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Single power supply instrumentation amplifier using LM324 – I am trying to design an instrumentation amplifier using LM324 (since it works with single power supply (as per datasheet), it is cheap and available in
stock). However currently I am testing my circuit on Proteus, but I am not getting the calculated gain &/or output using a single power supply; whereas I am getting the calculated gain if I use a dual supply to opamp. It would be helpful if someone can shed some light on this and suggest the modification to use it on a single power supply. Read more
Measuring battery temperature – I need temperature sensors to measure battery cells’ temperature by one by. The cell is connected in series so I could not find a temperature sensor which resists at 17V or more. I looked at LM35, but I could not figure out how to I connect it to battery cells. Read more
Gain of inverting amplifier using op amp – I need to invert the polarity of the voltage across PT1000 from -0.548 V to +0.548 V using an OpAmp AD844 in unity gain inverting configuration. The output of the inverting amplifier is Vout = -(R2/R1) Vin, where R2 is the feedback resistance. If I use R1 = R2 = 1K Ohm, the output of the OpAmp is only 0.250 V which shows that gain approximately half instead of 1. To get approximately +0.548 V, I need to use R2 = 2.2 K Ω feedback resistor. I am wondering why the unity gain does not work to convert -0.548 V to +0.548 V? Read more
Design of directional microstrip patch antenna at 433 MHz – I have to design a microstrip directional antenna for Man tracking application at 433MHz Please suggest me how can I and which is the best design so that the size of the antenna also must be around 50mm X 50mm at max. Read more
Impedance input and output clarification – I’m confusing the requirements of input and output impedance of any device/circuit. We all know that one of the advantages of MOSFET over FET is the input impedance of MOSFET is high compared to FET and output impedance of MOSFET is less compared to FET. And, regarding the advantage of current mirror circuit, the input impedance of current mirror is less, and the output impedance of current mirror is high. Which one is correct? Read more
HDMI surge protection – I am having an issue in HDMI interface failure due to surge. Currently, I am using ESD protection IC TPD12S016 from TI. But this is for only ESD protection and can not provide surge protection. I also searched for a surge protection chip for HDMI, but I can’t find a proper protector. Read more
Ripple voltage on the battery – I have a balancing circuit as sh
own in the figure. Cells are balancing each other by transporting energy from higher energy cell to lower energy cell. My problem is that; the duty of the capacitors is to smooth battery voltages, but when I change the battery capacities, the ripple voltage changes. I do not know why. Read more
DDS and quality of sinus – Is there a mathematical dependence between the quality of generated sinus, for example, THD, and the number of points generated with a DAC in DDS? And alternatively between DAC resolution and THD? Read more
How do I test this crystal oscillator? – I have a crystal oscillator part no FX135a-327. I was looking into its datasheet for the test circuit, but it does not have.So please help me out with some simple test circuits. I want to calculate frequency stability, Rise time Fall Time, Startup time, etc. Read more
ADC sampling rate question – I have some questions regarding a DAQ system based made by me with FPGA and MAX1285 (12 bit SPI interface): Is the sampling rate dependent with the SPI SCLK?I In the datasheet the max SPI CLK is 4.8 MHz and the max sampling rate is 300 kbps, but I don’t see a relation between them. Read more
