stenseltizm

Basically I need to find a chip.


I need to control two analog devices with the same 1-5V output from a controller, but not at the same time.

I need the one not in use to recieve a voltage slightly less than 1 volt so it is essentially turned off when not in use. I have to supply the relays with at least the <1V as they are PID controllers and they can get a little weird when the setpoint is disconnected completely or suddenly returned.

I can schematically draw what I want using a DPDT relay, but I'm sure there are solid state chips designed to do this without all the noise and spikes that would be involved in using a mechanical relay. Plus it would make my life easier to be able to control this with a 5V digital signal.

The normally Closed contact of the first circuit would be 1-5V for the 1st analog device,
the Normally Open contact of the first circuit would be the <1V for the 1st analog device,
and the Common of the first circuit would go to the 1st analog device.

The normally Closed contact of the second circuit would be <1V for the 2nd analog device,
the Normally Open contact of the second circuit would be the 1-5Vsignal for the 2nd analog device,
and the Common of the second circuit would go to the 2nd analog device.

So at rest the 1st analog device gets the 1-5V signal and the 2nd analog device gets <1V,
when energized the 2nd analog device gets the 1-5V signal and the 1st analog device gets <1V.



I'm willing to throw someone a few bucks to send me a link to an easily purchased through hole mounted chip from like mouser, digikey, newark etc.
It has to be useful to me to pay.

Tom-Guy

You want TTL logic.

stenseltizm

sadly the only thing I know about electronics is what i've been forced to learn through google and errors fixing what I paid other people to design build etc.

ie I don't know what i need.

I have an op amp (i think) conditioning a pwm output into a stable 1-5v output.
I need to toggle which device gets this output, and a .9V output I can make with a simple voltage divider.

I want it to do so without the moving parts of a relay, a solid state ic chip is what I'm visualizing

Tom-Guy

Opamps aren't difficult, but you have to understand them and they might be a bit much for you to learn.

Uhm, see if you can't find a TTL logic reed switch? I'll have a look later tonight.

stenseltizm

my searching always turns up components like this:
http://www.analog.com/en/analog-sign...ons/index.html
http://www.analog.com/static/importe...ts/SSM2404.pdf
http://www.analog.com/en/switchesmul....html#Diagrams

and all kinds of CMOS and other switches that look like they could do what I want, but i'm not sure what half of the datasheet means.

stealthiskey

comparator?

basically an opamp with infinite gain so any v lower than the ref voltage in outputs the low rail (could be 1V) and any v higher than the ref outputs the high rail (could be 1v-5v). Could get an ic with like 4 comparators in it.

stenseltizm

Bump. It's getting closer to the time I design this machine, would like to get a couple chips ordered to play with but still don't think I know enough to start pulling parts out of a catalog.

I read this 5 times and it made more sense a little. At first I thought you meant it would only output a high or low voltage, but I think I see what you mean. I'll look into it unless you got some specific datasheets or even part numbers that I need to google datasheets on you could spoon me.
Thanks

stealthiskey

I made you a mspaint. Pictured are opamps, but comparators should work as well. The + and - are the two inputs to the opamps. in the case of a comparator one will be labelled Vref, the other Vin or something, just treat them the same as here.

hmtcirc.jpg?t=1235607337

LM311 is a common comparator, there are probably others that are better suited. I'll look into it, maybe.
In this case you will need to create a Vref signal (unchanging). It can be any reasonable voltage you wish. Then the Vswitch signal will be what you use to control the switching of outputs. When it is below Vref the outputs will be one condition, when it rises above Vref the outputs will flip.

The key here is that the inputs to + and - (Vref and Vswitch) are flipped for the two opamps/comparators. This means the outputs will do opposite of each other.

stenseltizm

**** I have some op amps imma test this out in the next week or so. pm me your paypal

stealthiskey

nah don't worry about that, just let me know how it goes.

For Vref and Vswitch you may be required to use voltages in between the two rails (V+ [1to5] and V- [1]). So try 1.5 or so to start.