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Topic: Design issue - How to do? (Read 2820 times) previous topic - next topic

Michael L

I need some input on a design I'm working on. I need to do the following with the least amount of components, as space is an issue:

I have 3 input pins A, B and C. Two output pins 1 and 2.
And I need to achieve these three combinations:
A to 1 and B to 2
C to 1 and B to 2
A to 1 and C to 2

It needs to be controlled by an Arduino. I have been looking at NPN and PNP transistors, but it will require to many conponents.

Any thoughts?

CrossRoads

#1
Sep 03, 2011, 05:35 pm Last Edit: Sep 03, 2011, 05:37 pm by CrossRoads Reason: 1
So you want the outputs to mimic the inputs under those three sets of  conditions?
Example
Code: [Select]

switch (ABCselect){
Case 1:
digitalWrite (output1, digitalRead(inputA));
digitalWrite (output2, digitalRead(inputB));
break;
Case 2:
digitalWrite (output1, digitalRead(inputC));
digitalWrite (output2, digitalRead(inputB));
break;
Case 3:
digitalWrite (output1, digitalRead(inputA));
digitalWrite (output2, digitalRead(inputC));
break;
}

Or you need to have outputs = inputs as analog signals?
Your question needs to be more clear.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

Michael L

Quote
Your question needs to be more clear.


Yes. I just thought of that. Imagine a DPDT relay. I need something like it but a Double Pole Triple Throw instead. A, B and C is 16v, 10v and Ground. I need it routed to the outputs, 1 and 2, using the Arduino to do the controlling.

Better? Otherwise, I think I can draw it.. Not sure, though...

Graynomad

#3
Sep 03, 2011, 05:42 pm Last Edit: Sep 03, 2011, 05:46 pm by Graynomad Reason: 1
You can use transmission gates like the 4066, they will work with digital or analogue but as Crossroads says, need more info.

Voltage levels.
Current levels.
Analogue/digital.
Speed of signals.
Speed of changing from one setup to another.

and probably some other stuff I haven't thought of.

EDIT: Crossed there, you need 4 SPST relays.

A only ever goes to 1 (SPST)
B only ever goes to 2 (SPST)
C can go to either   (2 x SPST)

_____
Rob
Rob Gray aka the GRAYnomad www.robgray.com

Graynomad

Another question, how important is it that another combination is NOT selected?

You can control the relays with 4 Arduino outputs but if it's a big problem say for A to be connected to 2 then I may add some logic because it's easy to stuff up the programming.

_____
Rob
Rob Gray aka the GRAYnomad www.robgray.com

CrossRoads

#5
Sep 03, 2011, 06:07 pm Last Edit: Sep 03, 2011, 06:10 pm by CrossRoads Reason: 1
4 Simple 5V/low coil current relays could be controlled by arduino outputs like this:
Be sure to have software open relays before closing others.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

Michael L

I already thought of the solution with four relays (or even two DPDT), but I have space issues - But perhaps, some of you can find some small relays?

Graynomad

You could use solid state relays (like the CPC1014N), they come in a 4x4mm package but only 400mA capacity.

That's why I asked the questions above.

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

CrossRoads

#8
Sep 03, 2011, 06:15 pm Last Edit: Sep 03, 2011, 06:18 pm by CrossRoads Reason: 1
Is SUBMiniature small enough for you?
http://www.mpja.com/prodinfo.asp?number=18474+RL
Takes up the space of a 16 pin DIP
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

CrossRoads

http://www.components.omron.com/components/web/pdflib.nsf/0/51A3390695AC774885257201007DD58D/$file/G6L_0310.pdf
Found these at Digikey, even smaller.
Search for relay, Signal, filter your way down: in stock, thru hole, non-latching, 4.5V coil
Lot of options.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

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