Comments on: Design a Bipolar to Unipolar Converter to Drive an ADC

By: Build Your Own Sourcemeter Using Arduino • Tech Projects

Build Your Own Sourcemeter Using Arduino • Tech Projects — Mon, 25 Sep 2023 06:47:56 +0000

[…] (0V to 1.1V). For a good explanation of using a summing amplifier for this type of conversion, see http://masteringelectronicsdesign.com/design-a-bipolar-to-unipolar-converter/. Note that it is important that these resistance values be fairly precise. Variations will result […]

By: Adrian S. Nastase

Adrian S. Nastase — Tue, 28 Feb 2023 00:58:04 +0000

In reply to Matteo.F. I do not understand your circuit requirements. What is your input voltage swing and what is the output voltage span?

By: Matteo.F

Matteo.F — Mon, 30 Jan 2023 15:16:58 +0000

hello, i’m having trouble with my circuit. i’m using Arduino to take the DC 5Volt, for the -5V to 5V i’m using an LFO Module which i can chose the Frequency. I’m tryng on the bredborad with a TL072cn but i have a strange Output, something like 7Volts. i’m also using a +12 -12 power supply for The OpAmp.

By: +/-5V to 0…5V and not failing for +/-12V – GrindSkills

+/-5V to 0…5V and not failing for +/-12V – GrindSkills — Sat, 07 May 2022 13:24:05 +0000

[…] This conversion is possible with the schematics found at https://masteringelectronicsdesign.com/design-a-bipolar-to-unipolar-converter/ […]

By: Adrian S. Nastase

Adrian S. Nastase — Sun, 26 Jul 2020 21:09:58 +0000

In reply to Bric B. As I understand it, when V1 = -12V, output is 0V and V1 = +12V, output is 4V Then the gain is output_span/input_span = (4-0)/(12-(-12)) = 4/24 = 0.167 So, if you choose R1 = R3 = 10k, R2 and R4 are 1.67k (choose the standard values 1.65k or 1.69k). With V2 = 0V, the output will swing -2V to +2V. So you need an offset of 2V. Therefore, make V2 = 2V. It is simpler to choose equal resistors R1 and R3, R2 and R4. You can also use my calculator published here: MasteringElectronicsDesign.com:Summing Amplifier Calculator.

By: Bric B

Bric B — Wed, 15 Jul 2020 19:34:25 +0000

Hi Adrian, thanks for the article. I am trying to convert a +/- 12V signal to 0-4V for use with an Arduino. I went through your procedure to design the summing amplifier, and I calculated the resistor values at R1 = 12K, R2 = 1K, R3 = 4.2K and R4 = 4.9K, with V2 = 1V. However, when I test the output range, I get -2V to +6V. I’ve triple checked the math and the circuit wiring, but I’m not seeing anything out of place. I’m using a TLO82 Dual BiFET OP Amp (I will eventually need to have six of the same circuit to handle 6 bipolar signals). Would imprecision in the resistor values cause such a large change in the expected outputs?

Thanks.

By: saurabh

saurabh — Thu, 09 Jul 2020 06:25:56 +0000

In reply to Adrian S. Nastase. thanks, very good explanation.

By: Adrian S. Nastase

Adrian S. Nastase — Mon, 20 May 2019 00:08:47 +0000

In reply to Arvind Agrahari. It looks like you need to increase the power supply. LM741 is not a rail-to-rail op amp. The power supply needs to be at least 3V higher than the maximum output voltage. Te negative supply has to be 3V lower than the minimum output voltage.

By: Arvind Agrahari

Arvind Agrahari — Sat, 18 May 2019 20:05:14 +0000

Hi, Adrian I am using 741 op-amp to convert bipolar ac signal to unipolar with range of +/- 100mv , but the output I got is non-linear. For example, when my input peak to peak is 30mv I got 180mv peak to peak as output and , when 100mv I got 240mv similarly for 1V peak to peak I got 1.2 V. Please suggest what to do to make output linear.
Thanks

By: Adrian S. Nastase

Adrian S. Nastase — Sun, 28 Apr 2019 02:38:37 +0000

In reply to long. Figure 1 shows a theoretic setup, to help with the understanding of the calculations. Figure 2 is a practical circuit. You already have +5V that you feed into ICL7760. Connect it to the positive supply pin of the op amp as well. And connect the output of ICL7760 to the negative supply pin of the op amp.