Matt Ormsby wrote:

> I ran into a small problem with a circuit and was hoping for some help.  I
> have an output from another device of which runs 1.1 volts on to 0 volts

Let me add my voice to the many...

You don't state the impedance of the output in the LOW as well as HIGH
states. The HIGH voltage suggests a single cell battery operated device.
But, for all we know, the output could be modelled as a high impedance
pullup to B+, with an open collector (low impedance) switched to GND
when in the LOW state.

If this is the case, then a PNP transistor can be used to convert
voltages. The base is connected to the signal through a base current
limiting resistor. The emitter is connected to your circuit's V+, and
the collector switches ON when the signal is LOW. Use a low gain
transistor to ensure that it switches off even though some current may
be flowing into the output device when it is HIGH (if V+ > 1.1V). In
some ways this is a better approach than using a common emitter circuit
if such a circuit is not deeply switched into saturation (saturation is
when Ic < Ib X Beta). Making sure that each transistor stage switches
into saturation (and conversly into cutoff) will provide for stable
circuit operation across a wide temperature range and with production
variances.

If this is not appropriate to your application please describe the
device's output characteristics parametrically (impedances, etc.) or by
model (simplified schematic).

--
Regards, Dana Frank Raymond