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Replacement for rotary Switches

jimmykk

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Hi
I have used Rotary Switches: MRK206-A DP6T ( https://www.digikey.com/en/products...A/1048317?s=N4IgTCBcDaILYCcDWYAMA2AtAQxAXQF8g ) and M2012SS1W03 SPDT ( https://www.digikey.com/en/products/detail/nkk-switches/M2012SS1W03/1006881 ) for selecting different channels during a test setup.
Now i want to replace these rotary switches with an electrically controlled switch so that I do not have to change the channels manually. The voltage and current ratings of the new switches should be the same as mentioned in the datasheets above.
So wondering what are the best options here ? Any help appreciated here.
 

wwfeldman

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you might try this

since the mechanical switch is DP6T, you may need two, one for each of the two poles.
 

KlausST

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Hi,

you may use the datasheet values...
But I think the better way is to choose the values according signal requirements.
Often a mechanical switch has drawbacks against an semiconductor switch, but for sure it has benefits, too.

Btw: every electronic parts distributor and every analog switch manufacturer has online selection tools. They are for you and are for free, so use them

Klaus
 

crutschow

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Are all the switched signal peak voltages within the supply voltage and ground of the switch?
They must be to use a CMOS switch.
 

BradtheRad

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A transistor can gate a signal. This simulation has a PNP switching a signal On & Off. (An NPN might be used but signal path seems easier to manage with a PNP.)

The signal occupies positive polarity. If necessary you can mix it with a positive or negative voltage through a potentiometer to shift its level up or down.

Bias voltage needs to accommodate the limits of signal voltage. Ground the bias to turn on the PNP. Apply peak voltage of signal to turn it off.

PNP gates 20V signal turned On-Off by 20V bias .png

Use a transistor for each channel. Or use a half-bridge for a signal that is bipolar.
Or consider using a relay for channels that can only be switched by metal contacts.
 

jimmykk

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Are all the switched signal peak voltages within the supply voltage and ground of the switch?
They must be to use a CMOS switch.
No, they are between +2.5V and -2.5V. I found ADG1604 as SP4T Switch which has quite a low ON resistance as mechanical switches also had less than 0.1 Ohm resistance. But unable to find any suitable SP6T or DP6T Switch with around 1 ohm resistance. All the ones i have found are around 3 Ohm ON resistance.
 

wwfeldman

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what do you do with the signal after the switch?
is the low resistance necessary?

SP4T means you need 4 - 2 to cover the 6 switch positions and 2 to cover the DP
and a well designed selector circuit, to select the appropriate 6 out of 8.
 

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