Momentary water pump switch

[Harvey Babb]

I stand by my post. If you connect the resistor and an LED and apply 120 volts the LED will be instantly destroyed by excess reverse voltage. 

Putting a diode in series with the LED-resistor combo will protect the LED from high reverse voltage allowing it to operate safely, as would connecting the LED and diode in reverse parallel so that reverse voltage is shunted around the LED.

Yes, the resistor will dissipate quite a bit of power and will need to be sized appropriately. I did not (and would not) suggest that this was a good solution; I only wanted to point out using the LED-resistor combo would destroy the LED.

A better solution that eliminates most of the wasted power is described here: https://electronicsarea.com/light-emitting-diode-connected-to-120-240-vac/ where a capacitor is used used as the primary current limiting device.

 

 

[Dr4Film]

I rebuilt a Carling Technology switch used for the Aqua-Hot diesel burner which is lit up most of the time with a White LED. The tried a variety of resistors at different ohms to get the brightness where I liked it. I can't remember exactly what value it was though.

On 12/27/2020 at 5:27 PM, Moonwink said:

For anyone looking for this type of indicator lamp, I have a bunch left over which I removed after installing the LED ones. You are welcome to have them for the cost of shipping from 32136.

[dl_racing427]

21 hours ago, Harvey Babb said:

I stand by my post. If you connect the resistor and an LED and apply 120 volts the LED will be instantly destroyed by excess reverse voltage. 

Putting a diode in series with the LED-resistor combo will protect the LED from high reverse voltage allowing it to operate safely, as would connecting the LED and diode in reverse parallel so that reverse voltage is shunted around the LED.

Yes, the resistor will dissipate quite a bit of power and will need to be sized appropriately. I did not (and would not) suggest that this was a good solution; I only wanted to point out using the LED-resistor combo would destroy the LED.

A better solution that eliminates most of the wasted power is described here: https://electronicsarea.com/light-emitting-diode-connected-to-120-240-vac/ where a capacitor is used used as the primary current limiting device.

 

 

That capacitive circuit is a good idea.
I've never had to adapt an LED to 120v, but that is a lot more efficient.