---
title: "Essential Logic Families | Workbench Wednesdays #35"
description: "Did you know that TTL chips do not output 5 volts? 74LS, 74HC, and 74HCT all have different input and output thresholds. Switching between logic families can be difficult if…"
canonical: "https://www.baldengineer.com/essential-logic-families-workbench-wednesdays-35.html"
author: "James Lewis"
date: "2021-03-02T23:07:00Z"
lastmod: "2022-04-01T22:10:55Z"
categories: ["blog","element14","measurements","workbench-wednesdays","videos"]
tags: ["7400-series","cmos","oscilloscopes","ttl"]
---

# Essential Logic Families | Workbench Wednesdays #35


Did you know that TTL chips do not output 5 volts? 74LS, 74HC, and 74HCT all have different input and output thresholds. Switching between logic families can be difficult if you are not careful. In this video, learn how different 7400-series logic families compare with input threshold, output voltage, frequency, rise time, and propagation delay.

Check out this [TI Application Guide](https://www.ti.com/lit/sg/sdyu001ab/sdyu001ab.pdf?ts=1648812751723&ref_url=https%253A%252F%252Fwww.google.com%252F) for a great resource on logic families.