Hi,
I like the following switch with a led:
http://www.bulgin.co.uk/PDFs/Cat83_Pages/Bulgin_2010_p193.pdf
How should I connect the led terminals to a PSU with 12VDC? Do I need a resistor in series?
I have not found this information on the switch datasheet.
Thank you
northernsky
I like the following switch with a led:
http://www.bulgin.co.uk/PDFs/Cat83_Pages/Bulgin_2010_p193.pdf
How should I connect the led terminals to a PSU with 12VDC? Do I need a resistor in series?
I have not found this information on the switch datasheet.
Thank you
northernsky
If you look at the picture "Contact Layout" all the information is there in front of you.
The LED is just a "Raw" LED and will require a series resistor. If you assume that Vf will be about 1.2V and If about 5mA, then you will need a series resistor of 2K2.
The LED is just a "Raw" LED and will require a series resistor. If you assume that Vf will be about 1.2V and If about 5mA, then you will need a series resistor of 2K2.
Thank you KatieanDad: you simply gave me the information I was looking for!
northernsky
I stand corrected. If you look at the datasheet, the switch can be one of two types 12V or 220V. You will need to check which part number you are ordering.
The resistors will already be inside the switch.
MP0045/1E1/Colour/Voltage
/RD /GN /AM /BL = RED, GREEN, AMBER, BLUE
/012 /220 = 12VDC or 220VDC
The resistors will already be inside the switch.
MP0045/1E1/Colour/Voltage
/RD /GN /AM /BL = RED, GREEN, AMBER, BLUE
/012 /220 = 12VDC or 220VDC
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I have purchased those switches. The resistors are NOT inside the switch.
They require external resistors. I know from (and unfortunate) experience.
Why not test the LED using a series resistor? It won't hurt and will surely answer your question.
They require external resistors. I know from (and unfortunate) experience.
Why not test the LED using a series resistor? It won't hurt and will surely answer your question.
As FrankBerry states, it's quite easy to check.
Assume that the switch has no resistors in it and try 2K2 (the correct series resistor) in series with the LED connections. Even if the switch has the 2K2 resistor in it, the LED will still illuminate at 2mA. You can use Kirchoff's law to ascertain if the resistor in the switch is correct.
Assume that the switch has no resistors in it and try 2K2 (the correct series resistor) in series with the LED connections. Even if the switch has the 2K2 resistor in it, the LED will still illuminate at 2mA. You can use Kirchoff's law to ascertain if the resistor in the switch is correct.
KatieandDad is correct: there are two switches in the Mouser catalog (220VAC not available).
I also find confusing the datasheet: should I make all connections of the 12VDC switch (the only one available) to a 12VDC?
In my case it would be useless since my trafo primaries would always be on!
northernsky
If you assume that the LED is "raw" you can't go wrong.
Use a 2K2 in series with the LED, even if the switch already has a resistor in it the resulting 4K will more than likely still illuminate the LED.
Use a 2K2 in series with the LED, even if the switch already has a resistor in it the resulting 4K will more than likely still illuminate the LED.
I'm not sure about the 220VDC switch. Perhaps it contains an internal resistor.
I know that the 12VDC switches do not. I connected one of the switches to a 12 volt supply without a series resistor. The LED went 'FLASH' and that was it. A costly mistake. Their documentation should show schematics of the switches. It's very misleading. The LED is not a 12 volt LED. It's only a 12 volt LED with the addition of an external resistor.
I know that the 12VDC switches do not. I connected one of the switches to a 12 volt supply without a series resistor. The LED went 'FLASH' and that was it. A costly mistake. Their documentation should show schematics of the switches. It's very misleading. The LED is not a 12 volt LED. It's only a 12 volt LED with the addition of an external resistor.
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