## 1 MHz frequency counter using discrete CMOS ICs

Miguel Pedroso constructed a digital frequency counter using CMOS 4000 series logic chips to participate in the Dangerous Prototypes’ 2012 Open 7400 contest. It can measure frequencies up to 999.999 KHz.

Frequency counter using CMOS 4000 series logic chips

The project uses six 4029 4-bit counter ICs that are cascaded and configured to work in the BCD decade up counters. The measured frequency is displayed on six 7-segment LEDs, each driven by the 4511 BCD-to-Seven segment driver chip.

## A new multi-function power supply unit for my Embedded Lab

One important parameter in embedded system designing is power consumption. This parameter is directly related to the battery lifetime, if the system is to be powered from a battery. In order to determine the power rating of your designed system, you need to know how much current the system draws from the source at a given voltage. While working on my projects, I usually measure current by placing an external ammeter in series with the current’s return path. This is not always convenient to do, and so I thought of making a special power supply unit for my lab that would display both voltage and current information on a LCD screen while prototyping my circuit. This way I can continuously monitor how much power my test circuit is drawing at a specific operating voltage.

Multifunction bench power supply

## A brief tutorial on frequency measurements

Measuring the frequency of a signal may seem to be a simple process of counting pulses, but in order to get better accuracy, few other things should be considered, such as the gating interval and the range of measurement. This tutorial, posted on the pcbheaven.com, briefly describes two typical methods of frequency measurement: Direct Frequency Measuring (DFM) and the Reverse Frequency Measuring (RFM), with their pros and cons.

The shape of the incoming signal may be distorted and of varying amplitude. Therefore, some sort of signal conditioning along with a voltage limiter is required prior to the frequency counter circuit.