All,
I know there are some fantastic minds around here.
The picture shows my intent.
My question is: What is the definitively most simple circuit with the lowest component count required to replace the Question Mark?
(the question mark in the intent of the image, not the question mark in this question ).
Prizes for creativity. (Ok, maybe, depending on how creative…) 
I’m sure Casey can find some way to put a giant honkin’ motor on it…
How much current do you need to carry?
What you are looking for is called an H-bridge and you can find many single chip solutions. For small signal applications, an analog switch can also be used.
[edit] it also occurs to me that a quad NAND gate would also work: 74HC00
How quickly must the ?device? respond to a change in it’s input ? How much current must the 2 outputs be capable or sourcing and sinking ? Is there an implied ground wire also being input to the ?device? ? Or must the ground reference for the input be one of the output lines ? Put another way, is it truly a 3 “wire” device or 3 wires plus ground ? Do you prefer lowest part count over size, cost, reliability ?
Or a DPDT relay if it needs to carry "high" current. But that assumes I've got a implied, not shown, fixed ground reference.lyndon:
How much current do you need to carry?[edit] it also occurs to me that a quad NAND gate would also work: 74HC00
Yes, there is a ground on the output side, not shown.
Only needs to carry 100ma max.
Speed - non critical. State may change once every 2-4 minutes, response in less than 500ms is perfectly fine.
Then I’d use the [H-bridge..](H-Bridge Motor Driver 1A - COM-00315 - SparkFun Electronics)
So is this a good depiction ?t3kboi:
Yes, there is a ground on the output side, not shown.Only needs to carry 100ma max.
Speed - non critical. State may change once every 2-4 minutes, response in less than 500ms is perfectly fine.
If so the prior answers are good.
Yes
How about a wire from the top leg to the output.
Shown w/ In = 5v (relay de-energized)
(click on to open)
OK, back to this again - not really as simple as it seems…
In the original question, there is a SINGLE input, that can be at +5 or 0V - but TWO outputs that flip back and forth between +5V and 0V depending on the input.
Of the three proposed solutions, only the DPDT Relay achieves this using a single input. (I assume the the cylinder in the image is an inline current limiting resistor for the 5V supply?)
The H-Bridge, and the NAND (or multiple NAND) Solutions both require more than one input.
SO -
How can i reproduce the dpdt relay as a no moving parts solid state component? (preferably SMT).
Or to fix the H-Bridge and NAND solutions - what would go between the single input, and the two inputs needed for the NAND/H-bridges?
The rectangle in the relay diagram is the coil. GND on In turns on the relay
A DPDT relay is an H-bridge!
Again it all comes down to how much current this circuit has to be able to source and sink. As mentioned above one output *could* just be a wire from your input, while the other is simply an logic inverter. If a 7404 can't provide the current needed, perhaps this would do ...t3kboi:
How can i reproduce the dpdt relay as a no moving parts solid state component? (preferably SMT).
This looks perfect. Thanks!
Cureent is <100ma
