\documentclass[10pt,a4paper]{article}
\font\oltteight=oltt8 scaled 1000
\font\olttnine=oltt9 scaled 1000
\font\olttten=oltt10 scaled 1000
\font\oltttwelve=oltt12 scaled 1000
\font\olvtt=olvtt10 scaled 1000
\newcommand{\Ligature}{%
\input test_alphabet.tex
}
\begin{document}

Computer Modern Roman:\\{\Ligature}

Typewriter Text 8pt:\\{\oltteight \Ligature}

Typewriter Text 9pt:\\{\olttnine \Ligature}

Typewriter Text 10pt:\\{\olttten \Ligature}

Typewriter Text 12pt:\\{\oltttwelve \Ligature}

Variable-Width Typewriter Text 10pt:\\{\olvtt \Ligature}

\end{document}