# Tagged Questions

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1k views

### When measuring AC via an ADC, is it bad to have common ground?

I've got a circuit that looks like this: My input is low voltage AC at low current and I want to measure this with an ADC at 3.3V (eventually, haven't got there yet). Is this safe/correct? It ...
138 views

### Voltage/current conversion

I have a device which uses 4.5 watts @ 18V (0.245A). The device can be powered by 12 volts, which I plan to do so. I can I work out the current draw at 12 volts based off the above info?
114 views

### Measuring supply voltage

The documentation for a chip that I'm trying to use says it needs 2.7 to 3.6V. When I use a multimeter and put on probe on Vin and the other on GND I read 1.7V. Is this the correct way to read supply ...
92 views

### Embedded system-current draw logging

I have an embedded application that wakes up every 15 minutes and performs some specific function for a period of two minutes. I need to log the current consumption of this specific function on the ...
538 views

### Measuring Arduino internal voltage reference with respect to Vcc

How do I read the internal reference voltages of the Arduino (Ardino Mega, ATmega2560, specifically the 2.56v reference) with respect to the input voltage? I'm trying to measure the remaining battery ...
274 views

### How can I convert the current from a fan to the microphone headset input on an iphone?

I am working on creating an anemometer (or wind meter) for the iPhone. I am a programmer and know exactly how I could do this on the software side of things, but I am a complete noob when it comes to ...
93 views

### Why do my 3 custom voltage pulses stop working as soon as I plug in the A1362 Hall-Effect sensor?

Why does the Vout pin in the diagram below receive 8 volts with Vcc = 0 volts, but becomes 2 volts when Vcc=5 volts. If switch SW9 is closed, circuit theory says Vout should always stay at 15 volts ...
422 views

### LM317 Ground Problems

I have a LM317 setup as a 3.3V regulator. I am getting 12V input from an Agilent Technologies E3631A Variable DC Power Supply. On this same board I also have a LM7805 regulating to 5V. All of my ...
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### What is the best way to remove the non-rejected portion of a common-mode voltage and any bias voltages from a differential voltage measurement?

I am using a high-common mode differential amplifier (AD629) to measure several DC 10 to 15 voltages stacked together. Since the AD629 is not the cheapest amplifier in the world (though not as ...
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### Need help with generating a bi-phasic current

I'm trying to generate a symmetric biphasic current pulse using a Grass S88 Stimulator. Here's a diagram: SG is a signal generator with two outputs, S1 and S2, which are generating a periodic ...
237 views

### Lipo battery monitor for 1s-6s packs

I want to be able to output lipo battery voltage to a display the remaining juice in the battery much like a fuel gauge. It has to work for 1s to 6s batteries and it would be ideal to work using an ...
1k views

### reading voltage using TI's MSP430 FF22x4

I am trying to measure a power device's voltage using TI's MSP430. The voltage source is connected to A1 (i.e. P4) and ground (i.e. P1) on the target board. Here is the relevant code: ...
482 views

### Balance board with Arduino

We're trying to build a rudimentary Balance Board using four force sensitive resistors and an Arduino unit, but are not sure how to wire up the circuit. How do we connect the sensors to the Arduino?
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### Measuring external voltage on Arduino

I have a Logitech Steering wheel which I would like to interface to an Arduino whilst using it on a Playstation. My aim in the have the inputs from the gas and brake pedals light up a bar graph to ...
248 views

### How can I measure voltages using DrDAQ board without building external sensor?

I just wanted to understand the process of measuring battery...etc. voltages using the DrDAQ device. In their PDF broshure they say: Thanks to the power of your DrDAQ you can also use it as an ...
48 views

I've got a simple circuit powered by one 18650 LIon battery. Now i want to light up a LED when the battery voltage drops under a specified value (e.g. 3,4V) I know it would be easy with a ...
153 views

### Good digital multimeter [closed]

I need a good multimeter which measures volts, amps, resistance, capacitance and inductance. Does anybody know where I can get one? Also, I have one with milliamps, but can only measure up to 200 ...
73 views

### Battery Monitoring IC for 24V 480Ahr SLA

I'm building a battery monitoring system for a large automotive application. Is there any IC tuned to measure a Lead-Acid battery pack's voltage, current and state of charge? The closest I got was ...
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### Wrong voltage sent to output

Using miniLab1008, I am trying to send 10V to my D/A OUT0 but it sends only 5V and when I send 5V, I get 2.5V. I am using the universal library example VOut01.c Is this a board problem? However using ...