Voltage translation from 3.8v to 5-24 vdc at DC to 24kHZ

Here is a decent article on this:

https://electronics.stackexchange.com/questions/242094/how-to-amplify-a-25khz-square-wave-that-goes-from-3-3v-to-3-3v-so-that-the-amp

Remember that you need a good frequency response of the amplifier to ensure the square wave remains reasonably square.

Then you need a boost converter http://www.ti.com/lit/an/slva372c/slva372c.pdf
Theory
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Note that I need DC to 25Khz, this level in some cases will be steady state DC for a long time. It will be driving a stepper motor driver module so frequency of the pulses will change a lot.

I was thinking something along the ULN2003 type of circuit but with a better response. If the swing is up to 15 volts then I can live with rounded corners.

So you need a DC to Wideband amplifier as the square wave will have (I think) nothing longer than a 50 nanosecond rise time (or it is not very square)

Could you suggest one for a hobbiest level person like myself? The less external components the better.

You can go to an electronics store to ask about amplifiers.  That is what I would do.

You can get amplifier kits but you would need to ensure the resulting product works for you.

Those hardly exist anymore round here.  I'm amplifying" a digital signal. Seems like there should be a simple method like an opto isolator. I'll keep digging.

Opto Isolators just isolate signals. I have these in my B&K Oscilloscope so it can work with small voltages up to 500 Volts above ground.

Go to Google and look up Online Electronics Stores.  I do that but all the hits are around here so you can find them closer to you

Oh, you're driving a stepper motor with it.  There's a range of modules on fleabay that will do the job for a few dollars.

https://www.ebay.com/sch/i.html?_nkw=arduino+stepper+driver&_sop=15&_pgn=3

Since these are Arduino modules they are generally compatible with 3.3V I/O.  Some are I2C, some are direct digital I/O, you should be able to find something suitable

No, not a motor, a motor driver.  Actually a Clearpath motor from Teknic which has the drive circuitry built in and uses an input signal for step and direction. They require a 5-24 volt input, but the driving board signal is only 3.8 to 4 volts as seen on a scope. The motor still works but its under its stated tolerance and obviously thats not a good situation, I want to boost it up to normal levels above 5v.

That is why you need a good amplifier for this considering the bandwidth needs you have. Look through the online electronic stores for such a device

A ULN2003 was what I was considering from the start and all these use that part. Guess I was on to something after all.

I was concerned that since I'm basically driving an LED, there wouldn't be enough current drawn to allow it to turn off. 2003's are generally thought to be for more current than I have. But its easy enough to try.