of making tiny hole(s) or a clear window where the LEDs are placed? This sounds like a lot of work. \$\endgroup\$
    – rdtsc
    Commented Sep 17, 2019 at 21:26
  • \$\begingroup\$ @rdtsc I will add a small hole at the bottom side of the housing for the LED. \$\endgroup\$
    – Flovdis
    Commented Sep 17, 2019 at 21:47

2 Answers 2

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This motor has a nicely exposed coil.

If you wind some turns of wire around this coil, presto you get a transformer.

Just wind enough turns to get about 2 volts, and feed that to a red LED.If you want a color with a higher Vf, that'll need more turns, so more work. Add a resistor in series to limit the current. Wrap some Kapton tape around the coil to keep it neat.

The LED will also be isolated from mains. It will be driven with AC though. The usual reverse voltage for LEDs is 5V so it should be fine. You can put two SMD LEDs wired antiparallel too.

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The safest thing would be to get an IEC 61010 or UL rated indicator light that works at 220V to 240V. The indicator lights are built to handle the voltages. While you could find a large resistor and wire it to an LED by and this may not be safe due to an arcing hazard, proper distances need to be maintained.

Here is a list of potentially suitable indicator lights (or search at your local distributor for panel indicators). Some of them are LED's some are not.

You should be able to use the LED indicator light in parallel with the motor.

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  • \$\begingroup\$ This was my first idea, but there is not enough space for a regular indicator light. It has to be an SMD LED package. I will extend the question with this additional requirement. \$\endgroup\$
    – Flovdis
    Commented Sep 17, 2019 at 19:59
  • \$\begingroup\$ An SMD package will arc and not be safe, you should not use one, even with a resistor. All SMD LED's work with voltages lower than 12V \$\endgroup\$
    – Voltage Spike
    Commented Sep 17, 2019 at 20:01
  • \$\begingroup\$ I am absolutely aware of this. I would never just connect a LED directly to mains power using a resistor. My question is how to solve the problem in a safe way. It can be complicated and expensive. \$\endgroup\$
    – Flovdis
    Commented Sep 17, 2019 at 20:05
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    \$\begingroup\$ Use an indicator LED light, they are cheap, and they have been tested. If you use a DIY solution, then you have to worry about spacing, insulation, arcing and safety requirements. \$\endgroup\$
    – Voltage Spike
    Commented Sep 17, 2019 at 20:07
  • \$\begingroup\$ I am not sure about safe, however if there is room there may be a way to diassemble one of those pilot lights and use the board that is in them to create your indicator. My preference would be to take one with a wire lead and make an external indicator box and then you only have the wire leads added. Bulky on the outside but safe on the inside. \$\endgroup\$
    – Robert Fay
    Commented Sep 17, 2019 at 21:26

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