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How do you know if a switch is a working one or not?

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Flyback

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yes its 12v relay...the supply is 24V, and the drop across the 750R and the LED leaves 12V for the relay.
The relay does work in this circuit, ive tested it.
There were no 24V relays in stock, and with the 12v one, I can drive the led indicator too.
 

ronv

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If it is really wired like your schematic it's a shame; otherwise you could just up the current to see if it fixed it.
 

audioguru

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I see nothing wrong with the circuit.
The relay coil is 1.2k.
The resistor for the LED is 0.75k.
The supply to the circuit is 24V minus maybe 2V for a red LED.
Then the voltage across the relay coil is 13.5V which is fine. If the LED is a 3.5V blue one then the relay coil gets 12.0V which is perfect.
 

ronv

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No I think the circuit is ok. I was just thinking if the switch was first in the circuit we could up the current to 100 ma or so to see if it "fixed" his switches.
 

Flyback

Well-Known Member
i see your point, I am thinking of soldering 100n across the switch, and see if that produces the high momentary current at switch closing to make it close well.
 

ronv

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I think it needs to be across the relay, but then the extra current flows thru the led as well. That would get it up to 26 ma or so - probably wouldn't blow the led - 75 usec. is pretty short for a sliding switch - might help - who knows. :rolleyes:
 
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ChrisP58

Well-Known Member
I think K.I.S.S nailed the real problem back in post 2.

If you look at your datasheet for the SDC series, you see that each knob runs two switches. A NO and a NC switch. If you have the bottom two pins tied together, and your circuit is connected to the top two pins, then it will behave exactly like you describe. The combined switch will only be closed when the knob is somewhere in the middle when the NO switch has just started to close, while the NC switch is just about to open. But with the combined series switch pair, it will never be closed in either of the end positions.

For your purpose, you want to only use one half of the switch. Connect to two pins that are directly across from each other with 7.6mm spacing, not next to each other with 2.54mm spacing.
 

tvtech

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I think K.I.S.S nailed the real problem back in post 2.

If you look at your datasheet for the SDC series, you see that each knob runs two switches. A NO and a NC switch. If you have the bottom two pins tied together, and your circuit is connected to the top two pins, then it will behave exactly like you describe. The combined switch will only be closed when the knob is somewhere in the middle when the NO switch has just started to close, while the NC switch is just about to open. But with the combined series switch pair, it will never be closed in either of the end positions.

For your purpose, you want to only use one half of the switch. Connect to two pins that are directly across from each other with 7.6mm spacing, not next to each other with 2.54mm spacing.

Yip Chris. I reckon between you and KISS you have nailed the problem. All makes perfect sense now ;)

Funny hey, a simple thing like understanding a switch, can lead to all kinds of complex wrong answers from people trying to help.

Regards,
tvtech
 
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Flyback

Well-Known Member
For your purpose, you want to only use one half of the switch. Connect to two pins that are directly across from each other with 7.6mm spacing, not next to each other with 2.54mm spacing.
....yes, that's the way I am doing it, and it still doesn't work properly
 

tvtech

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Most Helpful Member
No more trying from me than.

I don't have a clue anymore. Time for me to stop guessing cause I hate it.

Regards,
tvtech
 
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