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Author Topic: Equivalent of a mechanical toggle switch  (Read 574 times)
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Colorado
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I have two signal wires (5V/50mA) that I need to switch between 4 receiving pins.  In its default state, I need it connecting to two pins and when fed a control signal, I need it to flip to the other two pins.  Much like a relay would, except I don't need the traditional "low side/high side" that a relay provides.  Right now I'm using a mechanical slider switch and I wonder if there's an electronic solution.
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If you could draw out the switching action required it may help define what would be the best/good choice.

Lefty
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Colorado
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This is the schematic for the mechanical slide switch I'm using now.  I wonder if there's an electronic equivalent that can be toggled with (a third) signal.

By the default, the signal lines are connected to pine 1 and 3 and when triggered it needs to switch to pins 2 and 4 (and remain there for as long as the control signal is present.  When that signal goes away, the switch needs to revert back to pins 1 and 3.)


* switch.png (2.99 KB, 385x248 - viewed 4 times.)
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Well that is a classic DPDT switching contact arrangement, so any small DC DPDT relay could be used to accomplish that action.

Lefty

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Colorado
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Yeah that's the thing.  I don't have a clue what I'm looking for ... when I look for relays on Mouser of DigiKey, I get these large things for switching high and low current.  Seems overkill.  And while that's a DPDT switch, I'm using two of them (one at an input side and one at an output side), so if I can get a 4PDT one with a single control signal, that would be much better.  I may be reaching too high here ...
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Actually, never mind, I do still need two separate switches.  So ignore what I said above about needing a 4PDT one ...
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Yeah that's the thing.  I don't have a clue what I'm looking for ... when I look for relays on Mouser of DigiKey, I get these large things for switching high and low current.  Seems overkill.  And while that's a DPDT switch, I'm using two of them (one at an input side and one at an output side), so if I can get a 4PDT one with a single control signal, that would be much better.  I may be reaching too high here ...

Probably not but you can use two DPDT relays with their coils wired in parallel and driven by a single switching transistor that then can be controlled by a single arduino output pin that will give you 4PDT action driven from one signal.

The physical size of a relay is usually an indication of how much current the contacts have to handle. You haven't stated but if they are of non high current signals then lots of small DC relays will work, for example:

http://www.allelectronics.com/make-a-store/item/RLY-532/5-VDC-DPDT-MINI-SIGNAL-RELAY-2A/1.html

Lefty

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What kind of voltages (and current) would be required, If you are just doing logic level (simple on/off) and small currents (no motors!) you could use logic gates, an and gate with your input and control line would work. If you need analogue switching you can get multiplexer/switch ICs, such as: http://uk.rs-online.com/web/p/multiplexer-switch-ics/0307200/ , again you just need to be careful with you max voltage/current.
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Toby just beat me on the suggestion of a 4066 IC (quad bilateral switch).
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Just note, on the 4066 the Ron resistance is a lot... don't know if this can be an issue for your application. (anywhere from  80R to 1050R depending on supply voltage, and IC variance)

If you use a relay (and a transistor or mosfet), your resistance could be as low as 0.16R. 

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