Logic switching - best circuit to make with these values?

[xcpointx]

given these values, what is the easiest solution?

Logic/input voltage parameters:
(can be one of these 2 options:)
switches between 0V and 0.61V
OR
switches between 0V and 4.98V

I have a -15V and 15V power source available.

I need to get that logic signal to switch an output signal between GROUND and -15V.

How can I do it?

[bioroids]

Hi!

with a 0v/0.61v control input signal, I think all you can use is a bipolar NPN transistor: the control signal to the base, the emmiter to ground, the collector to a resistor (1k-10k aprox). The resistor to the +15v supply. The output is at the collector, and is inverted (is high when the input is low and viceversa).
I think it should work, but be aware that there's some current flowing into the base, so it may affect the circuit that provides the control voltage.

Luck

Miguel
EDIT: sorry, I misread your post, the circuit I described will switch between ground and +15v. I think you can turn it around to switch between gnd and -15v, but it would need a -0.61 control

[gez]

switches between 0V and 4.98V

I have a -15V and 15V power source available.

You could probably do this with  a 40107 chip (dual nand gate).  Run it from a 5V supply and use one of the output MOSFETs with a pullup resistor run at the higher 15V.  The MOSFETs have an open drain connection and can be wired up to higher voltages, so the chip can interface between logic level and higher voltages.

The 4.98V signal would be needed to switch the NAND gates.  Treat the -15V rail as ground and 0V as +15V.  

I haven't done this, but it would probably work.

[niftydog]

not sure I understand what you're asking for.  But standard TTL logic is 0V-5V, so 0V and 4.98V would seem to be the go if you plan on controling a logic device.

how much current is available from this 4.98V? It might be easier to find a low voltage relay? Or feed this signal into a transistor capable of providing enough current to drive a relay!?

When you say "switch an output signal between GROUND and -15V." does it "literally" have to be ground? Otherwise, what Miguel has suggested may work... except that you have to hook it to -15V.