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Bulgin switches

post #1 of 12
7/15/09 at 11:48pm
Thread Starter 
I'm checking what power switch I would use for my next project (maybe M3 + o11). I found stainless steel Bulgin pushbutton switches. They are very nice and some of them event include leds.

Reference:
16mm Switches

Question #1: OK that's a dummy one for most but I want to be certain: what's the difference from momentary type vs latching type switch? Could be with the momentary type you must keep your finger on the switch to keep it on?

Question #2: Some are built with illuminated ring and have led terminals. The specs don't tell anything about voltage and current requirements. Is the buit-in led include a current limiting resistor should be current limited by an external circuit? I suppose I may connect it to LED connector the o11. Right?
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post #2 of 12
7/15/09 at 11:51pm
1) Yes.
2) Read specs more carefully (as in the datasheet), info should be there. You add your own resistor. Yes, can connect to sigma11.
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post #3 of 12
7/16/09 at 12:08am
Thread Starter 
Thanks FallenAngel. On the Bulgin pdf still can't find the specs for the builtin LED, I must be blind . But I suppose with the common 10K resistor that should be fine.

16mm Bulgin PDF spec file
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post #4 of 12
7/16/09 at 12:28am
All it seems to say is 12V for /012 model and 220V for /220 model (220V LED? Hard to believe...) so I'd just assume a standard 10k will work, that is as long as you don't get the 220 model
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post #5 of 12
7/16/09 at 12:31am
Yep, it's in the datasheet:

LEDs
Colours Red Green Amber Blue Red Green Amber Blue
Part No. /RD /GN /AM /BL /RD /GN /AM /BL
Voltage 12V d.c. 220V d.c. 12V d.c. 220V d.c.
Part No. /012 /220 /012 /220

Of course spacing is messed up here but the gist is this:

MP0045/Model/Colour/Voltage

12V LED : /012 (this is the one you want)
220V LED : /220
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post #6 of 12
7/16/09 at 12:52am
From my brief research of flashlights, I am pretty sure that momentary switches turn on before the button clicks

So, if you were to have a flashlight with what they call a "forward clicky", which is also called a momentary switch, you can turn the light on quickly without pushing the switch in all the way. This means that if you want to turn it on briefly, you don't have to go "click click".

A reverse clicky, or a non-momentary switch makes you push it on all the way and then release before it will turn on.

I don't think I explain things very well. here is a quote from a DX review of a flashlight
"Forward Clicky works as a slight push will temporarily turn on the light, silently, pushing harder makes it click & stay on.
This switch [reverse clicky] is pushed, clicks, then released before it turns on. So for a brief illumination of something, it goes click, click. :-("
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post #7 of 12
7/16/09 at 12:59am
Very sweet looking switches.
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post #8 of 12
7/16/09 at 1:52am
If you're referring to the MP0045 series illuminated switches, the /012 version needs a 12VDC power source for the internal LED. It has a built-in current limiting resistor, so no external resistor is needed. If your σ11 is configured to output 24VDC, then you should put a 12V 1W zener diode in series (reverse biased) with the LED, so it "sees" only 12V. Too much voltage may burn out the LED.

A latching switch is "push-on, push-off" (when "on", the button is pressed in). A momentary switch is spring loaded and remain on only while you're pressing the switch. If you use a momentary switch, then additional circuitry is needed (e.g., see the ε24.
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post #9 of 12
7/16/09 at 2:00pm
Thread Starter 
Thanks guys!

I'll add a 12V zener on my BOM.

Edit: Actually I should instead find something close to 18V Zener since I plan a 30V (M3 split +15v/-15v) supply.
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post #10 of 12
7/16/09 at 4:16pm
The 18V zener you want is at mouser p/n: 1N4746A

I recently wired mine up this way (in case others have questions how to connect the contacts)

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post #11 of 12
9/28/09 at 2:22am
For the sigma 22 ±30V. Two 24V 1 watt zener diodes 512-1N4749A are needed to reduce the 60V to 12V? The sigma 22 schematic has a resistor on each side of the board mounted LED. So there is resistor x inside the switch. So I need to air wire a 2nd resistor x on the V- side of the switch?




I was planning on not installing the board mounted LED, R16, and R17. Instead use R16 and R17 for each of the zener diodes and use LED+ wire to the switch and air wire a resistor x between LED- and the switch.
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post #12 of 12
9/28/09 at 3:48am
You don't need to air wire any resistors, there is already a resistor inside the switch, so all you need is to drop 60V to 12V with the two 24V zeners. You can install the zeners in the σ22 R16/R17 locations. Note that in your picture, the bottom zener is backwards. The cathode should be on the right side.

Mount the zeners slightly elevated from the board surface because they will be warm.
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