How can I get a +1.8 volt to +4.2 volt square wave to match up with a TTL input?

ElectricAye

I hope some of you brainiacs are still awake at this hour. I've got a device outputting a square wave that runs from +1.8 volt to +4.2 volt at about 2 KHz to 5 KHz and I need to get that signal into a TTL input, in which the high is registered above 2.0 volts and the low is registered at below 0.8 volts. Any suggestions on how to do this without using amps? I thought about a voltage divider but the math doesn't work out right. So I thought about diodes in series, but I don't know if that would work or even if that would be safe.

Anybody still awake out there who might have a quick answer?

Phil Pilgrim (PhiPi)

Two diodes (1N4148 or 1N914) in series with a resistor sink to ground should to the trick.

-Phil

ElectricAye

Phil Pilgrim (PhiPi) wrote: »

Two diodes (1N4148 or 1N914) in series with a resistor sink to ground should to the trick.

-Phil

Awesome, Phil, thanks! I was hoping you were up tonight. 'Much obliged!

PJAllen

Drat, this diurnal lifestyle I lead.

http://www.falstad.com/circuit/e-dcrestoration.html

Publison

PJ Allen wrote: »

Drat, this diurnal lifestyle I lead.

http://www.falstad.com/circuit/e-dcrestoration.html

Darn you PJ. Every time you post I have to look up a new word.

Diurnal

ElectricAye

PJ Allen wrote: »

Drat, this diurnal lifestyle I lead....

Indeed, I can see how that might make things complicated for you.