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Measure a Bipolar Signal with an Arduino Board
Sunday, August 14th, 2011Summary:
Arduino is a popular family of open source microcontroller boards. Hobbyists, students and engineers all over the world use this platform to quickly design and prototype a microcontroller driven circuit. One of its interfaces with the analog world is the ADC. Since these boards are mostly designed around an ATMEL ATmega32 or ATmega168 microcontroller, the ADC has 8 inputs and 10-bit resolution, making it suitable for many applications.
Measure a Wheatstone Bridge Sensor Signal with an ADC
Saturday, July 23rd, 2011Summary:
I received a message from one of my readers asking me to help with a Wheatstone bridge circuit. Since my response to him bounced back, and this being an interesting subject, I decided to write this article. Here is what he writes:
Apply Thevenin’s Theorem to Solve a Negative Resistance Circuit, or Current Source
Monday, February 14th, 2011Summary:
The circuit in Figure 1 is a good example of applying Thevenin’s Theorem to solve a circuit with dependent supplies. It is a negative resistance circuit and it was posted in this forum with a call for solution verification for IL as a function of Vin. Since this fits very well with my plans to write more about Thevenin’s Theorem, I decided to post the solution here.
Using the Summing Amplifier as an Average Amplifier
Sunday, July 4th, 2010Summary:
The summing amplifier can output the average of two, three or more signals. This is different than a signal average. The summing amplifier cannot, for example, output the average of a triangle signal. For that, you need an integrator to perform the average in the analog realm, or you need to sample the signal and calculate the average with a microcontroller. This type of average is the signal average in the time domain. I will write an article about the average of a signal in a near future.
How to Design a Circuit from its Transfer Function Graph
Sunday, February 21st, 2010Summary:
Sometimes all we know about a circuit is its transfer function graph. The transfer function might look like the one in Figure 1. How can we design a circuit so that its input-output behavior will match the graph?
Design a Bipolar to Unipolar Converter with a 3-input Summing Amplifier
Sunday, January 31st, 2010Summary:
Since the publication of Design a Bipolar to Unipolar Converter to Drive an ADC, several readers contacted me with requests to help in solving their particular converter. The common problem they had was the fact that the components’ calculation resulted in a negative value for at least one resistor.
To provide a solution, first we need to understand the root cause of the problem. Let’s take one of the circuits I received and analyze it.
The reader wrote that he would like to drive an ADC with the input range of 0 to 2.5V from a signal with the range of –5V to +5V, connected at V1.
Bipolar to Unipolar Converters Based on a Summing Amplifier Configuration
Monday, December 28th, 2009Summary:
In a previous article I presented a method for designing a bipolar to unipolar converter using a summing amplifier. In this article I am going to show more examples of bipolar to unipolar converters which are based on a summing amplifier configuration. You can adapt them to your needs if you use the method I described in the previous article.
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